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AQUACULTURE HEALTH 

I N T E R N A T I O N A L 

ISSUE 4 FEBRUARY 2006 NZ$10.00

CONTENTS ISSUE 

4, FEBRUARY 2006 

4 

18 

3 EDITORIAL 

Dr Scott Peddie on partnerships between fish farm critics and fish farmers 

4 FOCUS ON SHELLFISH 

Virginia’s Shellfish Pathology Centre 

7 FOCUS ON FINFISH 

New disease identified in Norway’s farmed cod 

8 RESEARCH FOCUS 

Fish immunology under the spotlight in Scotland 

9 CONFERENCES AND MEETINGS 

10 NEWS 

Updates from around the globe 

14 RESEARCH FOCUS 

The power of purified nucleotides 

18 FISH VET CASEBOOK 

Perspectives on koi herpes virus in US ornamentals 


Advancements in fish vaccine development 


Whirling disease research at Yellowstone National Park 


Nocardia seriolae - a chronic problem 

27 COMPANY FOCUS 

Innovative health solutions to global aquaculture 

29 TRAINING AND RESEARCH FOCUS 

Aquatic animal health at the University of Tasmania 

30 

FROM THE COVER 

Schering-Plough Aquaculture 

Aquaculture Centre, 24-26 Gold Street 

Saffron Walden, Essex CB10 1EJ, UK 

Telephone 44 (0) 1799 528167 

Facsimile 44 (0) 1799 525546 

Schering-Plough 

Animal Health Corporation 

PO Box 3182, Union 

New Jersey 07083 1982, USA 

Telephone +1 908 629 3344 

Facsimile +1 908 629 3365 

www. spaquaculture.com 

ISSN 1176-86330 ISSN (web) 1176-8649 

An informative journal for the 

aquaculture health professional 

Published by: 

VIP PUBLICATIONS LTD 

4 Prince Regent Drive 

Half Moon Bay, Auckland 1706 

New Zealand 

Ph +64 9 533 4336, Fax +64 9 533 4337 

Email keith@aquaculturehealth.com 

www.aquaculturehealth.com 

EDITORIAL DIRECTOR: 

Dr Scott Peddie 

PUBLISHER: Keith Ingram 

MANAGER: Vivienne Ingram 

ASSISTANT EDITOR: Mark Barratt-Boyes 

CONTRIBUTORS: 

Julie Alexander, Dr Eugene Burreson, 

Dr Allison Carrington, Dr Duncan Colquhoun 

Ian Carr, Dr Joyce Evans, Dr Erik Johnson 

Dr Phillip Klesius, Silvia Murcia, Jarle Mikalsen 

Dr Barbara Nowak, Dr Anne-Berit Olsen 

Emiliano Rabinovich, Amy Rose 

Dr Mark Sheppard, Dr Craig Shoemaker 

Dr Simon Wadsworth, John Whitehead 

DESIGNER: Rachel Walker 

PRE PRESS/CTP: BPG Digital 

PRINTERS: Business Print Group 

WEBSITE: Web4U 

GENERAL: Reproduction of articles and materials published in Aquaculture Health International in whole or part, is permitted provided the source and author(s) 

are acknowledged. However, all photographic material is copyright and written permission to reproduce in any shape or form is required. Contributions of a nature 

relevant to the aquaculture industry are welcomed and industry participants are especially encouraged to contribute. Articles and information printed in 

Aquaculture Health International do not necessarily reflect the opinions or formal position or the publishers unless otherwise indicated. All material published in 

Aquaculture Health International is done so with all due care as regards to accuracy and factual content, however, the publishers cannot accept 

responsibility for any errors and omissions which may occur. Aquaculture Health International is produced quarterly. 

2 AQUACULTURE HEALTH INTERNATIONAL FEBRUARY 2006

CAN PARTNERSHIPS BE POSITIVE 

Partnerships between fish farm critics and fish farmers - 

do they have positive implications for fish health research 

EDITORIAL 

DR SCOTT PEDDIE, EDITORIAL DIRECTOR 

The recent announcement of closer research cooperation by 

Marine Harvest and the Coastal Alliance for Aquaculture 

Reform in British Columbia, Canada is an interesting one 

from a fish health perspective. 

The debate in west coast Canada surrounding the 

environmental impacts and sustainability of net-pen salmonid 

culture has been highly polarised for some time. The inevitable 

result of this has been what some would view as an unhelpful 

politicisation of scientific enquiry, involving claim and counterclaim 

from the main protagonists. 

The debate centering on the issue of the potential link 

between sea lice infection in farmed salmon and reduced 

performance in wild juvenile pacific salmon has raged on in the 

fish farming press and wider media for several years. Against 

such a backdrop it is difficult to see how any rational progress 

can be made in resolving either perceived or real issues in this 

area. 

Thankfully, both parties have realised this and have jointly 

produced a Framework for Dialogue. Although the framework 

still allows both Marine Harvest and the alliance to publicly state 

their respective cases and respond to issues as and when they 

arise, it provides the basis for a more constructive relationship. 

It should therefore be welcomed as an important step in the 

right direction. 

The issues raised in the document that are up for discussion 

appear at first glance to be very broad indeed, ranging from 

aboriginal rights to technology and socio-economic issues. As I 

read it, the question that immediately popped into my mind 

was, “Does this wide-ranging approach run the risk of 

unravelling for want of a clear focus” 

It seems that this has been mitigated against, at least to some 

degree, by the mutual identification and documentation of 

immediate research priorities as part of the framework. 

It is perhaps not surprising that the focal areas are the 

interaction between wild and farmed salmon and sea lice, 

migration corridors, and the economic 

evaluation of commercial-scale closed 

containment systems. It is a reminder, if 

any were needed, that fish health issues 

are of interest to a wide audience, not 

just readers of this magazine! 

For me, the key point in this document 

is that such research will be undertaken 

on a collaborative basis, reducing the 

likelihood of any bias, intentional or 

unintentional, creeping into the process. 

Nevertheless, as the saying goes, the proof of the pudding is in 

the eating. Given that the results of such research could 

potentially have far-reaching consequences for all parties 

involved, it remains to be seen how it will play out at a practical 

level. 

Notwithstanding the potential pitfalls that could befall such a 

venture as it beds down and evolves, it is certainly worth 

watching. And who knows, maybe it could even become a 

template for conflict resolution in other areas of the world 

where similar heated debates take place 

■ 

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FEBRUARY 2006 AQUACULTURE HEALTH INTERNATIONAL 3

LABORATORY 

THE EXCELLENCE OF VIRGINIA’S 

SHELLFISH PATHOLOGY CENTRE 

BY DR EUGENE BURRESON (SHELLFISH PATHOLOGY LABORATORY, VIRGINIA INSTITUTE OF MARINE SCIENCES, USA) 

The Virginia Institute of Marine Science (VIMS) was 

established in 1940 as an agency to provide scientific advice to 

the state of Virginia as it related to the Chesapeake Bay and 

coastal waters. 

Since its earliest beginnings, VIMS has had a long history of 

research in bivalve mollusc diseases. Early researchers Dr Jay 

Andrews and Dr Frank Perkins provided fundamental 

knowledge on the morphology and biology of the important 

oyster pathogens Perkinsus marinus, Haplosporidium nelsoni and 

Haplosporidium costale. 

Both scientists also worked closely with the Virginia Marine 

Resources Commission, the local management agency, to develop 

methods to assist the oyster industry in managing around the 

diseases. Dr Andrews initiated a disease-monitoring programme in 

1960 that continues to this day, and has provided fundamental 

knowledge on climate impacts on pathogen abundance and 

allowed a predictive capability of annual disease severity. 

Today, the VIMS Shellfish Pathology Laboratory (SPL) maintains 

a broad research programme in parasitology, which encompasses P 

marinus and Haplosporidium species, Bonamia and Marteilia species 

and the clam (Mercenaria mercenaria) parasite QPX. The 

programme is fundamentally directed toward health management in 

molluscan populations in both aquaculture and restoration contexts. 

VIMS has always had an academic affiliation with the College of 

William and Mary; in 1979 the institute was disbanded as a state 

agency and fully merged with the college, while retaining the title 

VIMS SPL STAFF FROM LEFT TO RIGHT: NANCY STOKES, 

DR RYAN CARNEGIE, SUSAN DENNY, KRISTI HILL, DR KIM REECE, RITA CROCKET, 

DR GENE BURRESON (BACK), AND DR CORINNE AUDEMARD 

and advisory mandates of VIMS. The academic programme at 

VIMS is the School of Marine Science of the College of William 

and Mary, and is strictly a graduate programme. 

FACILITIES 

The VIMS SPL, housed within the Department of Environmental 

and Aquatic Animal Health, has a necropsy laboratory, a fully 

equipped histopathology centre with an automated tissue processor 

and slide stainer, and a fully functional molecular laboratory with 

platforms for both standard and real-time PCR as well as DNA 

sequencing. Microscope resources include multi-headed microscopes 

for consultation and teaching, an epifluorescent microscope for 

fluorescent in situ hybridisation, and a high-resolution imaging 

system for image capture and analysis. The VIMS SPL also has access 

to both scanning and transmission electron microscopes and 

running seawater laboratories for experimental work. 

REGIONAL DIAGNOSTIC SERVICES 

Because of the lack of commercial marine finfish or crustacean 

aquaculture in the region, diagnostic services have long focused on 

diseases of oysters (Crassostrea virginica) and hard clams 

(Mercenaria mercenaria). 


VIMS SPL provides diagnostic 

support services and identification 

confirmation to researchers and 

governments worldwide 

The SPL provides diagnostic services to the local oyster and hard 

clam culture industries and to the Virginia Marine Resources 

Commission. Four important protistan pathogens are routinely 

diagnosed. QPX disease in M mercenaria, and H nelsoni and 

Hcostale in C virginica are diagnosed by histopathology; 

Pmarinus in C virginica is diagnosed by Ray’s fluid thioglycollate 

culture medium (RFTM). 

This work is partially subsidised by the state of Virginia. The 

SPL has also been active in developing and applying molecular 

diagnostic tools such as standard and real-time PCR and in situ 

hybridisation, which it applies toward these species as well as 

toward Bonamia parasites (Bonamia ostreae,and two undescribed 

species) that are also present in the region. 

OIE REFERENCE LABORATORY 

In 2000 the VIMS SPL was designated as the sole Office 

International des Epizooties (OIE) reference laboratory for the 

diseases Haplosporidiosis and Perkinsosis of bivalve molluscs. This 

designation recognised the laboratory’s development of molecular 

diagnostic tools for both groups of oyster pathogens. With the new 

OIE focus on specific parasites (eg P marinus) rather than broad 

categories of disease (eg Perkinsosis), the SPL is currently the 

reference laboratory for P marinus, P olseni, H nelsoni and 

Hcostale.The SPL continues nonetheless to take a broader view of 

its role within the international aquatic animal health community, 

and serves as a resource for scientists and health managers 

concerned with Perkinsus species and haplosporidian parasites, 

including Bonamia species, worldwide. 

Four PhD-level scientists are affiliated with the SPL: 

• Eugene Burreson, head of the SPL and professor of marine 

science 

• Kimberly Reece, associate professor of marine science 

(molecular diagnostics of Perkinsus sp, molecular phylogenetics) 

• Ryan Carnegie, assistant research scientist (molecular 

diagnostics of Bonamia sp., molecular phylogenetics), and 

• Corinne Audemard, assistant research scientist (real-time PCR 

of Perkinsus sp). 

In addition, the SPL includes Nancy Stokes (molecular 

diagnostics of haplosporidians), Rita Crockett (histopathological 

diagnoses) and two technical support staff for histopathology and 

molecular biology. 

As an OIE reference laboratory, VIMS SPL provides diagnostic 

support services and identification confirmation to researchers and 

governments worldwide for haplosporidians and Perkinsus sp 

using PCR and in situ hybridisation. The SPL also provides 

reference material in the form of histological slides and positive 

control DNA. 

SURVEILLANCE 

The SPL provides shellfish pathogen surveillance for the state of 

Virginia. The programme includes quarterly oyster sampling along 

a salinity gradient in the James River, an annual fall survey of all 

oyster beds in Virginia, and an annual importation of susceptible 

oysters to monitor for H nelsoni disease pressure. 

Periodic surveillance for the QPX pathogen in M mercenaria 

also occurs at the request of the hard clam culture industry. 

▲ 

SPL STAFF PROCESS 

OYSTERS FOR PERKINSUS 

MARINUS DIAGNOSIS BY 

THE THIOGLYCOLLATE 

CULTURE TECHNIQUE 

DIAGNOSTICIAN RITA CROCKETT 

SHUCKS OYSTERS FOR DISEASE ANALYSES 


LABORATORY 

THE EXCELLENCE OF VIRGINIA’S SHELLFISH PATHOLOGY CENTRE 

THE LOCATION OF THE SHELLFISH PATHOLOGY LABORATORY 

WITHIN THE VIRGINIA INSTITUTE OF MARINE SCIENCE 

THE 

LOCATION 

OF VIMS 

EDUCATIONAL LINKS 

VIMS SPL personnel teach formal courses in the School of Marine 

Science on diseases of marine organisms, systematics and 

phylogenetics, and genomics, as well as other relevant courses in 

conjunction with other VIMS faculties. 

Graduate students are an integral part of the research the 

SPL conducts on shellfish diseases. In addition, as part of our 

OIE Reference Laboratory mandate, VIMS SPL personnel train 

visiting researchers and students from around the world in 

histopathological and molecular diagnostics of shellfish 

pathogens. 

RESEARCH LINKS 

Much of the research conducted by SPL staff is funded by the US 

government and is directed toward developing improved 

diagnostics for known or emerging pathogens, and toward 

increasing our understanding of the biology and pathogenicity of 

disease agents. 

Examples include: 

• documenting through molecular techniques that H nelsoni is 

an introduced pathogen, and working toward resolution of its 

life cycle 

• developing specific PCR and in situ hybridisation assays for two 

new species of Bonamia recently discovered in North Carolina 

• field studies to determine the infection window and seasonal 

cycle of Bonamia sp in North Carolina 

• developing specific DNA probes for Perkinsus marinus, P olseni 

and P chesapeaki 

• the synonymisation of Perkinsus chesapeaki and P andrewsi,and 

• developing real-time PCR for detection of P marinus in water 

samples. 

The SPL has also collaborated in developing P marinus and 

Hnelsoni-tolerant oyster stocks for C virginica aquaculture that 

have been crucial for the growth of this industry, and studies the 

impact of P marinus and H nelsoni on restored populations of 

Cvirginica in Virginian waters. 

The laboratory also works with researchers around the world in 

the identification and molecular characterisation of new and 

emerging parasites of molluscs and crustaceans. 

RELEVANT WEBSITES 

VIMS Virginia Institute of Marine Science - www.vims.edu 

EAAH VIMS Department of Environmental and Aquatic Animal 

Health - www.vims.edu/env 

SPL VIMS Shellfish Pathology Laboratory - 

www.vims.edu/env/research/shellfish/index.html 

Contact details: 

Dr Eugene M Burreson, Department of Environmental and 

Aquatic Animal Health, Virginia Institute of Marine Science, 

PO Box 1346, Gloucester Point, VA 23062 USA 

Phone +1 804 684 7015. fax +1 804 684 7796, 

email gene@vims.edu 

■ 


NEW DISEASE IDENTIFIED 

IN NORWAY’S FARMED COD 

BY DR ANNE-BERIT OLSEN, JARLE MIKALSEN AND DR DUNCAN COLQUHOUN, (NATIONAL VETERINARY INSTITUTE, NORWAY) 

FINFISH 

FIGURE 1: SPLEEN LESIONS IN AN INFECTED FISH 

Apreviously undescribed granulomatous disease in Atlantic 

cod (Gadus morhua L) related to the presence of a Gramnegative, 

facultative intracellular bacterium belonging to 

the genus Francisella has recently been identified in Norway. 

The initial outbreak was identified in a population of mature 

cod weighing 2-4kg held in an enclosed natural seawater “basin” 

on the western coast of Norway. Increased levels of mortality 

were registered in July 2005 at a water temperature of around 

14.5˚C and peaked in August. Accumulated mortality 

reached approximately 40 percent in the five months 

from July to November. Other pathogenic 

agents were not thought to have 

contributed significantly to this total. 

CLINICAL AND 

PATHOLOGICAL 

FINDINGS 

Externally, the fish appeared to have a 

generally emaciated condition. Some 

individuals displayed raised haemorrhagic 

nodules in the skin. All moribund fish 

caught for examination showed extensive 

internal gross lesions, with moderate to massive 

occurrence of white, partly protruding nodules of 

various sizes in the spleen (see Figures 1 and 2), the heart 

(Figure 3), kidney and liver. 

The spleen was enlarged and sero-haemorrhagic ascites and 

thickened intestinal mucosa were observed. Extensive chronic 

granulomatous inflammation with multiple granuloma in all 

organs was the main histopathological finding. Few to 

numerous small Gram-negative bacteria were found 

intracellularly in the granulomas. 

IDENTIFICATION OF ISOLATED BACTERIA 

The bacterium associated with the infection does not grow on 

standard microbiological media, but grows well in cell culture and 

on media with a high cysteine content. A nearly complete 

16S ribosomal RNA sequence was obtained showing a high degree 

FIGURE 3: HEART LESIONS ARE ANOTHER SYMPTOM OF THE CONDITION 

FIGURE 2: SEVERE LESIONS IN 

AN EXCISED SPLEEN 

of homology with 

Francisella spp, including 

isolates previously identified in fish in 

Taiwan (tilapia) and Japan (three-lined grunt). 

Although the present isolate has yet to be fully described, the 

phenotypical evidence so far available comprises compelling 

evidence for its inclusion within the genus Francisella.Ofthe 

limited temperatures tested, the best growth was identified at 22˚C, 

with very weak growth registered at 30˚C and no growth at 37˚C, 

suggesting that the bacterium is probably incapable of surviving 

within a mammalian host. 

OCCURRENCE 

So far three outbreaks have been confirmed by bacterial isolation. 

Histopathological findings consistent with those described above 

have been identified in several other cases currently under 

microbiological investigation. 

■ 


RESEARCH 

FISH IMMUNOLOGY UNDER 

THE SPOTLIGHT IN SCOTLAND 

BY DR ALLISON CARRINGTON (SCOTTISH FISH IMMUNOLOGY RESEARCH CENTRE, UNIVERSITY OF ABERDEEN, UK) 

An ever-increasing consumer demand for fish and shellfish 

products, together with diminishing yields from many 

traditional marine and inland capture fisheries, has 

encouraged a rapid expansion of the aquaculture industry. 

In the past 10 years over 25 percent of the total world supply of 

finfish and shellfish was derived from aquaculture, and with the 

growing pressure to reduce fishing of many marine stocks this 

trend looks set to continue. 

Infectious diseases are a major impediment to the development, 

productivity and profitability of successful commercial fish farms 

that depend heavily on a commitment to animal health. Intensively 

farmed stocks can be significantly affected by infectious diseases 

that occur as intermittent, random events in wild populations. 

The establishment of a comprehensive, cost-effective 

programme of vaccination or prophylactic treatment, negating the 

long-term use of antibiotics and the possibility of microorganisms 

developing resistance to them, is essential in any 

farming environment. 

However, fish are a low-value species and, despite the fact that in 

recent years vaccines have become a major factor in combating fish 

diseases and have made a major contribution to improving fish 

health in aquaculture, cost-effective vaccines for many piscine 

diseases have not yet been produced or approved for use. 

The Scottish Fish Immunology Research Centre (SFIRC) was 

opened in June 2003 with support from the Scottish Higher 

Education Funding Council. The centre combines expertise from 

the University of Aberdeen, the University of Stirling and the FRS 

Marine Laboratory in Aberdeen with the aim of strengthening 

collaborative research in fish health in Scotland and addressing 

fundamental and applied issues relating to fish health. One 

objective of this research is the development of novel effective 

vaccines, immunostimulants/adjuvants, and antiviral/antimicrobial 

reagents for use in farmed fish. We are also developing multiplex 

tests to monitor immune responses in both vaccinated and 

diseased fish. 

IMMUNE SYSTEM 

The fish immune system has evolved a vast array of defence 

mechanisms against invasion by pathogens. However, although 

genetic differences between bony fish and higher vertebrates are 

relatively small, with many of the cellular systems being similar, the 

structure of the fish immune system is different to that of 

mammals. 

Add to this is the fact that there are approximately 24,000 

different species of bony fish (and even more fish species if 

cartilaginous fish are to be included), with considerable 

morphological variation between them, and it is easy to 

understand why the immune processes in fish are poorly 

understood, with relatively few immune cell populations from fish 

having been isolated and characterised. 

To date, immunological studies on fish have concentrated 

principally on species of economic importance such as Atlantic 

salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), 

catfish (Ictalurus punctatus), sea bream (Sparus aurata), sea bass 

(Dicentrarchus labrax) cod (Gadus morhua), common carp 

(Cyprinu carpio) and grass carp (Ctenopharyngodon idellus), 

STATE OF THE ART EQUIPMENT AT THE SCOTTISH FISH IMMUNOLOGY 

RESEARCH CENTRE’S FACS MACHINE 

although this list is growing rapidly. 

One of the aims of the SFIRC is to study the role or roles of 

immune cell subpopulations and to identify and monitor the 

factors that regulate their activation and function. 

AREAS OF EXPERTISE 

Flow cytometry is an excellent method for making rapid 

measurements on cells as they flow, one by one, in a fluid stream 

through a detection point. 

The first commercial flow cytometers were available in the early 

1970s and have since been developed to evaluate a wide range of 

cellular parameters (ie size and granularity) and functions. They 

are mainly used in hospitals or research laboratories to measure 

levels of cell surface and/or internal proteins by labelling these 

proteins with fluorescent dyes. 

Measuring the patterns of expression of these proteins is termed 

phenotyping, and as well as being an essential component of the 

diagnosis of a variety of diseases in humans, analysis of these 

proteins can also provide valuable information about the general 

status of the immune system in both mammals and fish. 

Additionally, many flow cytometers allow single-cell types to be 

identified and separated from the population being studied, 

enabling further specific analysis to be carried out. 

Although we work with a number of fish species, the majority of 

the work carried out at SFIRC is on salmonids. As part of our 

ongoing research into the fish immune system, we are currently 

working to identify fish cell surface proteins that can be used as 

markers for single-cell populations such as cluster of 

differentiation (CD) antigens. 

CD antigens can be present only on a single cell population such 

as CD3, which is present only on T-cells, on more than one cell 

type; CD45, which is present on all leucocytes, or only on cells in a 

particular state of activation; and CD212, which is present on 

activated T-cells and activated natural killer (NK) cells. 

To date more than 262 CD antigens have been identified in 

mammals, and this number is still growing. In contrast, only a 

small number have yet been characterised in fish, and it is not yet 


CONFERENCES AND MEETINGS 

NORTH AMERICA 

Aquaculture America 2006 

Riviera Hotel and Casino, Las Vegas, USA. February 13-16 

See www.was.org/meetings/ConferenceInfo.aspMeetingCode=AA2006 

37th Annual International Association 

for Aquatic Animal Medicine (IAAM) Conference 

Nassau, Bahamas. May 6-10 

See www.iaaam.org/meeting/meeting.html 

10th International Congress of the International 

Society of Developmental and Comparative Biology 

Charleston, South Carolina, USA. July 1-6 

See www.isdci.org/meetings/php 

5th International Symposium 

on Aquatic Animal Health 

San Francisco, California, USA. September 2-6 

See www.fisheries.org/fhs/isaah_2006.htm 

American Veterinary Medical Association 2007 

Convention Aquatic Medicine Programme 

Washington DC, USA. July 14-18, 2007 

See www.fisheries.org/fhs/avma_2007.html 

SOUTH AMERICA 

Aqua Sur 2006 

Puerto Montt, Chile. March 22-25 

See www.aqua-sur.cl 

EUROPE 

Aquaculture Today 2006 

Sheraton Grand Hotel & Spa, Edinburgh, Scotland. March 28-30 

See www.aquaculturetoday.co.uk 

Fish Immunology/Vaccination Workshop 

Wageningen, The Netherlands. April 18-22 

See www.cbi.wur.nl/UK/fish_workshop/ 

OCEANIA 

International Symposium on Veterinary 

Epidemiology and Economics 

Cairns Convention centre, Cairns, Australia. August 6-11 

See www.isveexi.org 

Australasian Aquaculture Conference 2006 

Adelaide Convention Centre, Adelaide, South Australia. 

August 27-30 

See www.australian-aquacultureportal.com/austaqua/aa06.html 

ASIA 

The Second International Symposium 

on Cage Aquaculture in Asia 

The International Conference Centre, Zhejiang University, 

Hanzhou China. July 3-8 

(See item in News this issue) See www.caa2.org 

FORTHCOMING 

known if all the CD antigens present in mammals are found in 

fish, and vice versa, or whether those that are present in fish 

function in the same way as their mammalian counterparts. 

Fluorescently labelled antibodies generated against CD antigens 

can be used in flow cytometry to mark cells of interest, providing 

evidence of which cell types are present in a mixed population and 

their state of activation. 

We are also working to identify and produce antibodies against 

cytokines - small, secreted proteins that act to mediate and regulate 

the activity of cells. They are produced by cells in response to 

immune stimuli such as disease or vaccination, and typically act at 

very low concentrations over short distances and short time spans. 

Cytokines act by binding to specific cell membrane receptors to 

alter the behaviour (gene expression) of the target cell in a number 

of ways, including increasing or decreasing the expression of 

membrane proteins (including CD antigens), cell proliferation and 

secretion of other effector molecules. 

Despite the fact that cytokines are not expressed on the cell 

surface, they can be detected while still inside the cell, again by 

using fluorescently labelled antibodies and flow cytometry, 

allowing their production to be monitored. Up and down 

regulation of specific cytokines following vaccination or disease 

will also be able to be monitored by use of multiplex assays. 

The expression and subsequent actions of a number of 

cytokines is of great interest to immunologists. The production 

of antibodies against fish cytokines, specific cell-surface markers 

and other immune factors will enable us to expand our 

knowledge of the cellular expression of these proteins, helping us 

to elucidate how the fish immune system behaves in both naïve 

and vaccinated or infected fish. Ultimately, this knowledge can be 

used to develop vaccines or other prophylactic treatments for use 

in aquaculture. 

■ 


UNITED STATES: ANIMAL HEALTH 

COMPANY LAUNCHES US WEBSITE 

The Schering-Plough Animal Health Corporation has 

launched a new website, www.aquaflor-usa.com to keep 

the United States aquaculture industry abreast of the 

latest developments with Aquaflor® (florfenicol). The 

company says it is the first antibiotic approved for use on 

US fish farms in more than 20 years. 

The site, produced specifically for the US market, 

includes a newsroom section with educational articles, 

announcements, company news releases and a new series 

of questions and answers. 

Producers can use the web site to access HTML and 

download PDF versions of product literature, as well as a 

handbook on using Veterinary Feed Directive drugs, an 

exclusive status the Food and Drug Administration 

assigned to Aquaflor® and all new in-feed drugs to 

ensure correct usage and long-term effectiveness. VFD 

forms required by the FDA are also available for downloading. 

The scientific articles section features a downloadable PDF file 

of the Aquaflor® Monograph, which summarises all major US 

trials conducted to date to support the product’s use in catfish, as 

well as links to several technical articles presented by scientists at 

industry meetings in recent years. 

An industry links page allows quick access to additional 

information from industry support services and the news media 

serving US aquaculture. 

Aquaflor® Type A Medicated Article is said to be a fast-acting, 

broad-spectrum, highly palatable antibiotic premix developed 

specifically for aquaculture. It has been used worldwide to treat 

highly infectious bacterial diseases in salmon, trout and other 

farm-raised aquatic species. 

It was recently approved in the United States for controlling 

mortality in catfish due to enteric septicaemia associated with 

Edwardsiella ictaluri.Schering-Plough Animal Health says it is 

pursuing additional claims for use in other farm-raised aquatic 

species produced in the United States. 

See www.schering-plough.com 

CANADA: PUBLICATION SHOWCASES 

AQUACULTURE RESEARCH 

Capamara Communications Inc, 

the publishers of the popular 

trade journals Northern 

Aquaculture and Hatchery 

International, has recently 

released the Canadian 

Aquaculture R&D Review 2005. 

Available as a free download on 

the Northern Aquaculture 

website (see www.naqua.com), 

the review contains over 150 

summaries of recent research 

projects on salmon, trout, 

charr, oysters, mussels and 

marine species, plus fulllength 

features on completed 

projects across Canada. 

Several project summaries are 

of interest to fish health 

FRONT COVER OF THE CANADIAN 

AQUACULTURE R&D REVIEW 

professionals, including: 

• Nodavirus research in 

Atlantic cod and haddock 

• the effects of water temperature on cod and haddock health 

• tracing the origin of sea lice infecting wild juvenile salmon 

• disinfecting processing blood water 

• using tidal modelling to 

predict ISA (Infectious 

Salmon Anaemia) dispersal 

• sea lice vaccine research 

• genomics of aquatic animal 

diseases 

• the development of new 

rapid typing methods for 

fish pathogens 

• finding better diagnostic 

tests for IHN (Infectious 

Haematopoietic Necrosis), 

and 

• testing the relationship 

between stress, vaccination 

and Kudoa in Atlantic 

salmon. 

SEA LICE RESEARCH IS A PROMINENT 

FEATURE OF THE CANADIAN R&D SCENE 

EU: DIPNET WEBSITE UPDATES 

Since the last issue of Aquaculture Health International went to 

press, DIPnet (Disease Interactions and Pathogen exchange 

between farmed and wild aquatic animal populations - a European 

network) has updated its website with three new newsletters: 

• Reports on Vertical Transmission of Fish Diseases now Available 

on Web (Newsletter 32). 

• Open Workshop: Review of Evidence for Pathogen Transmission 

and Disease Interactions between Wild and Farmed Shellfish in 

Europe (Newsletter 31). 

• Global Epidemiology: Worldwide Distribution of IPNV is Not 

Only a Consequence of Aquaculture and Commercial 

Movement of Cultured Fish (Newsletter 30). 

• Effects of pathogenic Vibrio tapetis on defence factors of 

susceptible and non-susceptible bivalve species - two recently 

published results (Newsletter 29). 

• A Review of the Norwegian National Action Plan Against 

Salmon Lice on Salmonids: the effect on wild salmonids 

(Newsletter 28). 

• DIPnet Epidemiology Seminar: surveillance of aquatic animal 

diseases (Newsletter 27). 

• Salmon Lice Spread by Currents - but where do they go 

(Newsletter 26). 

See www.dipnet.info/index.htm 

AUSTRALIA: INTERVET ENTERS 

AQUATIC ANIMAL HEALTH MARKET 

Intervet (Australia) Pty Ltd is based in Bendigo, a large town in 

central Victoria, about 200km northwest of Melbourne. The site 

consists of a vaccine manufacturing plant, plus warehousing, 

technical, sales, marketing and administration departments. 

All types of vaccines are manufactured, ranging from live 

freeze-dried vaccines for dogs, cats and poultry to inactivated 

INTERVET AUSTRALIA 


THE 

BARRAMUNDI 

VACCINATION 

TEAM AT WORK 

AT THE DARWIN 

AQUACULTURE 

CENTRE 

cattle, pig and sheep vaccines. The company continues to invest 

heavily in vaccine development, with no fewer than 12 new 

vaccines for five animal species in various stages of development 

and registration. 

Servicing almost exclusively the Australian animal health 

industry, Intervet Australia offers a broad range of vaccines and 

pharmaceuticals, with approximately 40 percent of the business 

being generated from vaccines manufactured in Bendigo. A new 

pilot laboratory was completed in July 2005 to help reduce time 

to market. 

One area of animal health that Intervet Australia had not yet 

explored was that of aquatic animal health (AAH) relating to the 

aquaculture industry. While this sector was obviously growing in 

Australia, its size was previously considered too small. However, 

with government-supported aquaculture production increasing 

rapidly in Australia, and with a need for vaccine solutions to 

finfish diseases, Intervet Australia looked at the possibility of 

making full use of its GMP standards and marrying it to 

Intervet’s existing AAH expertise. Indeed, the Australian 

government recently brought in legislation to ensure that all fish 

vaccines are manufactured according to GMP standards. 

In early 2005, Marine Harvest, which has a large barramundi 

operation in the Northern Territory, sourcing their fingerlings 

from the Darwin Aquaculture Centre, approached Intervet 

Australia to manufacture an autogenous Streptococcus iniae 

vaccine. The vaccine had to be autogenous because Australia’s 

strict quarantine laws do not allow any importation of vaccines or 

vaccine strains without lengthy, rigorous and often expensive 

evaluations. With the help of Intervet Norbio Singapore, the first 

batch was manufactured, and used to successfully vaccinate 

220,000 fish in July 2005. Since then, vaccination has been 

employed as part of Marine Harvest’s health management 

programme. 

Intervet Australia says it has since had several more requests for 

fish vaccines, typically for barramundi and salmon, against a 

variety of bacterial pathogens. 

Although the Australian aquaculture market remains small in 

global terms, it continues to grow with increasing financial support 

from both state and federal governments. The company says it 

plans to become a key player in the industry as it evolves. 

CHILE: CHILEAN MANAGERS STUDY 

NEW TRENDS 

As part of their ‘AquaTrends 2005’ trip in August, a group of fifteen 

Chilean managers in the salmon industry travelled through four 

European countries to learn about the most advanced research and 

production facilities of several European-based suppliers of 

vaccines (Intervet International, The Netherlands), pigments (DSM, 

The Netherlands and Switzerland) and fish feed (EWOS, Norway). 

They also visited Aqua Nor 2005 in Trondheim, Norway, 

where they saw the latest technologies for the sector 

and met international colleagues. AquaTrends 2005 

was the initiative of Intervet Veterinaria Chile Ltda 

(Andres Engelbreit, General Manager and Oscar Parra, 

Product Manager, Aquatic Animal Health) but was 

organised jointly by the three supplier companies. 

The first leg of the trip involved a visit to the Intervet 

International facilities in Boxmeer. The group listened to a 

corporate presentation about Akzo Nobel and heard details 

about the role Intervet played in the veterinary field for 

different animal species, including aquatic animals. 

The group was informed about the latest advances 

to fight important diseases affecting salmon and 

trout production in Chile, including IPN, vibriosis, 

furunculosis and SRS. They also toured the 

Boxmeer site, including seeing “behind the doors” 

of some vaccine production facilities, and became 

acquainted with the procedures Intervet applied 

relating to sterility, biosecurity, automation, good practices 

and quality control in its GLP laboratories and GMP 

production buildings. 

They also met various Intervet staff, including the Boxmeer site 

manager, Jan van Raaij, the director of corporate communications 

and affairs, Dr Sabine Schueller, and scientists in the virology, 

bacteriology, pathology and other laboratories. 

The group then travelled to Switzerland and France to see DSM 

production plants, and to Norway to call into EWOS and 

AquaNor. 

THE AQUATRENDS GROUP DURING THEIR VISIT TO 

INTERVET INTERNATIONAL BV IN BOXMEER 

CHINA: INTERVET SUPPORTS 

MAJOR CONFERENCE 

Cage aquaculture has a long history in Asia, but its potential has 

been far from reached, especially for off-shore cage culture in 

open sea. 

The first cage culture symposium was successfully held more 

than five years ago, and the aquaculture community will meet 

again this year in Hangzhou, China to discuss the recent advances, 

potential, challenges and problems of cage aquaculture in Asia. 

CAA2 will be held from July 3 to 8, and will discuss: 

• recent advances and innovations in cage culture technology 

• cage design, structure and materials 

• site and species selection 

• nutrition, feed, feeding technology and management 

• disease prevention and health management 

• economics and marketing 

• sustainable management and development 

• policy and regulation 

• constraints to cage culture development, and 

• conflicts between cage culture and other stakeholders. 

▲ 


Intervet is an active participant for the symposium. 

Besides being one of the supporting organisations, 

Intervet staff will share their research findings and 

experience in the field of fish health, including a 

presentation on Health management practices for cage 

aquaculture in Asia - a key component for sustainability, 

given by Dr Zilong Tan as one of the keynote speakers. 

Alistair Brown will speak on the success of salmon 

farming with the help of vaccination technology, and 

also serve on the expert panel for an open forum that 

will involve the business sector, farmers, government 

officers, scientists, NGOs and other stakeholders to 

tackle practical issues related to cage culture. 

Intervet will also participate in the international trade 

exhibition held in conjunction with the symposium. 

For further details, including submission of papers 

(deadline March 31), see www.caa2.org 

IRELAND: SEMINAR DISCUSSES PERFORMANCE 

AND PROFITABILITY IN AQUACULTURE 

Alltech hosted a one-day seminar for experts and representatives of 

the major companies and research institutes in the aquaculture 

industry at its European headquarters in Ireland on November 29. 

Over 50 experts from 17 countries attended the meeting. 

The third annual European Aquaculture meeting discussed the 

latest developments of this fast-growing industry. Areas of 

discussion included organic mineral nutrition, gut health status 

and morphology, and new molecular tools to investigate gene 

expression and nutrition. 

The speakers included Professor Giovanni Bernadini, of the 

University of Uninsurbia, Italy, who presented a paper on the use 

of molecular tools to investigate welfare, growth and performance 

in sea bass and other species of commercial interest. He described 

the identification of over 1400 genes in sea bass and, through gene 

expression, related these to stress and environmental conditions. 

Dr Simon Davies of the University of Plymouth in the United 

Kingdom spoke on gastrointestinal morphology in cultured fish 

and the effect of Bio-Mos® on gut integrity: new perspectives. Dr 

Davies explained the role of gut function, prebiotics and mannan 

oligosacharides, which beneficially affect the host by selectively 

stimulating improved gut morphology and function and altering 

microbiota. 

Dr Turid Morkore of the Nutrition Group, Akvaforsk, Norway, 

discussed the dietary impact on fish quality of farmed Atlantic 

salmon. Dr Morkore emphasised the financial importance of the 

flesh colour, fat content and gaping losses. She reported that early 

trial results with Alltech’s Salmon Pak, which includes Bio-Mos® 

and Bioplex®, reduced significantly the gaping losses that are 

responsible for 38 percent of salmon fillet rejection at processing. 

“Alltech has a clear vision on how it can contribute to this 

industry with its products in order to ensure a better performance 

and thus higher profits for the aquaculture industry players,” said 

the European technical manager, John Sweetman. 

Timm Neelsen, the European aquaculture coordinator, added 

that “Products such as Bio-Mos®, Bioplex® and Sel-Plex® have 

shown great results in the diets of aquaculture.” He also explained 

the importance of numerous independent trials. 

NORWAY: PUMPKINSEED (LEPOMIS 

GIBBOSUS) INFECTED WITH NON-NATIVE 

MONOGENEANS 

(Source: Erik Sterud, researcher, National Veterinary Institute, Norway) 

Pumpkinseed (Lepomis gibbosus) heavily infected with gill 

monogeneans were recently found in a pond outside Oslo. The 

monogeneans belonging to the family Ancyrocephalidae are nonnative 

parasites not previously found on fish in Norway. The 

PUMPKINSEED (LEPOMIS GIBBOSUS) 

effects of the introduced fish and 

parasites are unknown. 

Pumpkinseed, a fish native to North 

America, were introduced to European 

waters more than 100 years ago. The 

origin of the fish found in a pond outside 

Oslo is unknown. The gills of the four 

fish examined were heavily infected (50- 

100 parasites) with two ancyrocephalid 

monogeneans. 

ERIK STERUD 

The parasites have tentatively been 

identified as Haplocleidus sp and Onchocleidus sp, both common 

parasites of pumpkinseed. The host specificity and potential effect 

upon native fish species is not known. There is apparently no risk 

of natural dissemination of fish from the pond, but the risk for 

anthropogenic disseminations must be regarded as high. 

The Directorate for Nature Management in Norway will support 

the National Veterinary Institute in a project dealing with parasites 

on introduced fish, where the parasites of pumpkinseed will be 

studied more closely. 

USA: SCHERING-PLOUGH RECEIVES 

APPROVAL FOR AQUAFLOR ® (FLORFENICOL) 

The Animal Health Division of the Schering-Plough Corporation 

has received approval from the US Food and Drug Administration 

to begin marketing Aquaflor® in the United States to control 

mortality in catfish due to enteric septicemia (ESC) associated 

with Edwardsiella ictaluri. 

Schering-Plough claims that Aquaflor® is a highly palatable, 

fast-acting antibiotic proven worldwide to be effective against a 

wide range of bacteria in several aquatic species. It is the first infeed 

antibiotic to be approved for US aquaculture in more than 

20 years. 

Aquaflor®’s sister product, Nuflor® (florfenicol), has been used 

successfully in the United States since 1996 to treat respiratory 

disease in beef and non-lactating dairy cattle. 

After reviewing data on Aquaflor®, the FDA’s Centre for 

Veterinary Medicine concluded that the meat derived from catfish 

that were fed florfenicol was safe for human consumption when 

the fish were fed according to the approved label (CVM Update, 

www.fda.gov/cvm/catfishapp.htm) 

The centre said Aquaflor® was reviewed under its Guidance for 

Industry 152, evaluating the safety of antimicrobial new animal 

drugs with regard to their microbiological effects on bacteria of 

human health concern. 

The agency also determined that Aquaflor® can be used in foodproducing 

animals without creating a public health risk from 

antimicrobial resistance. The product is limited to use by 

veterinarians, a stipulation that will reduce the likelihood of 

resistance developing. 

Unlike sulfa drugs and tetracyclines, Aquaflor® was developed 

specifically for use in food animal species. Schering-Plough claims 

that US studies show that Aquaflor® can be used with no setbacks 

in feed consumption or growth, and that its short, 12-day 


withdrawal period leaves producers with ample marketing 

flexibility. 

“Aquaflor® has proved to be safe and highly effective, with good 

palatability, so we have high hopes for it in the US aquaculture 

industry,” said Dr Patricia Gaunt, associate professor, aquatic 

animal health with the Mississippi State University College of 

Veterinary Medicine. 

In tank trials conducted at the university, catfish fingerlings 

challenged with ESC had a cumulative death rate of only 0.8 

percent, compared with 60 percent for challenged, untreated fish. 

In the same study, treated fingerlings showed an infection rate of 

only 1.7 percent, compared with 72.3 percent for untreated 

controls. 

Palatability trials show that fish consume feed medicated with 

Aquaflor® at the same rate as unmedicated feed - even when 

Aquaflor® was used at 10 times the recommended dose rate. 

Aquaflor® has been used to treat fish species around the world 

since the early 1990s. Its first introduction was in Japan for use in 

yellowtail and other local species, and it was subsequently 

introduced in Europe, Canada and Chile for treating furunculosis 

in salmon. 

Additional approvals have been granted or are anticipated over 

the next several months in Latin American and Far Eastern 

countries for shrimp and species of finfish such as tilapia. 

Additional claims and indications are also being sought in Europe. 

See www.spaquaculture.com and www.aquaflor-usa.com. 

(Aquaflor and NUFLOR are registered trademarks of the 

Schering-Plough Veterinary Corporation) 

MOROCCO: BONAMIA OSTREAE 

OUTBREAK UPDATE 

Details of the final report, submitted to the OIE by the Animal 

Production Department, Ministry of Agriculture and Rural 

Development, Rabat, on the outbreak of Bonamia ostreae in 

farmed flat oysters (Ostrea edulis) in Laayoune Province, can be 

accessed via the Aquatic Animals Commission website. 

See www.oie.int/aac/eng/en_fdc.htm 

PACIFIC ISLANDS: MODEL IMPORT RISK 

ANALYSIS (IRA) FRAMEWORK DEVELOPED 

(Source: Jean-Paul Gaudechoux, Fisheries Information Adviser, 

Secretariat of the Pacific Community, New Caledonia, 

e-mail jeanpaulg@spc.int) 

The Aquaculture Section has engaged a team of international 

consultants to undertake two import risk 

analyses (IRAs) involving the proposed 

introduction of aquatic species. The team, led 

by J Richard Arthur, included Melba Bondad- 

Reantaso, Edward Lovell, David Hurwood and 

Peter Mather. 

The risk analyses were developed to serve as 

models for consideration by other Pacific Island 

countries for future translocations. The IRA 

process can significantly reduce the risks 

associated with translocation that might occur 

from a poorly planned and executed 

introduction or some unanticipated result. This 

is a valuable tool for implementing proper biosecurity 

measures, and constitutes a best 

practice approach for quarantine and 

translocation. 

The IRA process formulated for the Pacific 

has two approaches. Unlike the traditional 

approach, which focuses on pathogenic 

diseases, the model framework for the Pacific 

includes both a pathogen and an ecological risk 

LARVAL MACROBRACHRIUM ROSENBERGII CULTURE AT THE 

MINISTRY OF FISHERIES AND FORESTRY AQUACULTURE CENTRE, 

NADURULOULOU, FIJI 

analysis. The ecological component recognises the high value 

attributed to biodiversity in the Pacific. 

The pathogen risk analysis examines the potential risks due to 

pathogen introduction, along with the movement of the 

commodity, identifies hazards (pathogens) requiring further 

consideration, and recommends ways to reduce the risk of 

introduction to an acceptable level. The analysis was conducted 

using a qualitative approach with six risk categories (high, 

moderate, low, very low, extremely low, negligible). 

The ecological risk analysis focuses on the invasiveness and 

“pest potential” of the species to be translocated, and considers 

the likelihood of its escape and/or release into the natural 

environment, and the nature and extent of any potential ecological 

impacts that could stem from escape or release. To assist in 

assessing the ecological risks, a questionnaire and decision-making 

process was used. 

The first risk analysis concerned the introduction of blue 

shrimp (Litopenaeus stylirostris) from Brunei Darussalam to Fiji. 

See the SPC’s website 

www.spc.int/aquaculture/ site/publications/ documents/ 

Stylirostris_BruneiFiji.pdf 

A second, separate report analysed the risk associated with the 

proposed introduction of giant river prawn (Macrobrachium 

rosenbergii) from Fiji to the Cook Islands. 

See www.spc.int/aquaculture/ site/publications/documents/ 

Macrobrachium Rosenbergii1.pdf 

■ 

PRAWN FARM LOCATED IN NAVUA, 

OUTSIDE OF SUVA, FIJI 


RESEARCH 

THE POWER OF 

PURIFIED NUCLEOTIDES 

BY JOHN WHITEHEAD (WYRESIDE, UK), 

DR SIMON WADSWORTH (EWOS INNOVATION, NORWAY) AND IAN CARR (EWOS LTD, UK) 

The use of a proprietary formula of concentrated and purified 

nucleotides in EWOS boost® for farmed fish results in better 

gut physiology, better fish performance and a better bottom 

line for the fish farmer. This article explores the mechanism 

behind this revolution in bioscience. 

Through a focused research programme, EWOS has recognised 

the unique “power” of nucleotides to form an integral part of their 

dietary strategies for farmed salmon and other aquaculture species. 

FIGURE 1: EFFICACY. EWOS BOOST ® HAS BEEN REPEATEDLY SHOWN TO 

IMPROVE GROWTH RATES THROUGH IMPROVING GUT PHYSIOLOGY IN 

FARMED FISH. (TRIPLICATE TANKS, 100 ATLANTIC SALMON SALMO SALAR 

SAMPLED PER TANK, P

RESEARCH 

THE POWER OF PURIFIED NUCLEOTIDES 

FIGURE 3. SUPPLEMENTATION. ORAL SUPPLEMENTATION OF THE RIGHT BALANCE OF 

ALL KEY NUCLEOTIDES IN A PURIFIED FORM REDUCES THE TIME AND ENERGY REQUIRED 

FOR BUILDING DNA AND CELL PROLIFERATION IN THE BODY, PARTICULARLY DURING 

PERIODS OF ELEVATED DEMAND. 

• improve production and reproduction 

• increase growth and survivability 

• reduce parasite infestation 

• improve feed conversion 

• accelerate immune response, and 

• reduce mortality rates 

giving “healthier fish and a healthier bottom line”. 

AQUACULTURE-SPECIFIC 

NUCLEOTIDES 

Fundamental research into the role of the different 

nucleotides and their specific effect on 

overcoming stress and challenges in aquatic 

animals resulted in the design of “aquaculturespecific” 

combinations of nucleotides forming the 

basis of EWOS boost®. 

Repeated trials in many aquaculture species have 

clearly demonstrated that dietary nucleotide 

products are proven only to be efficacious if they 

contain exact, highly concentrated and 

differentiated formula of nucleotides. If not, 

substantial efficacy is not always obtained or 

obtainable (see Figure 3). Therefore, the 

assumption that any good diet or aqua supplement 

claiming merely “to contain nucleotides” is 

similarly efficacious, or even beneficial, is 

certainly incorrect. 

most readily absorbed through the intestinal wall. 

Furthermore, the Swiss found that an abundant and readily 

available natural nutrient was the perfect resource to obtain and 

process the entire spectrum of purified nucleotides and 

nucleosides. Additional research focused on varied physiological 

differentiations among species which require discrete nucleotides 

leading to unique nucleotide formulas for fish, and EWOS boost® 

became a reality. 

These discoveries, along with the increasing scientific research 

into the use of nucleotides in all animal species and humans, led to 

the international debut of the EWOS boost® feed programme for 

salmon. This programme utilised the benefits of a specific 

aquaculture nucleotide blend to form the core of the EWOS 

programme targeting “health through nutrition”. 

This has subsequently led to the further development and 

launch of other EWOS’ special dietary formulations for a variety of 

life-stages and different aquaculture species. Across the spectrum 

of fish culture, nucleotide biotechnology has allowed EWOS to 

help fish farmers 

• control disease more effectively 

• lessen the negative effects of stress 

FIGURE 4: CELL DIVISION. THE MULTIPLICATION OF CELLS REQUIRES THE 

DOUBLING OF INFORMATION STORED IN THE FORM OF DNA. OVER THREE 

BILLION NUCLEOTIDES (ALL FORMS) ARE REQUIRED FOR EACH CELL. TIME 

AND ENERGY ARE REQUIRED TO SYNTHESIS EACH NUCLEOTIDE, INVOLVING 

UP TO 14 BIOCHEMICAL STEPS. 

THE MECHANISM FOR NUCLEOTIDES 

Cell proliferation describes the reproduction or multiplication of 

all living cells. This process, by which cells divide, is imperative to 

life of all organisms and is fundamental to their biological 

functions. For just a single cell to divide, it is necessary for its DNA 

to be duplicated. Amazingly, every strand of DNA contains 

approximately three billion nucleotides! 

When considering the fact that most fish must produce 

millions of new cells every second simply to maintain the status 

quo, it is quite easy to understand that during times of 

extraordinary stress, such as growth, reproduction, 

environmental change or challenge, combating disease and 

recovery from injury, trillions of additional nucleotides must be 

readily available for cell proliferation. However, since the 

organism must first produce these nucleotides, this continual 

process is slow and metabolically taxing (see Figure 4). 

Most cells are capable of producing sufficient nucleotides to 

maintain a satisfactory supply to the organism for normal 

metabolic activities and life. For a healthy fish, this constant resupply 

of nucleotides is very well balanced and is appropriately 

adjusted in response to occasional stress. However, an increased 

production of nucleotides takes time and energy, and taxes the 

fish’s supply of basic raw materials to produce more nucleotides. 

The fish’s own production of nucleotides is based on average 

requirements, with allowances only for occasional short-term 

increase in response to growth, health challenge etc. 

For a fish to maintain good health, much depends on how 

quickly it can adapt to changing conditions. It does this by 

increasing the defence cells specific to an invading organism or 

disease. However, only very few defence cells recognise these viral 

invaders or errant conditions and move to destroy them. 

But the speed by which the body is able to produce new defence 

cells depends essentially on the availability of the right 

nucleotides. If the body has to first produce the specific 

nucleotides, valuable time is lost during which the disease 

condition progresses or the invader can multiply unhindered. 

However, if enough differentiated nucleotides are available, the 

production of the defence cells begins immediately, allowing the 


Success with EWOS boost ® became a catalyst to explore 

scientifically the potential benefits of nucleotide supplements in 

aquatic diets for other species 

body to begin the fight against the infection or errant condition 

during its initial stages. 

Dietary nucleic acids, from which the body’s source of dietary 

nucleotides is obtained, are found in ingredients of both plant and 

animal origin. However, these nucleotides are at quite a low 

concentration, especially in plant-based proteins. Also, their inherent 

protective proteins further limit their availability to the organism. 

Therefore, the ingestion of additional selected pure nucleotides will 

ensure a much greater and readily available supply of these cellbuilding 

blocks needed by the body during times of elevated demand. 

EWOS’ research scientists used this knowledge in the formulation 

and development of EWOS boost® and supporting programmes 

targeting better health through nutrition. This knowledge also 

continues to be the foundation of EWOS’ continuing research and 

development into providing optimum nutritional value in their 

current and future aquaculture feed programmes. 

NATURAL IMMUNITY 

The underlying reason for the success of purified nucleotidesupplemented 

aquaculture diets, and for the wide range of desirable, 

observable and measurable effects they have, lies in the fact that the 

added nucleotides facilitate an accelerated immune response. 

An immune response is simply the ability of an organism to 

mount an effective defence against malignancies and invading 

micro-organisms (antigens) by producing immunoglobulins 

(antibodies). In general, the immune response is activated through 

the production of millions of specialised white blood cells 

(B-lymphocytes or B cells, plasma cells, and T-lymphocytes or 

Tcells). Since this cell proliferation depends on the ready 

availability of nucleotides, it becomes clear why the immune 

response is accelerated when more nucleotides are made available. 

A strong immune system is equally important for fish in their ability 

to respond to other stress factors, such as injury, sudden environmental 

changes, physical exertion and growth, to name a few. Such pressures 

tax the immune system and, consequently, the ability to survive and 

adequately react to traumatic changes during its lifetime. 

EWOS BOOST ® - DRIVEN BY RESULTS 

In other common aquaculture species such as shrimp, nucleotide 

programmes have demonstrated a highly significant effect on 

health and performance parameters of interest to commercial 

producers. Its perceptive scientists measured the value of 

nucleotide supplements by incorporating an exclusive nucleotide 

formula into high quality and cost-effective diets for salmon for 

various cycles during their development. 

The results of these trials were dramatic. When comparing 

various groups of fish fed standard versus nucleotidesupplemented 

feed, the nucleotide diets, administered anywhere 

from three to 10 weeks, showed a number of significant 

zootechnical advantages, including: 

• “a remarkable 21 percent” increase in length of intestinal villi, as 

well as increased surface area, as shown in micrographs 

• an 11.8 percent to 12.1 percent increase in fry growth rate after 

three weeks of nucleotide feed, and 25.53 percent after six weeks 

• 9.2 percent increase in mean weight of fish fed for eight weeks 

(14.7 percent higher with added vitamin C) 

• 38 percent reduction in sea lice infestation 

• 18 percent decrease in mortality in fish infected with Vibrio 

anguillarum, and a 

• 95 percent survival rate (versus 79-84 percent) after vaccination 

and challenge with Aeromonas salmonicida. 

As a result, EWOS developed and marketed its unique EWOS 

boost® diet and now has a leading world market share among 

competing formulas, with sales of EWOS boost® fast approaching 

10 percent of the company’s worldwide yearly feed sales. 

In other aquaculture species such as shrimp, nucleotide 

programmes have also demonstrated a highly significant effect on 

health and performance such parameters of concern and interest 

to commercial producers. Trials in Asia, India and South America 

have shown a significant reduction in the effects of stress, reduced 

mortality, higher growth and feed efficiency. 

EWOS BOOST ® - 

HARNESSING THE POWER OF NUCLEOTIDES 

Success with EWOS boost® became a catalyst to explore 

scientifically the potential benefits of nucleotide supplements in 

aquatic diets for other species. As a result of other research and 

development programmes, EWOS has expanded the use of its 

product into other phases of salmon development, and unique 

dietary programmes for hatcheries and diets for cod, halibut, 

turbot, sea bass, sea bream, yellow tail, tuna and amberjack. 

EWOS boost® has also gained approval for certain organic 

accreditation, allowing it to be used in the process of rearing fish 

in organic systems, where access to medication is strictly limited. 

Over the last two years, significant investment has been made in 

developing a routine analytical process that accurately determines 

the level and quality of the individual nucleotides present in 

EWOS boost®. This process ensures consistency in the quality of 

the nucleotide formulas used. 

The use of dietary nucleotides to positively effect growth, 

survivability, disease challenges, stress resistance and other factors 

in fish and animal farming is continually expanding. EWOS has 

played a most important and instrumental role in making this 

happen through its significant commitment to an ongoing 

scientific research programme at EWOS Innovation in Norway, 

and its continuous quest to develop and manufacture the very best 

dietary programmes for aquaculture. 

See www.ewos.com or contact per.sveidqvist@ewos.com 

FURTHER READING 

The Journal of Nutrition, January 1994 Supplement; Nucleotides 

and Nutrition, Volume 124, Number 1S 

■ 

VIP.AC04 


C ASEBOOK 

PERSPECTIVES ON KOI HERPES 

VIRUS IN US ORNAMENTALS 

BY DR ERIK JOHNSON (JOHNSON VET SERVICES, GEORGIA, USA) 

TAKING A BLOOD SAMPLE 

FROM AN ANAESTHETISED KOI 

Iam a veterinarian in Georgia with a specialty in fish health. Over 

the years, my caseload has refined itself to one principally 

composed of pond fish of economic or sentimental importance. 

I do not treat food fish, nor do I know much about them. I have 

become very aware of the problems facing the ornamental 

hobbyist and their suppliers, but I am grateful that those of us 

treating pet fish are not hamstrung by some of the limitations 

facing the food fish industry. 

I’m sure that the food fish veterinarian is sometimes jealous of 

the liberty we have in terms of medications for our ornamental 

patients. But still there must surely be jealousy the other direction, 

in that for the food fish practitioner, it’s “okay” to lose a few fish, 

because few specimens of trout or salmon are formally named, and 

sacrifices for a diagnosis can be easily made. 

In the private practice of ornamental fish health, sometimes the 

fish you want to sacrifice for a diagnosis is “the” fish they 

specifically want you to save. So there are advantages and 

disadvantages of practicing either food fish medicine or 

ornamental fish medicine. There are trade offs. 

Since I do not practice food fish medicine, I wanted to write a 

document that informed and entertained on specific issues 

developing in my area of experience. I will therefore mention some 

pertinent issues to let you know what’s going on in that “other 

world” of fish health. 

I want to discuss koi herpes virus (hereafter referred to as KHV) 

in the first of this series of articles. I hope you find my 

interpretations and thoughts enlightening, informative and helpful. 

HISTORY OF KHV 

KHV was first described as early as 1996 in Japan. Researchers 

identified it as a Corona virus and it was a serious but narrowly 

experienced event, killing a lot of a few fish groups, and then 

seemingly disappearing. It showed up again in a group of Japanese 

fish being held in England. 

The fish were being moved en masse to Israel, because it was 

unknown whether some as yet undetected intoxication or water 

quality issue was causing their rather rapid demise. 

The fish went to Israel, where they contaminated (and killed) a 

formidable amount of fish on a koi farming kibbutz. Israeli 

researchers were forthright and published mightily on the virus, 

A KOI INFECTED WITH KHV 

and the preponderance of information we have on the koi herpes 

virus comes from the original work done in Israel - and so the 

virus is erroneously referred to as an Israeli phenomenon. 

WHAT IS IT 

KHV is a herpes virus that features very high morbidity and nearly 

100 percent mortality. The virus is spread to vulnerable fish under 

stress, usually cohabited in confined facilities. Crowding and comorbidity 

with Costa or other pathogens seems to increase its 

virulence. The KHV virus has certain temperature-related 

“windows” of opportunity or action that have been instrumental 

in its occurrence and control. 

I have been professionally involved in countless cases in North 

America, and most of them feature the same sorts of hallmarks: 

• introducing and mixing of new fish without quarantine 

• fish have come from cold water, usually under 70˚F, and 

• fish have been transported and have Costia co-morbidity. 

Most fish are of Asian origin. However, I have seen few cases 

from Japan. From personal experience it seems that the incidence 

in Taiwan, Malaysia and China is ten-fold higher. 

Many cases were confounded as far as their recognition, 

because the fish came from spring-fed, cool ponds and were only 


A KOI POND WATER HEATER. THERE IS SOME EVIDENCE THAT TEMPERATURE 

MANIPULATION MAY BE AN IMPORTANT MEANS OF CONTROLLING KHV 

warm while they were in 

quarantine or during 

transport. When fish “break” 

with clinical KHV infections, but 

are placed in cool water again, their 

symptoms can subside and the rate of 

their decline and death can become 

deceptively slow. Recognising the hallmarks 

of KHV infection can help identify the disease, regardless of the 

rate of their demise. 

CLINICAL SIGNS 

The main clinical signs of KHV are: 

• fish skin begins to peel, especially at the nape of the head 

• fish become reddened and appear abraded overall 

• gills are damaged by the removal of the epithelial cells, 

secondary infections rapidly set in and gills summarily necrose 

• lack of oxygen causes the fish to become fearless and unaware 

• internal organs may liquefy, and an unusually copious amount 

of fibrin can be found in these peritoneal cavities, and 

• the kidney is damaged, but fish often die before that effect is 

grossly observable. 

DIAGNOSTIC TESTS 

The proper diagnosis of KHV is via any of three diagnostic tests. 

The PCR (polymerase chain reaction) test uses an enzyme-linked 

immunosorbent assay and detects crucial segments of specifically 

identifiable DNA from the virus. 

Another test can actually detect circulating antibodies via 

agglutination and is wonderful for finding out whether a fish has 

recently been infected or not. 

The third test is called in situ hybridisation, and it uses enzyme 

markers to find and illuminate viral DNA or particles in fixed 

tissues. This last test doesn’t just prove the presence of the virus as 

the PCR test does. The in situ hybridisation test proves actual 

infection because it demonstrates the virus inside the cell. 

The importance of the tests: 

PCR testing reliably shows the presence or absence of the virus on 

tested samples. It does not prove infection, and the absence of virus 

particles doesn’t conclusively prove a lack of infection. The presence 

of the virus at detectable levels varies as the infection progresses. 

Agglutination testing holds promise on very expensive koi as a 

pre-purchase examination; to wit, before the purchase of a valuable 

fish, the buyer should require an agglutination (antibody) test be 

run to ensure they are buying non-exposed/non-infected specimens. 

If no antibodies are found in a mature fish in good clinical 

condition, it is assumed (with all that that implies) that the fish is 

not infected and has not recently been infected, as antibodies can 

circulate for up to a year after infection. 

Finally, in situ hybridisation is a way of looking at various tissues 

to see where and if the virus “hides” in neural, meningeal, brain or 

other tissues latently. It also proves for research purposes that a fish 

that you’re bleeding for agglutination testing and antibody studies 

was in fact infected when that has been experimentally attempted. 

It’s the only and best “proof” that the fish actually contracted the 

disease and can therefore contribute meaningfully to 

latency and sustainable antibody studies. 

Vaccine research is underway at several 

universities, heavily funded by scant hobbyist 

donations and industry participation. Very little 

support for KHV research has come from the 

actual breeders and vendors of koi. The majority 

of funding has come from hobbyists, and companies that 

supply dry goods such as food to the industry. The 

amounts raised are disappointing, and the funds are 

being distributed to many different organisations for 

various studies. 

The result will be that the research needed to 

characterise the virus and develop immunisation 

protocols, technologies and resources will be splintered 

among many different research facilities, which will end up 

with many entities having all the pieces, but no one entity 

being able to bring them to bear on the virus and its eradication. 

Until then, control of the virus and its effects to save fish lives and 

restore collections of fish have been developed. 

WATER TEMPERATURE MANIPULATION 

Because of the above industry-funding allocation snafus, I wanted 

to contribute some thoughts and experiences on the “control” of 

KHV. The virus is easily quelled by heating infected fish to 83- 

86˚F. I have found that heating infected fish at a rate of one degree 

Fahrenheit per hour is fast enough and slow enough to permit 

control of the viral symptoms without killing the fish via toorapid 

warming. 

As I often say, aeration while heating is supposed to be absurdly 

aggressive, short of creating a Jacuzzi effect that tosses the fish out. 

Within a short time of achieving temperatures in the low eighties 

Fahrenheit, fish begin to exhibit more normal body comportation, 

and success rates have been nothing short of amazing. Survivors by 

heat treatment have not been infective for years after their recovery. 

However, careful examination of tissue samples and various 

agglutination tests are only underway, and not yet available. 

I am presently waiting for the University of Georgia to start and 

conclude studies on my behalf, and funded by me to grow KHV in 

carp fin cell lines and then demonstrate the virus particles in the 

media. Then, in a highly oxygenated environment, I want the cultures 

to be heated gradually (one degree per hour) to 83˚F, and a second 

tray to 86˚F. Then I want these cultures to be examined via electron 

microscopy again to show the condition of the virus in the cells. 

This study would conclude two things: 

1. In the absence of the koi immune system in the cell lines, it 

could no longer be argued that the koi immune system accounts 

for the beneficial effects of heating the virally infected fish to 

86˚F. 

2. We may be able to show that the virus (being heat labile) is 

denatured/coagulated at those temperatures. The results would 

create a high confidence interval that heating koi is an effective 

way of ridding the fish of the virus, and so heating could 

become the accepted and traditional “cure” for KHV without the 

half-million dollar investment in vaccine research. 

We could use the money that is saved for a trip to Cabo San 

Lucas Mexico for all concerned parties and margaritas for a 

month. Or, seriously, we could put the money saved into better 

drugs to control other important diseases such as Costae. Perhaps 

a tame toluidine stain or a perfect dosing regimen for Acriflavine 

I thank you for your attention. I look forward to contributing to 

this journal more often. To do that most propitiously, it would be 

great if you wrote to the publisher and editor with your thoughts 

on what I could bring you from the microcosmic world of 

ornamental fish medicine. 

See www.koivet.com 

■ 


FINFISH 

A US PERSPECTIVE 

ON ADVANCEMENTS IN 

FISH VACCINE DEVELOPMENT 

BY DR PHILLIP KLESIUS, DR JOYCE EVANS AND DR CRAIG SHOEMAKER 

(UNITED STATES DEPARTMENT OF AGRICULTURE, AGRICULTURE RESEARCH SERVICE, AQUATIC ANIMAL HEALTH 

RESEARCH LABORATORY, AL AND CHESTERTOWN, MD) 

During the past decade, 

aquaculture production has 

significantly increased in 

many parts of the world. Seafood 

provides 16 percent of the animal 

protein consumed by humans. 

From 1992 to 2001, the United 

Nations’ Food and Agriculture 

Organisation (FAO) reported that 

total seafood supply increased by 

29.8 percent, whereas the supply of 

wild-captured fish increased by 

only 8.3 percent. The FAO also 

reported that global aquaculture is 

increasing by 11 percent per year 

and is the world’s fastest growing 

food-producing sector. More recent 

FAO figures have also confirmed this trend. 

The incidence and emergence of new infectious diseases has 

almost paralleled the growth of the aquaculture industry. The 

increasing impact of infectious diseases on production is likely to be 

the result of sub-optimal production husbandry practices, intensive 

culture at high fish densities, the lack of health management 

practices and the introduction of sick fish to healthy populations. 

The movement of fish, eggs and genetic material from country 

to country has resulted in the introduction of new diseases for 

which the fish have little or no resistance. The overall economic 

impact of fish diseases is difficult to determine, but may be as high 

as 10 to 15 percent of the total value of fish production worldwide. 

Certain diseases may destroy the entire production chain, and 

often result in the destruction of healthy fish in the affected area in 

an effort to control the epizootic from spreading to other regions 

or countries. 

The aquaculture industry has made remarkable biotechnological 

advancements in the past five years. These advancements in areas such 

as fish vaccines are necessary to meet the rapid growth of the 

aquaculture industry worldwide. The use of vaccines for humans, food 

animals and pets to prevent disease is a common practice. Similar 

biotechnological advancements in the development of efficacious fish 

vaccines for disease prevention in cultured fish are on the rise. 

From 1976 to the present, the number of commercially available, 

safe and efficacious fish vaccines has increased from one to more than 

14. The majority of these vaccines are to prevent bacterial diseases. 

However, several vaccines are also available to prevent viral diseases. 

The majority of the available bacterial vaccines are of the killed 

type (i.e. the infectious agent(s) are inactivated or killed). Killed 

vaccines are primarily administered by injection and are therefore 

costly because of the need to handle and inject each fish. 

KILLED STREPTOCOCCAL VACCINES 

Streptococcus iniae and Streptococcus agalactiae are major pathogens 

that cause serious economic losses in tilapia and numerous species 

IMMUNOFLUORESCENT ANTIBODY STAINED EDWARDSIELLA ICTALURI 

(RED) AND FLAVOBACTERIUM COLUMNARE (GREEN). 

(Courtesy of Dr Victor Panagala, USDA, ARS, 

Aquatic Animal Health Research Laboratory) 

of freshwater, marine and estuarine 

fish worldwide. 

Efficacious S iniae (US Patent 

6,379,677 B1) and S agalactiae 

(patent pending) vaccines were 

developed and patented by the 

Agricultural Research Service, 

Aquatic Animal Health Research 

Laboratory at Auburn, AL and 

Chestertown, MD using 

formalin-killed cells and 

concentrated extra-cellular 

products. 

A specific antibody response 

appears to confer protection for 

both the S iniae and S agalactiae 

vaccines. The finding that extracellular 

products of these Gram-positive streptococci are 

important immunogens that confer protective immunity 

following immunisation is a notable advancement in the 

development of efficacious killed vaccines. Indeed, commercial 

vaccines are now on the market. 

ATTENUATED VACCINES 

The development of attenuated bacterial vaccines was a 

biotechnological breakthrough. Attenuated vaccines are made by 

changing virulent pathogens so they retain the ability to infect and 

cause the host to mount an effective immune response without 

causing mortality, adverse reactions or reverting to the virulent form. 

Attenuated vaccines can be successfully administered by bath 

immersion, a cost-effective method of mass immunisation of large 

numbers of fish. Equally important, attenuated vaccines can be 

successfully used to immunise fingerlings and fry as young as 

seven to 10 days after hatching. This immunisation will last the life 

of their production cycle, as opposed to a shorter duration of 

about six months for a killed vaccine. 

Examples of the first US-licensed attenuated bacterial vaccines 

are those against enteric septicemia of catfish (ESC) and 

columnaris disease of catfish. These attenuated vaccines were 

developed and patented by the Agricultural Research Service, 

USDA, Aquatic Animal Health Research Laboratory at Auburn, AL 

(US patents 6,019,981 and 6,881,412). Edwardsiella ictaluri,the 

causative agent of ESC, costs the catfish industry about US$50-60 

million annually. 

Columnaris disease caused by the bacterium Flavobacterium 

columnare, costs the catfish industry about $40 million annually. 

Both diseases are generally found together, compounding these 

industry losses. The Agricultural Research Service, USDA, licensed 

both vaccines to Intervet, Inc, Millsboro, DE which 

commercialised the vaccines. 

The ESC and columnaris vaccines are commercially labeled 

Aquavac-ESC® and Aquavac-COL®, respectively. The economic 


ESC IMMUNISED CHANNEL CATFISH 

(ARS photo news story, Agricultural Research, May 2005) 

impact of the ESC vaccine is an increase of producer profit by 

$1706 per acre and a significant reduction in loss due to disease. 

The results show that both vaccines significantly increased the 

survival of the immunised channel catfish. 

DNA VACCINES 

Deoxyribonucleic acid (DNA) vaccination is another example of a 

biotechnological advancement to protect fish from pathogens. The 

basis of a DNA vaccine is the delivery of a gene encoding for a 

protective vaccine antigen. The vaccine gene is expressed by the host 

muscle cells to produce the vaccine antigen, which in turn stimulates 

the host immune system to provide protection against the pathogen. 

Intramuscular injection of DNA vaccines against the major viral 

diseases of salmon, such as infectious hematopoietic necrosis virus 

(IHNV) and viral hemorrhagic septicemia virus (VHSV) has 

resulted in protection in laboratory trials. Moreover, a commercial 

variant of the former was approved by the CFIA in Canada last year. 

IN OVO AND ORAL VACCINATION 

Different methods of administration for mass vaccination can be 

employed to maximise the protection conferred by different 

vaccine types. In ovo immunisation of channel catfish eggs 

(US patent 6,153,202) with attenuated ESC vaccine resulted in 

protection against ESC in fingerlings. 

This is the earliest life stage at which fish have been successfully 

immunised with an attenuated vaccine. The commercial use of 

in ovo immunisation would allow for a very cost-effective method 

of mass vaccinating fish. 

Oral immunisation is also a recent biotechnological 

advancement. Vaccines must be delivered on a mass scale to be 

effective, thus oral vaccination, like in ovo vaccination, is appealing. 

The basis of oral vaccination is to protect the vaccine components 

from destruction by the fish digestive tract so that the antigens are able 

to penetrate the intestinal lining and stimulate an immune response. 

PerOs Technologies, Inc, of St Nicolas, Canada, has developed its 

patented Oralject TM technology that prevents the degradation of 

the vaccine’s components by digestive enzymatic function and 

decreases the gastric pH of the fish intestine. 

Currently, the ARS patented Streptococcus iniae vaccine 

(US patent 6,379,677 B1) was incorporated into Oralject TM and fed 

to tilapia. The S iniae Oralject TM vaccine was efficacious following 

challenge with live S iniae in the oral-immunised tilapia. 

VACCINATION AS PART OF THE AQUATIC 

ANIMAL HEALTH MANAGEMENT PLAN 

The practice of culturing finfish is dependent on the 

employment of health management and biosecurity 

measures in which vaccination is an integral tool for 

the producer. Thus, vaccines are a management tool in 

aquatic animal health management and biosecurity plans 

to prevent disease outbreaks and the introduction of 

economically devastating pathogens into the producer 

facilities. 

Increased global trade of aquaculture products depends on 

the continued advancement of these and other such 

biotechnical contributions. 

ACKNOWLEDGEMENTS 

The authors wish to acknowledge Laura McGinnis and 

Lisa Biggar for their helpful editorial assistance. The use of a trade 

or manufacturer’s name does not imply endorsement by the 

US Department of Agriculture. 


Hill B 2005. The need for effective disease control in international 

aquaculture. In: Midtlyng P (ed) Progress in Fish Vaccinology. 3rd 

International Symposium on Fish Vaccinology. CAB Press, Basel, 

Switzerland. pp 3-12 

Horne M 1997. Technical aspects of the administration of vaccines. 

In: Gudding R, Lillebaug A, Midtlyng P, Brown F (eds) Fish 

Vaccinology. Developments in Biological Standardisation. Vol 90. 

Karger, Basel, Switzerland. pp 79-89 

Klesius P, Evans J and Shoemaker C 2004. Warm water fish 

vaccinology in catfish production. Animal Health Research 

Reviews 5. pp 305-311 

Klesius P, Evans J, Shoemaker C and Pasnik D (in press). 

Streptococcal vaccinology in tilapia aquaculture. In: Lim C, 

Webster C (eds) Tilapia: Biology, Culture and Nutrition. Haworth 

Press, Binghamton, NY. 

Lorenzen N and LaPatra S 2005. DNA vaccines for aquacultured 

fish. Scientific and Technical Review International Office of 

Epizootics 24. pp 201-213 

Vandenberg G 2004. Oral vaccination for finfish: academic 

theory or commercial reality Animal Health Research Reviews 5. 

pp 301-304 

■ 


FINFISH 

WHIRLING DISEASE RESEARCH 

AT YELLOWSTONE NATIONAL PARK 

BY AMY ROSE (FORMERLY OF THE WHIRLING DISEASE INITIATIVE, USA), 

SILVIA MURCIA AND JULIE ALEXANDER (MONTANA STATE UNIVERSITY, USA) 

CAGES WERE PLACED IN 

PELICAN CREEK TO TEST 

SENTINEL FISH FOR EXPOSURE 

TO M CEREBRALIS 

STREAM FLOW WAS AMONG THE HABITAT CHARACTERISTICS 

MEASURED IN YELLOWSTONE LAKE TRIBUTARIES 

The Whirling Disease Initiative was established in the USA by an 

Act of Congress in 1997. Its purpose is to conduct research that 

develops practical management solutions to maintain viable, 

self-sustaining wild trout fisheries in the presence of the whirling 

disease parasite. 

The initiative’s ultimate clients are state, tribal and federal fisheries 

management agencies and the constituencies they serve. 

Yellowstone National Park, located in the western United States, is 

the stronghold for the native Yellowstone cutthroat trout 

(Oncorhynchus clarki bouvieri),a species that is increasingly rare 

outside of the park. The adfluvial population of Yellowstone 

cutthroat trout associated with Yellowstone Lake is the largest inland 

population in the world (Koel et al, 2005). Yet even within the park, 

this population of trout is challenged by several factors. 

Whirling disease, caused by the myxozoan parasite Myxobolus 

cerebralis, is one of three major factors contributing to recent trout 

population declines in Yellowstone Lake and its spawning 

tributaries. The other factors, predation by non-native lake trout 

(Salvelinus naymaycush) and years of drought, play a significant role 

and are addressed elsewhere. In this article, we address the ongoing 

problem of whirling disease, and the research strategies designed to 

assist in managing Yellowstone cutthroat trout within Yellowstone 

National Park. 

PART 1: FROM DISCOVERY 

TO LARGE-SCALE INVESTIGATIONS 

Myxobolus cerebralis,the causative agent of whirling disease, was first 

detected in Yellowstone National Park in Yellowstone cutthroat trout 

from Yellowstone Lake in 1998. Since then, efforts have been 

directed at determining the severity and distribution of M cerebralis 

in the lake and its tributaries. 

From 1999 to 2001, a large-scale investigation was conducted 

focusing on histological analysis of by-catch adult Yellowstone 

cutthroat trout and sentinel fry exposures in spawning streams over 

a wide range of water temperatures and flow regimes. Bycatch adults 

were obtained during gillnet operations targeting invasive lake trout 

in Yellowstone Lake. An examination of more than 1500 fish 

revealed the prevalence of the parasite to be approximately 20 

percent in the northern section of Yellowstone Lake to 10 percent in 

the southern arms. 

Dr Todd Koel, supervisory fisheries biologist for the park and 

a whirling disease researcher, oversees much of this investigation. 

Koel monitors waters throughout the park, including the tributaries 

of Yellowstone Lake. He also conducts research projects and 

coordinates the Yellowstone Whirling Disease Research Programme. 

This programme consists of a team of researchers from the park, 

Montana State University, the University of Wyoming, the US 

Geological Survey Western Fisheries Research Centre, the US Fish 

and Wildlife Service-Bozeman Fish Health Laboratory and the states 

of Idaho, Montana and Wyoming. 

The programme has been funded primarily by the Whirling 

Disease Initiative, the Whirling Disease Foundation and the National 

Park Service. 

Pelican Creek is a major spawning tributary for the trout in 

Yellowstone Lake. It became a priority for whirling disease research 

when monitoring data from the investigation revealed that the 

disease had nearly wiped out the cutthroat population. 

The loss of cutthroat trout in Pelican Creek created a gap in the 

natural food chain, with trophic level implications. Birds and bears 

have been required to change their feeding habits (Koel et al, 2005). 

On a social level, anglers have lost a favourite trout fishery which 

was often touted as the best cutthroat fishery in the world. 

▲ 


FINFISH 

WHIRLING DISEASE RESEARCH AT YELLOWSTONE NATIONAL PARK 

Pelican Creek is now closed to angling to allow the cutthroat to 

rebound, and to prevent the potential movement of the parasite into 

other drainages in the park. 

SOLUTIONS THROUGH RESEARCH 

In an effort to understand the ecology of the disease and improve 

management options for Yellowstone cutthroat trout, researchers are 

investigating whirling disease risk in three of the lake’s tributaries. 

This research is being conducted by Silvia Murcia, a researcher for 

the Yellowstone Whirling Disease Research Programme. She is a 

graduate student pursuing a doctorate in fish and wildlife 

management at Montana State University-Bozeman. 

Under the advice of premiere whirling disease researcher Dr Billie 

Kerans, Murcia’s research focuses on spatio-temporal variation in 

whirling disease risk to the Yellowstone cutthroat trout in three 

spawning tributaries of Yellowstone Lake: Pelican Creek, Clear Creek 

and the Yellowstone River. 

One puzzling aspect of this issue is why the problem is so severe 

in Pelican Creek. Murcia postulates that the disease severity results 

from a combination of environmental factors such as naturally 

occurring high water temperatures, low flow regimes, movement of 

bison and elk adding organic material to the water, and angler 

movements. 

These are some of the factors contributing to a warm, silty habitat 

ideal for tubificid and whirling disease proliferation. Murcia’s 

research, which began in 2001, analyses whirling disease presence in 

sentinel and wild-reared Yellowstone cutthroat fry by testing for 

parasite DNA using polymerase chain reaction (PCR) analyses and 

evaluating infection severity by histology. For potential correlations 

to disease prevalence and severity, she also looks at the physical and 

chemical features of the study streams. 

To establish the infection risk among wild native cutthroat, 

Murcia is examining current and historical adult trout spawning 

data to assess the start, peak and end dates of spawning, and 

approximate adult cutthroat mortality after spawning. She hopes her 

research will answer questions regarding fish health and diagnostic, 

management and control methods for whirling disease in native 

cutthroat trout and other vulnerable salmonids. 

The results from her research and the larger-scale investigation 

should assist the park and other regional fisheries managers to 

understand and control whirling disease in a variety of stream types. 

Quantification of environmental characteristics preferred by 

Mcerebralis in the Yellowstone Lake basin will assist in predicting 

probable high-risk sites for infection. Of particular concern are 

tributary basins with landscape-level characteristics similar to 

Pelican Creek, such as the Beaverdam, Trail and Chipmunk Creeks 

in the remote southern and southeastern arms of Yellowstone Lake. 

Murcia and Dr Kerans will use this data to develop a whirling 

disease risk assessment model that could be applied to a range of 

watersheds across the Intermountain West. The goal is to provide 

fish biologists and managers with risk assessment tools to identify 

management actions to reduce disease risk, increase public 

awareness and lessen the chances of this non-native pathogen 

invading other systems. 

PART II: FILLING IN THE GAPS 

Another student of Dr Kerans, Julie Alexander, is currently 

completing research on Pelican Creek and other tributaries with 

variable whirling disease risk (2004 to 2007). 

Alexander’s work complements Murcia’s by investigating the 

ecology of the oligochaete host, Tubifex tubifex.She is examining the 

potential for using high-resolution thermal imagery and habitat 

characteristics to detect high tubificid abundance and possible “hot 

spots” of M cerebralis infection. 

Alexander is pursuing her PhD in biology with a focus on 

parasite-mediated T tubifex ecology. The objectives of her study are 

to quantify 

Mcerebralis 

infection risk in 

Pelican Creek 

using Ttubifexand 

sentinel fish exposures 

to measure variation 

among tubificids and habitat, 

and to assess the potential for 

developing a tool for detecting T tubifex 

and M cerebralis in Pelican Valley, using a 

combination of remotely sensed and 

habitat data. 

Alexander determined the distribution 

of M cerebralis using infection prevalence 

THE PARASITE M CEREBRALIS 

DIGESTS CARTILAGE AND 

CAN CAUSE SEVERE 

SKELETAL DEFORMITIES 

in tubificids collected along the length of Pelican Creek and adjacent 

tributaries, and infection prevalence and severity in sentinel fish. 

Habitat characteristics known to influence M cerebralis infections 

were measured and compared to tubificid data. Relationships 

among infection prevalence, tubificids and habitat were compared to 

remotely sensed thermal data from the NASA Atlas sensor. 

Alexander found that although M cerebralis and tubificids had 

non-uniform distributions, tubificids in more than 90 percent of 

sampling locations were infected with the parasite. These intense 

infection levels in Pelican Creek made it nearly impossible to draw 

conclusions regarding the parasite’s ability to establish and 

proliferate; therefore, Alexander’s study area has expanded to cover 

11 nearby cutthroat spawning tributaries in addition to the highly 

infected Pelican Creek. 

Another component of Alexander’s investigation involves 

documenting actinosporean varieties and numbers that may be 

present. Actinosporeans, the waterborne spore phase of the parasite 

expelled by the worm host, have presented yet another mystery to 

researchers in the park. In 2001, collaboration with the US Geological 

Survey Western Fisheries Research Centre showed that 20 of 3037 

tubificids collected in Yellowstone National Park released actinospores. 

Molecular analyses indicated that none were M cerebralis.The 

team is now interested in determining what other myxozoans are 

present in tributaries within the park. If there are new and different 

myxozoans in the system, the potential for new and different 

problems, either affecting fish or other living parts of the system, 

creates an additional management concern. 

Alexander’s field work is expected to fill gaps identified by the 

principal investigators, Drs Kerans and Koel. The results are hoped 

to further explain the effects of variation in host ecology, assemblage 

community and habitat on whirling disease risk in Yellowstone 

cutthroat trout. 

The National Park Service and many other organisations in the 

United States are working to restore native salmonids. Knowledge of 

the relationships among the environment, tubificid susceptibility 

and whirling disease risk could improve the prioritisation process of 

stream restoration and increase the probability of costly restoration 

success. Murcia’s and Alexander’s work will contribute to these 

larger-scale investigations. In addition, this quantitative data should 

improve the ability of managers to carry out risk assessments, 

particularly for native cutthroat trout, in other backcountry areas. 

As whirling disease spreads, techniques for management in these 

areas will be needed, and it is hoped that Yellowstone National Park 

will provide a successful model for such areas. 

For more information, see the Whirling Disease Initiative website 

www.whirlingdisease.montana.edu 


Koel TM, Bigelow PE, Doepke PD, Ertel BD and Mahony DL 2005. 

Non-native lake trout result in Yellowstone cutthroat trout decline 

and impacts to bears and anglers. Fisheries 30. pp10-19 ■ 


NOCARDIA SERIOLAE 

- A CHRONIC PROBLEM 

FINFISH 

BY DR MARK SHEPPARD (SAKANA VETERINARY SERVICES LTD, CANADA) 

This article was first published by Intervet in their Aquatic Animal Health Newsletter 10 (May 2005) 

Marine nocardiosis is a long-term and problematic bacterial 

infection of warm-water fish, and eventually presents itself 

as an underlying debilitating factor in many types of fish. 

Affected fish often have other concurrent or secondary infections. 

Nocardiosis begins as a “silent infection”, developing undetected 

for months in fry or juvenile fish. The duration of the infection is a 

long-term (chronic) phenomenon. Nocardia bacteria multiply 

slowly within fish tissues before any visual symptoms arise, and 

certainly before lethargy and death rates increase. 

The typical outcomes within affected fish populations are 

poorly performing yearling and pre-harvest fish, elevated feed 

conversion rates, emaciation and rising mortality rates near the 

end of the summer. 

CAUSATIVE AGENT 

Many Nocardia species are found in the terrestrial and marine 

environments, but Nocardia seriolae (previously N kampachi) is 

considered the most likely pathogen of Seriola fish. The bacteria do 

not stimulate a septicaemic reaction or an acute immune response. 

Rather, Nocardia is thought to progressively invade (and perhaps 

dwell and multiply inside) various types of fish host cells, 

including white blood cells. 

Relatively limited information about the microbiology, 

chemistry and patho-physiology related to Nocardia is published. 

This may be due to the inherent problems of researching slowgrowing 

microorganisms. 

ABOVE: A CLASSIC NOCARDIAL LESION SHOWING WHITISH-YELLOW 

IRREGULARLY-SHAPED MASSES AT THE BASE OF THE GILL FILAMENTS 

BELOW: A COALESCING CLUSTER OF NOCARDIAL SKIN ABSCESSES. THESE DRY 

ABSCESSES PROTRUDE INDIVIDUALLY OR IN GROUPS, EACH CONTAINING 

MASSIVE NUMBERS OF NOCARDIA BACTERIA. MANY BURST, LEAVING A “DRY” 

YELLOW SKIN ULCER 

TRANSMISSION AND EPIDEMIOLOGY 

The initial exposure of fry to Nocardia is the likely result of the 

fry consuming uncooked fish tissues (live, raw or frozen) or by 

the horizontal transmission of Nocardia from sick fish. 

Amberjack and yellowtail juveniles fed raw fish or moist pellets 

are likely the first to be infected, so the use of raw, low quality 

trash fish should be avoided when rearing fish of any type. 

The infection develops silently as the bacteria multiply slowly 

over months within major organs such as the spleen, kidney 

and liver. 

SPLEEN WITH HUNDREDS OF 1-2MM 

WHITE-YELLOW SPOTS 

Cohabitation with infected or diseased fish is also a contributing 

factor of this disease. Research indicates that yellowtail sharing 

tank space with sick juveniles (previously injected with live 

Nocardia) eventually exhibit internal pathology (white spots in 

their spleens) after three months of cohabitation, yet no external 

visual symptoms are evident. 

On the other hand, the injected cohort fish began dying 

within two weeks of their intraperitoneal injections. Various 

shellfish populations have also been shown (by RT-PCR) to 

contain genetic material indicative of Nocardia and 

Mycobacterium. However, the question remains whether the 

shellfish should be considered an environmental and 

contributing source of these pathogens, or simply accumulators 

of bacteria from affected finfish populations. 

In marine finfish culture, nocardial infections appear to 

▲ 


FINFISH 

NOCARDIA SERIOLAE – A CHRONIC PROBLEM 

progress more quickly during the summer months, when water 

temperatures reach 24˚C or more, but the mortality due to 

Nocardia is more commonly experienced in autumn and early 

winter, perhaps as the fish becomes overwhelmed and its immune 

system wanes. 

CLINICAL SIGNS AND GROSS PATHOLOGY 

The visual symptoms of this disease vary somewhat. The typical 

external lesions are thin fish, skin nodules (focal, multifocal or 

coalescing), skin ulceration, opercular erosion and irregularly 

shaped fleshy white masses at the base of the gill filaments. The 

internal pathology of nocardiosis is easily confused with other 

“white spot-forming” diseases such as mycobacteriosis (“fish 

tuberculosis”) and photobacteriosis (formerly Pasteurella or 

“pseudo-tuberculosis”), especially if mixed infections exist. 

The white-yellow granulomata are usually 1-2mm in size. The 

spots are most obvious in the spleen, kidney and liver, but can be 

found in any tissue. Fish that mount a significant immune reaction 

to the disease eventually “heal” somewhat and exhibit hard black 

spots (melano-macrophage accumulations) in place of the white 

spots in the liver and adipose tissues. Brown-black crusty plaques 

often develop on the dorsal inner surface of the swim bladder. 

COLONIES OF NOCARDIA SERIOLAE 

ISOLATED ON LOWENSTEIN-JENSEN 

SELECTIVE (ANTIBIOTIC) AGAR 

MICROBIOLOGY 

The bacterium is thread-like, beaded and branching. It is variable 

staining when using Gram’s stain and the bacteria are acid-fast 

positive (pink). The culture and isolation of Nocardia is relatively 

easy, yet somewhat tedious. Several types of agar and broth media 

will support nocardial growth, but these media also support the 

growth of other, faster-growing species of bacteria. 

The use of selective antibiotic agar-tube media, such as 

A SPLEEN IMPRINT OR “STAMP” (X1000, ACID-FAST STAIN) SHOWING BRIGHT 

PINK, THREAD-LIKE BRANCHING AND BEADED NOCARDIA SERIOLAE 

Lowenstein-Jensen, is most efficient to isolate Nocardia directly. 

The incubation time may range from four to 10 days depending 

on incubation temperatures of 25˚C to 35˚C. The colonies appear 

dry and “stacked”. The results of in vitro antibiotic sensitivity 

testing tend to be ambiguous and misleading. In general, Nocardia 

appears to be inherently resistant to most commercially available 

antibiotics when challenged in vitro and in vivo. 

DIAGNOSIS AND PRIMARY ON-SITE TESTS 

A thorough visual examination of the fish is always the best way to 

begin an assessment. Feel the skin and body wall for lumps and 

ulcers. Upon cutting through the firm skin nodules, one will find a 

dry, grey-yellow, inspissated abscess. Lift the operculum to look for 

pale gills and irregular whitish lumps at the base of the filaments. 

Gill, kidney or spleen imprints or “stamps” are easily collected 

(in duplicate), dried and stained using Gram’s or an acid-fast stain. 

Five-millimetre sections of the same tissues are helpful for a 

histological diagnosis when preserved in 10 percent buffered 

formalin. 

MANAGEMENT AND CONTROL 

The best prevention and control of this disease would be through 

vaccination. However, Nocardia vaccine development remains 

experimental. To date, I am unaware of the development of a 

commercially available efficacious antigen-adjuvant combination 

that will prevent nocardial infections in fish. Therefore the early 

detection of silent infections among juvenile live fish is the goal. 

However, the efficacy and practicality of detecting sub-clinical 

nocardiosis remains questionable in that the surveillance for 

infection may involve expensive experimental tests such as mucous 

testing by polymerase chain reaction (PCR) and antibody serology. 

The use of drugs to control Nocardia is controversial. 

Environmentally, consumers are not in favour of drug treatments. 

From a fish production viewpoint, it is very difficult to ensure that 

fish consume sufficient volumes of medicated feed to achieve a 

therapeutic daily dose. 

In making the attempt, the fish may reduce their daily food 

intake and slow their weight gain, thus creating another cost to the 

farmer. Overall, the cost-effectiveness of antibiotic therapies to 

control nocardiosis in finfish is debatable. 

Antibiotic doses need to be high, and the duration of treatment 

must be extended to the point that the use of antibiotics is largely 

impractical. That said, it is speculated that the application of two 

prophylactic treatments applied to asymptomatic juvenile fish may 

be useful. Using specific antibiotics that can penetrate fish cells 

(when in high serum concentration) for an extended period of 

time (10 to 14 days) may interfere with in vivo nocardial 

development. 

CONTINUED ON PAGE 28 

▲ 


INNOVATIVE HEALTH SOLUTIONS 

TO GLOBAL AQUACULTURE 

BY EMILIANO RABINOVICH (PEROS SYSTEMS TECHNOLOGIES, MONTREAL, CANADA) 

RESEARCH 

HOW ORALJECT TM WORKS 

The pharmaceutical world has long aspired to be able to orally 

deliver bioactive compounds. The solution, however, has been 

hindered by seemingly insurmountable biological and 

technical limitations. 

According to the chief scientific officer of PerOs, Dr Grant 

Vandenberg, Oralject TM is an answer to the ongoing quest for 

natural methods of delivering safe and non-invasive treatments for 

multiple diseases and other therapeutic applications. 

Oralject TM permits the oral delivery of therapeutic molecules, 

including antigens (vaccines), antibiotics, peptides and 

nutraceuticals, without costly and complicated encapsulation 

systems. Oralject TM is said to be the first means of delivering large 

molecules in a cost-effective, accurate, safe and efficient manner. 

The intensification of livestock production and the increase in 

stocking densities has created new opportunities for disease 

organisms to flourish and threaten the health of both animal 

and human populations. The increasing exploitation of and 

dependency on animal resources has meant that disease risks 

that did not exist or were unthinkable 40 to 50 years ago are 

now commonplace. The housing and living conditions of 

intensively farmed animals such as pigs, poultry and fish provide 

significant exposure to bacteria and viruses greatly enhance the 

risk of disease. 

Oral administration of vaccines and other bioactive substances 

for livestock industries is by far the most sought after method of 

delivery. Oral vaccine delivery requires no change in normal 

animal husbandry or handling, and thus eliminates the stress 

associated with other methods of administration. 

Oral vaccination is the only method suitable for the rapid and 

simultaneous mass immunisation of bioactive compounds to a 

large population, which is essential for preventing and controlling 

outbreaks of disease. 

PerOs has decided to develop and adapt the Oralject TM 

technology to provide solutions in the aquaculture market. 

In 2004 we founded the first Chilean biotechnological 

company specialising in developing aquaculture products for the 

local market. 

PerOs Aquatic was established in the Puerto Montt region of 

Chile, the core of Chilean aquaculture. PerOs Aquatic will 

manufacture, commercialize and provide support for PerOs’ 

different products and become the springboard for 

commercializing the Oralject TM technology throughout the world. 

PerOs Aquatic will build a manufacturing plant and a field 

service office in the Puerto Montt region to support its initial 

commercial activities. 

There is potential to combine Oralject TM with a large variety of 

applications, and PerOs is constantly developing new applications 

for different aquatic species such as tilapia, sea bass and shrimp, 

and for other monogastric species such as swine, poultry and 

companion animals. 

PerOs is working all over the world to develop new applications 

and actively searching for new opportunities. We have conducted 

tests in Canada, USA, Chile and Norway, and plan to start new 

tests in Ecuador, Mexico, Venezuela, Australia and the Southeast 

Asian region. 

ORALJECT TM TECHNOLOGY 

Oralject TM is an innovative oral delivery system for bioactive 

compounds such as vaccines, peptides and antibodies to 

monogastric species (fish, swine, poultry, companion animals and 

potentially humans). 

It is a combination of naturally derived anti-nutritional factors 

that reduce overall digestive capacity, along with those that 

increase intestinal absorption, providing a novel method to 

transport bioactive compounds intact to the sites of intestinal 

absorption and increase intestinal uptake. 

Compounds given orally tend to be broken down by acid and 

enzymes in the digestive tract, thus neutralising their bioactivities and 

consequent benefits. In order for these compounds to be delivered 

efficiently, it is necessary to avoid this intrinsic digestive function. 

Furthermore, a compound’s ability to penetrate the intestinal 

wall varies from one molecule to another, thereby affecting the 

amount and the nature of the bioactive compound that can be 

delivered into the bloodstream. 

Oralject TM can efficiently bypass the enzymatic process by 

feeding a bioactive compound of interest, along with a cocktail of 

factors that temporarily suppress the digestive enzyme function 

and increase gastric pH. This permits intestinal uptake of the 

compound, allowing it to achieve the desired biological effect. 

ORALJECT TM ADVANTAGES 

Oralject TM is said to be very easy to administer, and does not 

require any specialists or specific skills. A single meal is simply 

replaced with Oralject TM .This simplicity opens a new door to 

mass inoculation. However, the key advantage of this technology 

is that it is cost-effective. Regular injection not only requires 

▲ 


COMPANY FOCUS 

INNOVATIVE HEALTH SOLUTIONS TO GLOBAL AQUACULTURE 

AQUACULTURE IN CHILE 

FISH MANAGEMENT IN ACTION 

expensive specialists and equipment, but also generate significant 

indirect costs for producers (estimated to be as high as the direct 

costs) as a result of livestock stress, mortalities, adhesion, necrosis 

and eating disorders. With no needles and a simple 

administration procedure, Oralject TM technology provides a 

straightforward, cost-effective solution that requires only 

minimal human labour, the company says. 

This technology is very flexible and adaptable. The Oralject TM 

delivery platform can be applied to a wide range of bioactive 

compounds in monogastric species, including vaccines, peptides, 

proteins and antibodies. This versatility makes Oralject TM the ideal 

solution for a large variety of applications around the world. 

REGULATORY ASPECTS 

All the compounds of Oralject TM are classified as Generally 

Regarded as Safe, a key advantage that simplifies regulatory 

approval for new applications. 

“During the next few years we will be developing a great variety 

of applications for the aquatic health market in the Americas, 

Europe and Southeast Asia, and we’ll try to consolidate our 

presence in key markets such as Chile and the United States,” says 

the chief executive officer of Per Os, Jean-Simon Venne. 

“Another big step forward will be developing applications for the 

shrimp market due to the large economic losses in this market 

caused by diseases. We are really satisfied with the results obtained 

up to date. In the short run, PerOs will become a global leader in 

drug delivery systems.” 

See www.perosbio.com 

■ 

PerOs Systems Technologies Inc, known as PerOs, 

is a Canadian biotechnology company that develops 

oral drug delivery systems under the name Oralject TM . 

▲ 

CONTINUED FROM PAGE 26 

NOCARDIA SERIOLAE 

– A CHRONIC PROBLEM 

Control and prevention through husbandry and good 

management practices is the best approach for nocardial 

infections. Avoid uncooked fish feeds (live, raw or frozen) when 

rearing fish of any age or type. Feed only dry, cooked feed. Reduce 

shellfish fouling (ie barnacles) on floats and ropes near finfish 

cages whenever possible. Disinfect hands and marine equipment, 

practice strict diving hygiene between pens, farm sites and rearing 

areas, and minimise fish stress as much as possible. 

VIP.AHI04 

KEY REFERENCES 

Fukuda Y 2001. Prefectural disease report - PCR and in vitro 

comparisons of nocardiosis, mycobacteriosis, odan. 11, pp 131-139 

(in Japanese) 

Itano T and Kawakami H 2002. Drug susceptibility of recent 

isolates of Nocardia seriolae from cultured fish. Fish Pathology 37, 

pp 152-153 (in Japanese with English abstract) 

Kusuda R and Nakagawa A 1978. Nocardial infection of cultured 

yellowtail. Fish Pathology 13. pp 25-31 (in Japanese with English 

abstract) 

Miyoshi Y and Suzuki S 2003. A PCR method to detect Nocardia 

seriolae in fish samples. Fish Pathology 38. pp 93-97 

Sako H 1988. Survival of fish pathogenic bacteria in seawater. 

Bulletin of the National Research Institute of Aquaculture 13. pp 45- 

53 (in Japanese with English abstract) 

Sheppard ME 2004, 2005. A photographic guide to diseases of 

yellowtail (Seriola) fish. 64 pages. ISBN 0-920225-14-4, 

0-920225-15-2 ■ 


AQUATIC ANIMAL HEALTH 

AT THE UNIVERSITY OF TASMANIA 

BY DR BARBARA NOWAK (SCHOOL OF AQUACULTURE, UNIVERSITY OF TASMANIA, AUSTRALIA) 

Rapid development of aquaculture has to be 

supported by an increased capability in aquaculture 

teaching and research. Australia recognised this as 

early as the 1980s, when courses were first developed in 

Launceston, Tasmania. These courses became an important 

part of the new University of Tasmania in 1991 and 

undergo a continuous cycle of review and revision to 

ensure their relevance. The School of Aquaculture remains 

the only university school in Australia dedicated to 

teaching all aspects of aquaculture, and is widely 

recognised as a centre for teaching and research excellence. 

In the 1990s it was the National Key Centre for Teaching 

and Research in Aquaculture, and was funded for the 

maximum nine years. 

Today, its status is further strengthened by being part of 

TAFI, the Tasmanian Aquaculture and Fisheries Institute and 

one of the biggest partners in the Cooperative Research 

Centre for Sustainable Aquaculture of Finfish (Aquafin CRC). 

Over the years many students, industry partners, 

researchers and staff have made huge contributions to the 

shape and direction of the school, and graduates are found 

throughout the Australian industry and around the world. 

It is the only place in Australia to offer degrees entirely in 

aquaculture. Students have access to the best on-campus 

aquaculture facilities in Australia, with pilot scale fish and shellfish 

production. The school houses temperate and tropical fish and 

shellfish species, including salmon, trout, barramundi, seahorses, 

prawns, an algal culture and planktonic production unit, marine 

fish and mollusc hatcheries and sophisticated bio-filter systems. 

All academics specialise in the areas they teach and are active 

researchers. The School of Aquaculture maintains strong and 

THE HANDS-ON 

COMPONENT IS ESSENTIAL 

IN AQUATIC ANIMAL 

HEALTH EDUCATION AT 

ALL LEVELS. 

UNDERGRADUATE 

STUDENTS DURING THEIR 

PRACTICAL IN THE 

AQUACULTURE CENTRE 

EXAMINATION OF SALMON 

GILLS FOR GROSS SIGNS OF 

AMOEBIC GILL DISEASE. 

THE WHITE PATCHES 

SUGGEST AN 

ADVANCED 

STAGE OF THE 

DISEASE 

direct links with the aquaculture industry and is believed to be the 

largest base of aquaculture research in the southern hemisphere. 

Aquatic animal health is an integral component of 

undergraduate teaching. The 13-week unit is compulsory for all 

degree students. Disease diagnosis and treatment are discussed, 

with the main emphasis placed on health management. Host, 

environment and pathogen relationships and fish immunology are 

examined. Problem-solving exercises provide case histories for 

various species. Associate degree students complete a more applied 

Fish Health Management unit. This unit provides students with an 

understanding of aquatic animal health issues, including basic 

principles and on-farm disease diagnosis, 

control and treatment. Both units have a 

significant practical component, ranging 

from measuring immune variables to 

investigating diseases. 

In addition to the undergraduate 

courses, short courses are run for 

researchers and fish health professionals. 

The School of Aquaculture runs fish 

histopathology courses twice a year. The 

workshop is designed to suit postgraduate 

students and postdoctoral fellows who are 

interested in learning histopathology, but 

also as an introduction to aquatic animals 

for veterinarian pathologists or as a 

revision for experienced pathologists. 

Classes are taught in small groups of 

about four persons to accommodate 

different levels of experience. Streaming of 

participants according to experience 

increases the opportunity to maximise 

benefits for each group. 

Conference microscopes, slide projectors 

and computer software illustrate fish 

histopathology. The workshop 

programme includes examples from a 

▲ 

TRAINING/RESEARCH 


TRAINING/RESEARCH 

AQUATIC ANIMAL HEALTHAT THE UNIVERSITY OF TASMANIA 

THE TUNA HEALTH WORKSHOP FOCUSES ON INVESTIGATING MORTALITIES AND 

SAMPLE SUBMISSION. INDUSTRY PARTICIPANTS EXAMINE THE EXTERNAL SURFACES OF 

FISH BEFORE DISSECTING AND COLLECTING SAMPLES 

variety of fish species, both marine and freshwater. 

The use of histopathology in disease diagnosis and its use in 

research are also discussed, and participants are encouraged to 

bring their own slides for discussion. Additionally, fish 

immunology, fish parasitology and aquaculture epidemiology 

courses are organised on demand. 

While these short workshops are open to industry participants, 

the School of Aquaculture also organises specialised workshops for 

the aquaculture industry, in particular the salmon and tuna 

sectors. They are sometimes run off-campus, closer to the fish 

farms, to allow industry participants to have easier access. 

These workshops are designed to be practical, and focus on 

issues of interest to the industry, such as the investigation of 

mortalities and submission of samples, stress and health in fish, 

parasites of tuna, use of aquaculture epidemiology in farm 

management and research. 

The school offers a range of undergraduate and postgraduate 

degrees. The one-year Graduate Diploma in Aquaculture would 

suit recently qualified degree graduates or people seeking to retrain 

to follow a new career. 

While most graduate diploma students have a background in 

biological sciences, candidates with other degrees (including 

chemistry, computer science and arts) have successfully completed 

the graduate diploma and are now working in the aquaculture 

industry or are involved in research. 

The graduate diploma can be credited as the course work 

towards a master’s degree by course work and dissertation (total 

two years). A large proportion of masters and honours projects 

address aquatic animal health issues. 

Many PhD students specialise in aquatic animal health, working 

on areas including fish immunology and fish pathophysiology, as 

LIGHT MICROSCOPY IS A CONVENTIONAL TOOL FOR EXAMINING FISH 

SAMPLES. BLOOD SMEARS, MUCOUS SMEARS, TISSUE IMPRINTS AND 

HISTOLOGY SLIDES ARE USED IN AQUATIC ANIMAL HEALTH PRACTICALS 

well as multidisciplinary projects linking health and nutrition, for 

example. While amoebic gill disease is one of the commonly used 

disease models, bacterial diseases and other parasitic conditions 

are also studied. The projects range from field work to laboratorybased 

basic science projects. 

The School of Aquaculture accepts applications for both a 

traditional start in February and a mid-year start in July. Research 

degrees, either MSc or PhD, can be started at any time of the year. 

The next fish histopathology course is scheduled for February 6 to 

8, with another planned for later this year. 

See www.utas.edu.au/aqua 

■

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