Managing Aquaculture Without Antibiotics - Fact, Fiction or Simply a Farce?

Table of Contents

1. Abstract
2. Presentation - Session Objectives
3. Aquaculture is...
4. Focus on Food Aquaculture in.... North America and Europe
5. Antimicrobials in Aquaculture.... Routes of Adminstration
6. Anitimicrobials in Aquaculture... Feed Medicated in Canada
7. Trends in Antimicrobial Usage in Aquaculture
8. Disincentives to Antimicrobial Usage in Aquaculture
9. Conclusions and Summary

Abstract

Aquaculture is a fast-growing sector of agriculture which includes the production, in both fresh and salt-water environments, of fish, molluscs, crustaceans and plants for human food. It also includes the culture and care of numerous aquarium species which come into contact with humans. In the scheme of livestock production technologies, aquaculture is a good-news story with respect to its future reliance on antimicrobials, and there are a plethora of reasons to support this claim. In North America and Europe, there are very few antimicrobials in common veterinary usage, and these are primarily for therapeutic intervention, rather than for prophylactic or growth promotant purposes. Plus, relatively few microbial fish pathogens are zoonotic, especially in the temperate regions of the world. Vaccines are highly effective in managing bacterial diseases which has led to a significant decline in the use of antibiotics over the last decade. Constantly improving husbandry techniques and veterinary care, and voluntary adoption of codes of practice predicated on low, or no, application of antibiotics are also contributing to reduced usage throughout the industry. Genome manipulation strategies may also improve disease resistance, thereby reducing the need for pharmaceutical treatment. Many disincentives also exist to curtail antibiotic usage in aquaculture, including; the marginal cost-effectiveness of their use in disease treatment, the need to be HACCP compliant, plus, growing concern over negatively impacting the 'healthy food' marketing image currently enjoyed by most seafood products. These factors and more, conspire to create a positive outlook for reduced reliance on antibiotic-based management strategies in the future of aquaculture.

Presentation - Session Objectives

• Overview of world aquaculture sector
• Common antimicrobial use practices
• Emerging trends in fish health management
• Predictions on future antimicrobial reliance
• Impacts of change trends

Aquaculture is...

The farming of aquatic organisms, including fish, molluscs, crustaceans and aquatic plants. Products are destined for human food or recreation, the cosmetic and pharmaceutical industries, or as ornamental or companion animals.

Aquaculture Species Produced

• 121 fin-fish species
• 45 molluscan species
• 29 crustacean species
• 13 plant species
• 4 other species

Aquaculture Growth vs. Terrestrial Animal Production: 1984-1997

Aquaculture has been the worlds fastest growing food production sector for over a decade.

Total Aquaculture Growth = 11.1% per year
Total Capture Fishery Growth = 1.5% per year
Total Terrestrial Animal Growth = 3.0% per year

Major Aquaculture Producers, by Total Metric Tonnage

1. China - 24 MMT
2. India - 1.78 MMT
3. Japan - 1.34 MMT
4. Korea - 1.04 MMT
11. USA - 0.44 MMT
12. Chile - 0.37 MMT
13. Norway - 0.37 MMT
14. France - 0.29 MMT
15. Taiwan - 0.27 MMT
16. Spain - 0.24 MMT
17. Italy - 0.22 MMT
18. Ecuador - 0.14 MMT
19. UK - 0.13 MMT
25. Canada - 0.09 MMT

Aquaculture Environments

• Tropical, temperate and subarctic distribution
• Freshwater
• Brackish water
• Saltwater
• Fully closed systems

Focus on Food Aquaculture in.... North America and Europe

Typical Antimicrobial Usage in Aquaculture

• Therapeutic intervention - yes (>90%)
• Vaccine breakdown - yes
• Prophylactic treatments - rarely
• Control shipping disease - no
• Growth promotion - never

Antimicrobials Approved in Canadian Aquaculture - 1999

• Florfenicol (Aquaflor)*
• Sulfadiazine + Trimethoprim (Tribrissen)*
• Sulfadimethoxine + Ormetoprim (Romet 30)*
• Oxytetracycline (Terramycin-AQUA)**

* By prescription only
** MIB, Over the counter

Antimicrobials Approved in U.S.A. Aquaculture 1999

• Oxytetracycline (Terramycin-AQUA)
• Sulfadimethoxine + Ormetoprim (Romet 30)
• Sulfamerazine (not distributed)

Antimicrobials in Aquaculture.... Routes of Adminstration

• Oral administration with feed (>90%)
• Injection - primarily in broodfish
• Water bath exposure - primarily for eggs
• Rarely employ chronic treatment protocols

Anitimicrobials in Aquaculture... Feed Medicated in Canada

• Recent studies by the Department of Fisheries and Oceans Canada, demonstrated less than 1.6% of all feed used in Eastern Canada is medicated
• Similiar results for Western and Central Canada aquaculture regions

Trends in Antimicrobial Usage in Aquaculture

Emerging Health Management Strategies

• Prudent A-M use for therapy only
• Drug rotation
• Vaccines
• Best Management Practices
• Codes of Practice
• Improved Nutrition and Feeding Practices
• Improved husbandry
• Selective breeding and domestication
• Transgenic technology

Vaccines are Highly Effective

• Immersion vaccines for Yersiniosis, Vibriosis, Furunculosis, Edwardsiella and Penaeid multivalent bacterin
• Injectable vaccines for Yersiniosis, Vibriosis, Hitra and Furunculosis

Other Progressive Measures

• Healthy Salmon Program
• HACCP Compliancy

Canadian Healthy Salmon Program

• Industry led by Salmon Health Consortium
• Farm-level control of antimicrobials
• HACCP compliancy
• Record keeping, eduction, verification
• Third pary audits
• Quality Assurance Program

Transgenic Technologies?

Genome manipulation may enhance disease resistance in farmed fish via:

• Diease resistance
• Stress genes
• Environmental tolerance (e.g. anti-freeze)
• Detoxification enzymes
• Viral proteins

Disincentives to Antimicrobial Usage in Aquaculture

• High cost of new product registration
• Marginal cost effectiveness of treatments
• Clearance times required
• HACCP regulations
• Export trade constraints
• International trade issues
• Environmental concerns and regulations
• Other statutory monitoring programs
• Impace on wholesome market image
• Resistance factors

Emerging Problems?

• Imports from developing countries - food as well as tropical species
• Ornamental fish exposure

Conclusions and Summary

Aquaculture is a Good-News Story

• Future use should continue to decline
• Antimicrobials will be a necessary tool to combat aquaculture diseases for the foreseeable future
• When Costs>Benefits = Reduced Use

Acknowledgements

• Dr. Myron Roth, Salmon Health Consortium
• Ms. Rosalie Schnick, Joint Subcommittee on Aquaculture