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Bycatch

Bycatch Fish 323 Structure of lecture Definition Consequences How it happens Solutions Case studies Shrimp turtles Tuna porpoise Vaquita Seabirds *2 Definition Total fishing mortality excluding that accounted directly by the retained catch of target species (OECD,1997). Includes:

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Bycatch

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  1. Bycatch Fish 323

  2. Structure of lecture • Definition • Consequences • How it happens • Solutions • Case studies • Shrimp turtles • Tuna porpoise • Vaquita • Seabirds *2

  3. Definition • Total fishing mortality excluding that accounted directly by the retained catch of target species (OECD,1997). • Includes: • Targeted species that are discarded • Non-targeted species (incl those targeted in other fisheries) • [Ghost-fishing]

  4. Impacts • Threatened species (esp long-lived species with low maximum reproduction) • Reduced abundance of commercial species • Changes in ecosystem function

  5. Scale

  6. Scale • Alaska longline fishery: 10,000-20,000 seabirds per year • Global longline fishery: 1.4 billion hooks catch 50-60,000 Leatherback Turtles per year • Gulf of Mexico shrimp trawl fishery: 2-5 million lb of red snapper per year (compared to 9 million lb in recreational and commercial fisheries)

  7. Repercussions • Bycatch of species protected under the ESA or MMPA may lead to fisheries disruption and even closures (e.g. closure of swordfish fishery off Hawaii). • For targeted species, the TAC should include all fishing mortality – if bycatch is high in other fisheries, there may be no quota left for the targeted fishery. • Attempts to ban imports have led to international trade disputes.

  8. Why does it happen? Fishing gears: • There is potential for bycatch in all gears, but some gears are ‘dirtier’ than others. • Some gears are more selective and/ or allow unwanted fish to be released in good condition.

  9. The dirtiest 20 by-catch fisheries in the world

  10. Bycatch from a shrimp trawl

  11. The cleanest 10

  12. Why does it happen? Discarding of targeted species: • Size regulations • High-grading • Catch and release fisheries

  13. Global marine bycatch/ discards

  14. Gear modifications Short-term (or permanent) area closures Changes in timing of fishing activities, seasonal closures Reduce fishing pressure Bycatch quotas (require observers) Compensatory mitigation Creation of new markets for bycatch species Potential solutions

  15. Need to be: Technically feasible Financially and economically viable Enforceable Potential solutions

  16. Shrimp-Turtle

  17. Tuna-Dolphin

  18. Vaquita

  19. Seabirds

  20. c=control ssl=single streamer line psl=paired streamer line Cooperative research

  21. Compensatory mitigation

  22. Summary • By-catch is ever present in fisheries – it can be reduced, but probably rarely eliminated. • Solutions need to be technically feasible, financially and economically viable, and enforceable – incentives are an important element in eliminating the problem.

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