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Fishery Biology

Fishery Biology. Fisheries Management. Provide people with a sustained, high, and ever-increasing benefit from their use of aquatic resources Problems - late-1800s - industrial revolution Improved access to fish Improved effectiveness of fishing equipment

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Fishery Biology

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  1. Fishery Biology

  2. Fisheries Management • Provide people with a sustained, high, and ever-increasing benefit from their use of aquatic resources • Problems - late-1800s - industrial revolution • Improved access to fish • Improved effectiveness of fishing equipment • Improved processing and distribution of fish

  3. Problems resulted in: • Overexploitation (overfishing) in many areas • Catch exceeded maximum sustainable yield • Environmental degradation • Populations exhibit decline • Some commercial species driven to or near extinction

  4. Dealing with the problem • Fish culture • Fish rescue • Fishing regulations • A progressive movement

  5. Fish populations served: • Primary purpose - provide food • Secondary purpose - provide economic value • “crops” to be planted, managed, harvested Maximum sustainable yield (MSY) - efficiency

  6. Additions Growth Recruitment immigration Losses Natural mortality Fishing mortality emigration Fish population abundance changes:

  7. Population Dynamics • Led to conclusion that greatest long-term yield of fish achieved by allowing small fish to grow before harvesting them • But no scientific proof!

  8. Ecology and Fisheries • Ecology as a science provided hypotheses, principles, and fisheries provided natural laboratories for testing them

  9. Early Focus of Fisheries Science • Describe, survey fish, etc., in important waters • Determine physicochemical characteristics • Gather fish life history, ecology information

  10. New Data • Confirmed that habitat destruction, overfishing had negative impacts on fish populations • Led to growth of fisheries management, development of most techniques still used today

  11. Recreational Fishing Growth • Demands for regulations on competing commercial harvests • Eliminate markets for commercially caught freshwater predatory fish

  12. Regulation of Recreational Fishing • First highly restrictive, uniformly implemented • Closed seasons, minimum size, equipment restrictions, creel limits (daily catch) • Next changed to uniformly liberal regulations • Now back to stricter regulations

  13. Primary Funding for Inland Fishery Management in U.S. • Federal Aid in Sport Fish Restoration Act (1950) • Dingell-Johnson (D-J) Act • 10% excise tax on specified fishing equipment

  14. Primary Funding for Inland Fishery Management in U.S. • Wallop-Breaux Act (1985) • Expanded range of items taxed (e.g., boat fuel) • Extended funding to marine recreational fisheries • Doubled previous level of funding ($332 million in 1992)

  15. Different Fish Problems in Different U.S. Regions • Pacific NW - Pacific salmon - reduced runs • Reduced future generations

  16. Different Fish Problems in Different U.S. Regions • SE - raising fish in farm ponds • Predator, prey balance for best fishing

  17. Different Fish Problems in Different U.S. Regions • Midwest, Mideast - techniques for removal, control of unwanted fishes • Commercial netting • Chemical fish poisons

  18. Fish Stocking Changes • Initially widespread, promiscuous introductions of fish eggs, larvae • Now more selective stocking, where growth and survival are probable • Raised in hatcheries to larger size for better survival • “put-and-take” stocking of catchable-size fish

  19. Habitat Modifications • Habitat-related limits to fish size, abundance • Improve habitat to remove limits • Add artificial structures to lakes, streams • Build artificial lakes • Farm ponds • Reservoirs

  20. MSY focus changing during last half-century • More than simply maximizing physical yield • Additional concerns • Economic - e.g., aesthetic values • Sociological - e.g., limited access to fishery • Ecological - e.g., multi-species management

  21. Optimum Sustainable Yield • Includes broad range of concerns • Unique management goal for each fishery • More realistic • Recognizes existence of ecosystem, human need diversities • Greatly complicates management

  22. Important additional roles of fisheries management • Habitat management • Instream flow studies • Watershed land use - mitigation • Habitat rehabilitation - streams, wetlands

  23. Important additional roles of fisheries management • Organism management • Single-species vs. multi-species management • Endangered, rare species management • Management of non-harvested species • Prey • Competitors • Aquaculture

  24. Important additional roles of fisheries management • People management • Methods for assessing user demands, values

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