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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 Improved processing and distribution of fish 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 Dealing with the problem Fish culture Fish rescue Fishing regulations A progressive movement Fish populations served: Primary purpose - provide food Secondary purpose - provide economic value – “crops” to be planted, managed, harvested Maximum sustainable yield (MSY) - efficiency Fish population abundance changes: Additions – – – Growth Recruitment immigration Losses – – – Natural mortality Fishing mortality emigration 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! Ecology and Fisheries Ecology as a science provided hypotheses, principles, and fisheries provided natural laboratories for testing them Early Focus of Fisheries Science Describe, survey fish, etc., in important waters Determine physicochemical characteristics Gather fish life history, ecology information 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 Recreational Fishing Growth Demands for regulations on competing commercial harvests Eliminate markets for commercially caught freshwater predatory fish 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 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 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) Different Fish Problems in Different U.S. Regions Pacific NW - Pacific salmon - reduced runs – Reduced future generations Different Fish Problems in Different U.S. Regions SE - raising fish in farm ponds – Predator, prey balance for best fishing Different Fish Problems in Different U.S. Regions Midwest, Mideast - techniques for removal, control of unwanted fishes – – Commercial netting Chemical fish poisons 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 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 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 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 Important additional roles of fisheries management Habitat management – – – Instream flow studies Watershed land use - mitigation Habitat rehabilitation - streams, wetlands 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 Important additional roles of fisheries management People management – Methods for assessing user demands, values