Marine fish stock enhancement: status, potential and constraints
Open-water stocking Reservoirs –Salmon, trout, whitefish, striped bass Lakes and streams –Largemouth bass, channel catfish Coastal seas –Ranching anadromous species –Marine fish
Potential for marine fish stock enhancement in North Carolina Summer flounder (Paralichthys dentatus) Southern flounder (P. lethostigma) Red drum (Sciaenops ocellatus) Species of primary interest
Approaches to restoring a fishery Restrict harvesting – Recreational and commercial quotas Restore degraded nurseries – Remove sources of pollution Enhance stock – Release hatchery-produced fish
What is the status of the flounder and red drum fisheries in NC? Landings have declined in recent years. Stocks are far below historical levels. Management plans are in place for summer flounder and red drum, but not southern flounder.
When does stock enhancement make sense, and would it replace traditional management techniques? Declining fishery. Growing demand. Excess carrying capacity. Ineffective management strategies. Built-in environmental safeguards.
What are the concerns about stock enhancement in the marine environment? Diluting genetic diversity of wild stock. Exceeding carrying capacity of receiving waters. Introducing disease. Undermining management practices. Behavioral deficits
Are conditions favorable for stocking summer flounder and red drum in NC? Stocks are depressed. Demand for flounders strong, but uncertain for red drum. High inter-annual variation – in recruitment levels. – in distribution of recruits. Management targets for summer flounder have not been met.
Favorable conditions in NC for stock enhancement NC’s extensive coastline provides good habitats for young fish. Fishing industry is important. –Legislators and community are receptive. –Gear available to monitor and document results of stocking effort. University system with faculty pursuing marine aquaculture and stock enhancement.
Challenges to stock enhancement in NC NC in on northern edge of ecological range for red drum and southern flounder. NC’s large systems of sounds and sound-ocean interactions make tracking stocked fish difficult. Extensive net fishing in sounds threatens stocked fish.
Is there stock enhancement experience elsewhere to build on? Japan –Japanese flounder U.S. –Texas and S. Carolina - Red drum –Florida - Snook, Red drum –Hawaii - Grey mullet and Pacific threadfin
Japanese experience: Factors important for successful stocking Timing of release. Size of released fish. Food availability. Cooperation from fishermen.
Texas experience: Factors contributing to success of red drum stock enhancement Banned nets in coastal waters. Enforced stringent harvest regulations. Rewards to fishermen for reporting tagged fish. Education programs. Strengthened habitat protection.
What are the major elements in designing a responsible stock enhancement program? Strong research component – Multidisciplinary approach. Program framework –Develop reliable hatchery as a base. Build public acceptance. –Educational programs.
Program framework Prioritize species. Identify genetic and harvest objectives. Incorporate genetic, disease and health mgt. Develop reliable hatchery. Use pilot releases to identify optimum release protocols. Mark hatchery fish to assess stocking impact. Consider ecological impacts.
Program framework Identify economic and policy guidelines. Use adaptive management to integrate new information. Make long-term commitment.