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.