Can stock enhancement enhance stocks?

Successful stock enhancement or restocking requires a thorough understanding of the ecological processes that provide a potential for stocking within different ecosystems, i.e. determine which factors define the potential for stocking, such as population dynamics, economic cost-benefits, fisheries management and socio-economic impacts. Stocking is not simply a question of aquaculture logistics (i.e. the ability to produce a sufficient number of fry relative to the magnitude of the natural recruitment within the system), nor should it be a new outlet for aquaculture production. Quantitative targets should be set and the expected performance of the stocking tested. Potential loopholes, such as post-release mortality and habitat requirements related to the release, should be examined and resolved. If properly managed, stocking may lead to an increase in population, contribute to the local fishery and/or lead to an increase in the spawning stock biomass. The criteria for stocking are discussed in this paper using examples from flatfish and cod stocking programmes within specific ecosystems.