Managing translocations of aquatic species

The translocation of aquatic organisms is an issue of increasing concern. In assessing the genetic risks from translocations, a primary distinction should be made between translocation for the purpose of aquaculture and translocation for the purpose of stock enhancement. When translocation is for aquaculture, the question of interest is: what is the maximum level of escapes that should be permitted, beyond which there is an unacceptable probability of adverse genetic effects upon the natural population? Risk minimization should concentrate on management solutions that reduce escapes from aquaculture facilities. When translocation is for stock enhancement, the question of interest is: what is the maximum level of genetic differences between hatchery and wild stock that should be permitted, beyond which there is an unacceptable probability of adverse genetic effects upon the natural population? Risk minimization should concentrate on hatchery management procedures that reduce genetic differences in fitness traits between hatchery stock and wild stock from the proposed recipient population. Where translocation poses a significant risk of adverse genetic changes, then a monitoring programme should be put in place, linked to a policy that prescribes management actions for the range of possible outcomes from the monitoring. The main limitation to our ability to develop an effective risk assessment and monitoring process is our lack of understanding of how the interaction between genetically different stocks affects the genetic basis of quantitative fitness traits that adapt organisms to their local environment.