GENETIC PROBLEMS OF HATCHER-REARED PROGENY RELEASED INTO THE WILD, AND HOW TO DEAL WITH THEM

Long-overdue concerns about the genetic effects of releases of hatcher y-reared progeny on wild populations have been increasingly addressed during the past 20 yrs. Because of an extensive history of translocati on and culture, much attention in both of these categories has focused on salmonid species. Native salmonids have been indirectly affected b y translocations through such activities as induced overharvest in sto ck mixtures, disease introductions, and displacements resulting in fra gmented populations with reduced numbers and, commonly, localized exti nctions. Direct genetic effects through introgressive hybridizations o f translocated salmonids have resulted in replacement of many native p opulations by hybrid swarms. Genetic effects from salmonid culture hav e led to losses of variability, both within the cultured populations a nd between the total cultured and wild populations, and to adaptive di vergences distinguishing cultured and wild populations. Examples are p rovided that show that the overall salmonid experience is directly rel evant to marine culture as well, although special considerations deal with the lower among-population diversity and greater fecundity often found in marine species. As marine enhancement programs inevitably exp and identifying and preserving natural populations are concerns common to harvest, management, and conservation interests. Coordinated rathe r than polarized approaches to these concerns best serve all parties a s well as the irreplaceable resources.