9314 - Laserfiche WebLink

Home Browse Search

may be affected by these risks and the hatchery activities that may cause the risks are summarized in Box 4. C. General Guidelines for Reintroduction of Captive-Reared Fish. Suitable habitat must be available in areas that are proposed for reintroduction to increase the likelihood of success. The reasons for holding, rearing, and stocking endangered and candidate fishes are summarized in Box 5. Criteria for holding, rearing, or stocking captive-reared fish, and action required are provided in Box 6. General guidelines for preparing reintroduction/augmentation plans are summarized in Box 7. Reasons for Maintaining Genetic Diversity in Captive Propagation Programs. The major objective of a captive propagation program is to develop broodstocks and produce offspring that have genetic characteristics similar to those of the founding population. The purposes of a captive propagation program are; (1) to facilitate recovery (i.e., development of self- sustaining populations), and (2) to maintain artificial genetic refugia for fish species or stocks that may be susceptible to extinction. Managing captive populations to maintain existing natural genetic diversity preserves future options for effective management and recovery of the taxon by fish and wildlife managers (Ralls and Ballou 1992; Thomas 1990). The natural genetic diversity within a population is associated with its evolutionary history and is important for adaptation, long-term survival, and maximum productivity in the wild. Protecting genetic diversity within hatchery broodstock prevents artificial selection, inbreeding, and genetic drift which frequently occurs in hatchery programs (Allendorf 1993). The concept of "maximally protecting genetic diversity" within a hatchery stock assumes that a sufficient number of randomly sampled individuals from the appropriate donor stock were used. The broodstock will then reflect the genetic characteristics of the donor stock. Proper broodstock development during the founding phase is fundamental in the recovery of species. The importance of maintaining detailed and accurate records cannot be overemphasized. Records should include the origin, genetic profile, and unique identifying number of each adult broodfish as well as its production record and progeny performance. Genetic characteristics of broodstocks and progeny must be known so that reintroduction or augmentation efforts can be monitored and evaluated to determine survival of hatchery-reared fish and their interaction with wild stocks (Gauldie 1991; Hynes et al. 1981). Broodstock Development. The first priority for obtaining founders for a broodstock is to only use fish from the appropriate wild stocks or populations. Selection will be made using acceptable breeding strategies that will maintain genetic diversity similar to the wild stock (Kapuscinski et al. 1993). If the stock or population has been 15