GERMPLASM REPOSITORIES CAN PROVIDE A NECESSARY TOOL FOR RECOVERY PROGRAMS OF IMPERILED FISHES

Recovery programs for endangered or threatened species require a combination of various conservation tools such as status assessment, legislation, habitat restoration and management, translocation, and captive breeding. However, limitations of those tools challenge implementation of such programs. For example, long-term efforts such as habitat restoration can take decades, but population sizes and genetic diversity of concerned species can continue to decline in nature before full restoration. Shorter-term efforts such as captive breeding are at risk due to disease outbreaks, administrative discontinuity, high costs, and inbreeding depression. Repositories of cryopreserved germplasm can become a valuable addition to the conservation toolbox to address these challenges by preserving germplasm for future use at a relatively low cost, ensuring integrity of genetic diversity, enabling genetic assessment, and enhancing captive breeding. This tool has been used to improve diversity in recovery of endangered mammals such as the black-footed ferret (Mustela nigripes). However, it has been neglected in conservation programs of imperiled fishes. For example, in 86 current recovery plans of endangered or threatened fishes developed by the U.S. Fish & Wildlife Service, only 2 mention cryopreservation, and that was for research purposes. We have developed a recovery plan using Redtail Splitfin (Xenotoca eiseni) as a model species to demonstrate a comprehensive strategy to couple germplasm (sperm) repositories with conventional conservation tools. Sperm from X. eiseni from wild populations can be cryopreserved on-site in French straws, and the straws shipped to a central repository (Fig. 1). When wild populations are brought to hatcheries, sperm from these stocks can be cryopreserved, genetically characterized, and used when necessary to maintain desired levels of genetic diversity and reduce inbreeding of broodstocks. When historic or translocation habitats are ready, germplasm can be incorporated into live populations in hatcheries for introduction to the habitats. Successful recovery requires a practical conservation plan as well as strong collaborations among people and agencies with specialized expertise and function. A calculator model was developed to assist linkage of expertise with germplasm repositories. Based on desired levels of heterozygosity, inbreeding, and effective population size, the brood sizes from cryopreserved germplasm can be calculated for incorporation into captive stocks can be calculated. For example, if 500 offspring from germplasm repositories are desired per year for 50 years, sperm of 174 males from wild populations need to be cryopreserved into 156 straws, and 6 straws need to be thawed and used to inseminate 125 females per year (if 20% of females are able to produce 20 offspring). Protection and characterization of genetic resources can be integrated into conservation programs through development of interaction with germplasm repositories, and expanded strategies for genetic management.