Inland Fisheries

9.3.3.7 Genetic problems in threatened species

Inbreeding, negative selection and lack of adoption are considered as genetic causes for decline of natural fisheries and lack of recovery, restocking programmes involving hatchery stocks are unlikely to fully solve the problem since these stocks were selected for adaption to hatchery conditions and not to the natural environments. Since genetic variation is a major factor in population which enables species to adapt to the changes in their environment, any loss of genetic variation results in erosion of evolutionary flexibility. This leads to a poorer match of organisms to adapt to the environment increasing the probability of their extinction. The associated severe genetic problems in the small genetically effective population take the form of genetic bottlenecks, genetic drift and accumulation of homozygosity.