Sea Otter Conservation Genetics

Conservation genetics is the science focused on the understanding of hereditary processes and mitigating factors that endanger populations at risk of extinction. It is an interdisciplinary specialty in which geneticists explore genetic variation, with the goal of enabling resource managers to better conserve biodiversity. Sea otters offer a unique case for the study and application of conservation genetics because of their documented history of population reduction and recovery from the fur trade of the eighteenth and nineteenth centuries. Population genetic studies using microsatellites and mitochondrial (mt) DNA have found low genetic diversity within modern sea otters compared to those sampled during the fur trade. Many sea otter populations remain fragmented and isolated today, more than 100 years after the fur trade ended, although they maintain historical genetic structuring based on analysis of both pre- and post-fur trade populations. Translocations to augment recovery in areas where sea otters remained absent have resulted in recovery of some of the lost genetic diversity. In addition to studies of genetic diversity, genetic methods such as allozymes, mtDNA restriction fragment-length polymorphism (RFLP) analysis, microsatellites, and direct sequencing have been used to determine genetically distinct populations and stocks to inform management decisions. Newer research on adaptive genetics has investigated portions of the genome responsible for individual and population health, such as the major histocompatibility complex (MHC) and gene expression, reporting varying levels of diversity and expression. Here we review the methods and results of past genetic studies, explore future directions for sea otter conservation genetics, and discuss the implications of genetic research for the long-term conservation of sea otter populations.