“Population Structure of Medney : Using the mtDNA control region and Cytochrome b

to compare current population to Asian and western Aleutian  stocks

of Steller sea lions (Eumetopias jubatus)”

Jack L. Ward

 John C. Patton

Dr. John W. Bickham

Department of Wildlife and Fisheries Sciences

Texas A&M University

            The Steller sea lion (Eumetopias jubatus) is a marine mammal that has experienced a drastic population decline since the 1970’s.  Medney Island, which contains the only rookery of Steller sea lions in the Commander Islands group, is of particular significance.  That rookery was extirpated in the 1800’s, but was subsequently colonized as an all male haulout site during the early part of the 20^th Century.  In the 1970’s it once again became a rookery, but it’s affinity with Asian populations to the west or Alaskan populations to the east are unclear.  Initial samples taken from Medney in 1992-1993 suggested this stock was of Asian origin. A subsequent sample taken in 2002 suggested instead a stronger Western Aleutian affinity of this rookery. Due to the ambiguity of assignment this study has been undertaken to increase the sample size of sea lions defining this rookery and better determine whether this rookery should be regarded as a member of the Asian stock or one more properly classified with the western stock. Levels of migration among stocks are thought to be low. This study examines the question of migration and possible introgression between the Asian stock and the Western Aleutian stock, and attempts to uncover the populations of origin of this newly established rookery.

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