Gena Bentall

University of Santa Cruz
Center for Ocean Health,
Long Marine Lab

Monterey Bay Aquarium
Sea Otter Research and Conservation
886 Cannery Row
phone:  (831) 644-7545
fax:    (831) 648-4989
GBentall@mbayaq.org

How does food abundance affect behavior and morphology in Southern sea otters?

My current work focuses on the ways in which abundance of prey is reflected by the behavior and morphology of the southern sea otter (Enhydra lutris nereis). An understanding of the affect of food availability on sea otter behavior can be a useful tool when evaluating the status of sea otter populations. The southern sea otter, ranging from Ano Nuevo south to Point Conception, has failed to recover at a predicted rate since attaining protected status in 1911. The slow rate of growth became more pronounced in the mid 1990's and included a period of population decline which has been attributed to increased mortality. While disease has been strongly implicated as a proximate cause of this mortality it is unclear to what extent food abundance is contributing to the limited population growth. Recent work done by Dr. Tim Tinker has revealed patterns of foraging behavior that may be correlated to high sea otter population density and the associated reduction in prey abundance. Further evidence is needed to support this hypothesis: are these patterns present when sea otters have plenty to eat? A sea otter translocation project carried out in the late 1980's has provided a unique opportunity for comparative study. San Nicolas Island, the most remote of southern California's Channel Islands, was the relocation site for 140 sea otters during 1987-1990. Currently, the island is home to 30-40 sea otters, which have access to abundant prey resources. The focus of my research is to compare food related indices such as body condition, foraging behavior and activity budgets between the low otter density San Nicolas Island and the high density range center population in the San Simeon region of central California. My goals are twofold: 1) to obtain further evidence that food limitation is driving behavioral polymorphisms in the central California sea otter population and 2) to gain further insight into the factors limiting growth in the southern sea otter. To date, the results from this comparative study have provided the strongest evidence to date that foraging polymorphisms in sea otters are linked to population density and food abundance. Perhaps of utmost importance, the behavior and morphology of central California sea otters are consistent with a food limitation population.

University of California Santa Cruz

• M.A. Ecology and Evolutionary Biology, 2005
  • Major Focus: Sea otter foraging ecology
  • Thesis: Morphological and behavioral correlates to population status in the southern sea otter, Enhydra lutris nereis : a comparative study between central California and San Nicolas Island.

Oregon State University, Corvalis

• B. S. Zoology, 2001.

San Nicolas Island, Channel Islands, CA