Hopkins Marine Station Student Paper

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Title: Activity time budgets as indicators of the status of the sea otter population in California
Student Author(s): Underwood, Karen E.
Faculty Advisor(s): Estes, James
Pearse, John
Pages: 30
Location: Senior Thesis UC Santa Cruz
Keywords: Enhydra lutris, Hopkins Marine Life Refuge, HMLR
Abstract: The sea otter population in California faces the increasing threat of oil pollution, as well as conflicts with man for food resources. Management of the sea otter is needed, but before a management plan can be implemented, the status of the sea otter must be known. Activity time budgets are one way of assessing population status.
Samples of sea otter daily activity were taken over a ten month period along two sections of the Monterey Peninsula. One section had been sampled in a similar study several years earlier. Results from this previous study suggested the population was below its carrying capacity. Results from my study proved to be nearly identical, indicating the population is stable. Comparisons of time budgets with Alaskan populations of known status indicate the populations in Monterey and at the edge of the range are not at equilibrium density, yet other studies suggest that the population may be food limited. Because of the inconsistancy in data, the population status cannot be determined at this time with certainty.
Distinct feeding peaks occurred in the early morning and evening, which also corresponded with data from previous studies. Peaks and lulls in feeding activity were indicative of differential food availability. No significant differences in activity time budgets or diurnal activity patterns were found between the two areas sampled in this study.