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Effects of research disturbance on the behavior and abundance of Steller sea lions (Eumetopias jubatus) at two rookeries in Alaska

Authors

  • Kenady Wilson,

    1. National Marine Mammal Laboratory,
      Alaska Fisheries Science Center,
      NOAA Fisheries,
      7600 Sand Point Way NE,
      Seattle, Washington 98115, U.S.A.
      E-mail: kcr13@duke.edu
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    • Current address: Nicholas School of the Environment, Duke University, PO Box 90328, Durham, North Carolina 27708, U.S.A.

  • Lowell Fritz,

    1. National Marine Mammal Laboratory,
      Alaska Fisheries Science Center,
      NOAA Fisheries,
      7600 Sand Point Way NE,
      Seattle, Washington 98115, U.S.A.
      E-mail: kcr13@duke.edu
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  • Erin Kunisch,

    1. National Marine Mammal Laboratory,
      Alaska Fisheries Science Center,
      NOAA Fisheries,
      7600 Sand Point Way NE,
      Seattle, Washington 98115, U.S.A.
      E-mail: kcr13@duke.edu
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    • Current address: Department of Fisheries and Wildlife, Marine Mammal Institute, Oregon State University, 2030 SE Marine Science Dr., Newport, Oregon 97365, U.S.A.

  • Kathryn Chumbley,

    1. National Marine Mammal Laboratory,
      Alaska Fisheries Science Center,
      NOAA Fisheries,
      7600 Sand Point Way NE,
      Seattle, Washington 98115, U.S.A.
      E-mail: kcr13@duke.edu
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  • Devin Johnson

    1. National Marine Mammal Laboratory,
      Alaska Fisheries Science Center,
      NOAA Fisheries,
      7600 Sand Point Way NE,
      Seattle, Washington 98115, U.S.A.
      E-mail: kcr13@duke.edu
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Abstract

We examined the effects of research disturbance on the behavior and abundance of Steller sea lions (Eumetopias jubatus) at rookeries on Marmot and Ugamak Islands in Alaska. During 3 of 6 yr, researchers intentionally drove all adult and juvenile sea lions off at least part of the beach in order to permanently mark and measure sea lion pups. The research disturbance occurred after the majority of females had bred and when most pups were 1 mo old. We used generalized linear models to determine the relationship between research disturbance and sea lion behavior or abundance. Research disturbance was related to changes in the proportion of sea lions exhibiting two to three of nine behavior metrics: agonistic and resting females and active males at Marmot, and active and resting males and females at Ugamak. Model results indicated that changes lasted between 3 and 20 d depending on the sex, behavior, and rookery. Inclusion of research disturbance into Marmot abundance models did not improve the fit to the data, if variability between years was permitted. Optimally timed, low-frequency research disturbance did not appear to have long-term effects on sea lion behavior or abundance and was largely associated with changes that were similar to natural variation.

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