Graduate Thesis Or Dissertation

An Ecological Assessment of a Potential Sea Otter (Enhydra lutris) Reintroduction to the Oregon Coast

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  • Sea otters (Enhydra lutris) used to exist along coastlines throughout much of the North Pacific Ocean. During the Maritime Fur Trade, sea otters were extirpated from much of their historic range, including Oregon. There is renewed interest in reintroducing sea otters to Oregon. Managers seek improved understanding of the potential for coastal habitats to support sea otter populations, factors likely to affect reintroduction success, and how sea otters may change nearshore ecosystems if brought back. These uncertainties were addressed by adapting and applying a recently developed model of habitat-specific carrying capacity for southern sea otters to estimate spatial variation in potential sea otter abundance (at equilibrium) in Oregon. These predictions were spatially related to human activities to investigate potential human interactions. A systematic review and meta-analysis was conducted to quantify direct and indirect effects of sea otters on nearshore ecosystems. A total carrying capacity of 4538 (95% CI: 1742-8976) sea otters was predicted to exist in Oregon based on available habitats. Oregon’s commercial red sea urchin fishery was expected to have a relatively high interaction potential with sea otters, while the commercial Dungeness crab fishery was not. Meta-analysis results confirmed common ecological effects associated with sea otter presence, including 58% (95% CI: -71%, -40%), 58% (95% CI: -82%, -2%), and 23% (95% CI: -31%, -14%) reductions in prey biomass, density, and size, respectively. These findings were supplemented with a 152% (95% CI: +60%, +297%) increase in kelp density. These findings inform managers as they decide whether they will proceed with a sea otter reintroduction to Oregon, and, importantly, demonstrate sea otters could once again survive in Oregon, but managers should consider how human activities may influence reintroduction success and how sea otters may change ecosystems if reintroduced.
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Peer Reviewed
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  • Existing Confidentiality Agreement
Embargo date range
  • 2020-01-06 to 2020-01-16



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