Influenoe of sea otters on soft-bottom prey communities in southeast Alaska

Abstract Background Reintroducing predators is a promising conservation tool to help remedy human-caused ecosystem changes. However, the growth and spread of a reintroduced population is a spatiotemporal process that is driven by a suite of factors, such as habitat change, human activity, and prey availability. Sea otters (Enhydra lutris) are apex predators of nearshore marine ecosystems that had declined nearly to extinction across much of their range by the early 20th century. In Southeast Alaska, which is comprised of a diverse matrix of nearshore habitat and managed areas, reintroduction of 413 individuals in the late 1960s initiated the growth and spread of a population that now exceeds 25,000. Methods Periodic aerial surveys in the region provide a time series of spatially-explicit data to investigate factors influencing this successful and ongoing recovery. We integrated an ecological diffusion model that accounted for spatially-variable motility and density-dependent population growth, as well as multiple population epicenters, into a Bayesian hierarchical framework to help understand the factors influencing the success of this recovery. Results Our results indicated that sea otters exhibited higher residence time as well as greater equilibrium abundance in Glacier Bay, a protected area, and in areas where there is limited or no commercial fishing. Asymptotic spread rates suggested sea otters colonized Southeast Alaska at rates of 1–8 km/yr with lower rates occurring in areas correlated with higher residence time, which primarily included areas near shore and closed to commercial fishing. Further, we found that the intrinsic growth rate of sea otters may be higher than previous estimates suggested. Conclusions This study shows how predator recolonization can occur from multiple population epicenters. Additionally, our results suggest spatial heterogeneity in the physical environment as well as human activity and management can influence recolonization processes, both in terms of movement (or motility) and density dependence.

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Trends and Carrying Capacity of Sea Otters in Southeast Alaska

Journal of Wildlife Management ◽

10.1002/jwmg.21685 ◽

2019 ◽

Vol 83 (5) ◽

pp. 1073-1089 ◽

Cited By ~ 7

Author(s):

M. Tim Tinker ◽

Verena A. Gill ◽

George G. Esslinger ◽

James Bodkin ◽

Melissa Monk ◽

...

Keyword(s):

Carrying Capacity ◽

Sea Otters ◽

Southeast Alaska

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DIET AND FORAGING BEHAVIOR OF SEA OTTERS IN SOUTHEAST ALASKA

Marine Mammal Science ◽

10.1111/j.1748-7692.1993.tb00441.x ◽

1993 ◽

Vol 9 (2) ◽

pp. 168-181 ◽

Cited By ~ 28

Author(s):

Rikk G. Kvitek ◽

C. Edward Bowlby ◽

Michelle Staedler

Keyword(s):

Foraging Behavior ◽

Sea Otters ◽

Southeast Alaska

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Did Tlingit Ancestors Eat Sea Otters? Addressing Intellectual Property and Cultural Heritage through Zooarchaeology

American Antiquity ◽

10.1017/aaq.2019.101 ◽

2020 ◽

Vol 85 (2) ◽

pp. 202-221

Author(s):

Madonna L. Moss

Keyword(s):

Alaska Native ◽

Marine Ecosystem ◽

Keystone Species ◽

Sea Otter ◽

Sea Otters ◽

Southeast Alaska ◽

The North ◽

Commercially Important ◽

The 1960S ◽

The North Pacific

The maritime fur trade caused the extirpation of sea otters from southeast Alaska. In the 1960s, sea otters were reintroduced, and their numbers have increased. Now, sea otters are competing with people for what have become commercially important invertebrates. After having been absent for more than a century, the reentry of this keystone species has unsettled people. Although some communities perceive sea otters as a threat to their livelihoods, others view their return as restoration of the marine ecosystem. The federal Marine Mammal Protection Act authorizes any Alaska Native to harvest sea otters for subsistence provided that the harvest is not wasteful. Some people are seeking to define “traditional” Tlingit use of sea otters as not only using their pelts but consuming them as food, but some Tlingit maintain they never ate sea otters. This project analyzes the largest precontact archaeological assemblage of sea otter bones in southeast Alaska, with the benefit of insights gained from observing a Tlingit hunter skin a sea otter to infer that Tlingit ancestors hunted sea otters primarily for pelts. The extent to which other Indigenous peoples of the North Pacific consumed sea otters as food deserves investigation, especially as sea otters recolonize their historic range.

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Impacts of sea otter (Enhydra lutris) predation on commercially important sea cucumbers (Parastichopus californicus) in southeast Alaska

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0025 ◽

2013 ◽

Vol 70 (10) ◽

pp. 1498-1507 ◽

Cited By ~ 15

Author(s):

Sean D. Larson ◽

Zachary N. Hoyt ◽

Ginny L. Eckert ◽

Verena A. Gill

Keyword(s):

Sea Cucumber ◽

Inverse Relationship ◽

Population Survey ◽

Fishery Management ◽

Sea Otter ◽

Enhydra Lutris ◽

Sea Otters ◽

Sea Cucumbers ◽

Southeast Alaska ◽

Commercially Important

Sea cucumbers (Parastichopus californicus), which are an important commercial, subsistence, and ecological resource, are negatively affected by an expanding sea otter (Enhydra lutris) population in southeast Alaska. A few hundred sea otters were reintroduced into southeast Alaska in the late 1960s after their extirpation during the 18th and 19th century fur trade. In the ensuing decades after recolonization, the sea otter population grew exponentially in number and distribution, and sea cucumbers declined in density in areas with otters, suggesting an inverse relationship between sea otter numbers and sea cucumber density. We evaluated the interaction and effects of sea otters on sea cucumbers using sea otter foraging observations, sea otter population survey data, and sea cucumber density data. Our results indicate that sea cucumber density declined with and without sea otter presence and that the extent of the decline depends on the duration and magnitude of sea otter presence, with 100% decline in areas occupied by sea otters since 1994. Sea otter predation should be included in sea cucumber fishery management as a step toward ecosystem-based management.

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Diffusion modeling reveals effects of multiple release sites and human activity on a recolonizing apex predator

10.21203/rs.3.rs-341528/v1 ◽

2021 ◽

Author(s):

Joseph Eisaguirre ◽

Perry Williams ◽

Xinyi Lu ◽

Michelle Kissling ◽

William Beatty ◽

...

Keyword(s):

Human Activity ◽

Residence Time ◽

Prey Availability ◽

Commercial Fishing ◽

Apex Predators ◽

Sea Otters ◽

Southeast Alaska ◽

Bayesian Hierarchical ◽

Factors Influencing ◽

Multiple Population

Abstract Background: Reintroducing predators is a promising conservation tool to help remedy human-caused ecosystem changes. However, the growth and spread of a reintroduced population is a spatiotemporal process that is driven by a suite of factors, such as habitat change, human activity, and prey availability. Sea otters (Enhydra lutris) are apex predators of nearshore marine ecosystems that had declined nearly to extinction across much of their range by the early 20th century. In Southeast Alaska, which is comprised of a diverse matrix of nearshore habitat and managed areas, reintroduction of 413 individuals in the late 1960s initiated the growth and spread of a population that now exceeds 25,000. Methods: Periodic aerial surveys in the region provide a time series of spatially-explicit data to investigate factors influencing this successful and ongoing recovery. We integrated an ecological diffusion model that accounted for spatially-variable motility and density-dependent population growth, as well as multiple population epicenters, into a Bayesian hierarchical framework to help understand the factors influencing the success of this recovery. Results: Our results indicated that sea otters exhibited higher residence time as well as greater equilibrium abundance in Glacier Bay, a protected area, and in areas where there is limited or no commercial fishing. Asymptotic spread rates suggested sea otters colonized Southeast Alaska at rates of 1-8 km/yr with lower rates occurring in areas correlated with higher residence time, which primarily included areas near shore and closed to commercial fishing. Further, we found that the intrinsic growth rate of sea otters may be higher than previous estimates suggested. Conclusions: This study shows how predator recolonization can occur from multiple population epicenters. Additionally, our results suggest spatial heterogeneity in the physical environment as well as human activity and management can influence recolonization processes, both in terms of movement (or motility) and density dependence.

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Novel infections of Corynosoma enhydri and Profilicollis sp. (Acanthocephala: Polymorphidae) identified in sea otters Enhydra lutris

Diseases of Aquatic Organisms ◽

10.3354/dao03442 ◽

2020 ◽

Vol 137 (3) ◽

pp. 239-246 ◽

Cited By ~ 1

Author(s):

KM Shanebeck ◽

J Lakemeyer ◽

U Siebert ◽

K Lehnert

Keyword(s):

Enhydra Lutris ◽

Sea Otters

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Characterizing the impact of recovering sea otters on commercially important crabs in California estuaries

Marine Ecology Progress Series ◽

10.3354/meps13530 ◽

2020 ◽

Vol 655 ◽

pp. 123-137

Author(s):

TM Grimes ◽

MT Tinker ◽

BB Hughes ◽

KE Boyer ◽

L Needles ◽

...

Keyword(s):

Abiotic Factors ◽

Sea Otter ◽

Dungeness Crab ◽

Sea Otters ◽

Elkhorn Slough ◽

Enhydra Lutris Nereis ◽

Crab Abundance ◽

Population Sizes ◽

Commercially Important ◽

The Impact

Protective legislation and management have led to an increase in California’s sea otter Enhydra lutris nereis population. While sea otter recovery has been linked to ecosystem benefits, sea otter predation may negatively affect commercially valuable species. Understanding the potential influence of sea otters is of particular importance as their range expands into estuaries that function as nurseries for commercially valuable species like Dungeness crab Metacarcinus magister. We consider how sea otter predation has affected the abundance and size of juvenile Dungeness crab in Elkhorn Slough, California, USA, and analyzed cancrid crab abundance and size across 4 California estuaries with and without sea otters to understand how biotic and abiotic factors contribute to observed variation in crab size and abundance. We compared trends in southern sea otters relative to Dungeness crab landings in California to assess whether increasing sea otter abundance have negatively impacted landings. In Elkhorn Slough, juvenile Dungeness crab abundance and size have declined since 2012, coinciding with sea otter population growth. However, the impact of sea otters on juvenile Dungeness crab size was habitat-specific and only significant in unvegetated habitat. Across estuaries, we found that cancrid crab abundance and size were negatively associated with sea otter presence. While abiotic factors varied among estuaries, these factors explained little of the observed variation in crab abundance or size. Although we found evidence that sea otters can have localized effects on cancrid crab populations within estuaries, we found no evidence that southern sea otters, at recent population sizes, have negatively impacted Dungeness crab landings in California from 2000-2014.

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