Shellfish Fishery Conflicts and Perceptions of Sea Otters in California and Alaska

Carswell, Lilian; Speckman, Suzann G.; Gill, Verena A.

doi:10.1016/b978-0-12-801402-8.00012-3

Cited by 30 publications

(39 citation statements)

References 8 publications

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“…While hailed as a conservation success story, the return of sea otters exemplifies the challenge of a predator returning to its native range, which raises ecological, conservation, and management questions (Roman et al 2015, Silliman et al 2018. In particular, the recovery of sea otter populations resulted in conflicts with human interests for shellfish resources (Carswell et al 2015). In SEAK from 2009 to 2012, commercially important marine species represented 46% of sea otter diets, and sea otter expansion contributed to declines in shellfish available for commercial harvest (Larson et al 2013, Hoyt 2015.…”

Section: Introductionmentioning

confidence: 99%

“…In SEAK from 2009 to 2012, commercially important marine species represented 46% of sea otter diets, and sea otter expansion contributed to declines in shellfish available for commercial harvest (Larson et al 2013, Hoyt 2015. In response, legislation was introduced to the Alaska State Senate in 2013 that proposed a bounty for sea otters that would be given to Alaskan Native harvesters (Carswell et al 2015). However, its passage would have put the State of Alaska in direct conflict with the federal government who has the legal authority to implement the MMPA and manage sea otter harvest.…”

Section: Introductionmentioning

confidence: 99%

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Location‐specific factors influence patterns and effects of subsistence sea otter harvest in Southeast Alaska

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To better understand the spatial context of population dynamics of sea otters (Enhydra lutris) in Southeast Alaska (SEAK), we investigated the spatial and temporal patterns of subsistence sea otter harvest and assessed the effect of harvest on population growth. U.S. federal law permits subsistence harvest of sea otters and sale of clothing and handicrafts made by coastal Alaska Natives. Hunters are required to self‐report these harvests along with information on date, location, age class, and sex. Using harvest data collected from 1988 to 2015, we developed a spatially explicit, age‐structured, density‐dependent population simulation model to explore the potential impacts of harvest on sea otter population dynamics. We examined patterns of harvest and simulation model results at two spatial scales: the SEAK stock and three smaller subregions that vary in sea otter occupation time and carrying capacity: Sitka Sound, Keku Strait, and the Maurelle Islands. Annual sea otter harvest in SEAK increased from 55 animals in 1988 to a reported maximum of 1449 animals in 2013. Estimated mean annual harvest rate was 2.8% at the SEAK stock scale, but ranged from 0% to 39.3% across the three focal subregions described above. Across all subregions (n = 55), annual sea otter harvest rate was strongly influenced by time since recolonization, sea otter population density, and proximity to communities with sea otter hunters. The simulation model predicted population trends and per capita harvest rates similar to those estimated from aerial survey data, providing a reasonable approximation of population dynamics. Results of the simulation model suggested that current harvest levels can reduce population size at both the SEAK and subregional scales. Variation in harvest impacts was a function of subregion‐specific factors, including time since recolonization and population status with respect to carrying capacity. We found that subsistence harvest and its population effects were scale‐ and location‐dependent, indicating that higher spatial and temporal resolution of sea otter population and hunting data could help address emerging sea otter management and conservation concerns in this region.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Location‐specific factors influence patterns and effects of subsistence sea otter harvest in Southeast Alaska

et al. 2019

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“…Some of these changes are considered beneficial, such as increased productivity in kelp (e.g., Macrocystis pyrifera, Nereocystis leutkeana, Alaria fistulosa; Duggins et al 1989), the associated restoration of ecosystem function (Estes et al 2010, Estes 2015, and restoration of subsistence uses of sea otters by indigenous communities (Salomon et al 2015). The recovery of sea otters, however, also leads to conflict with humans over particular marine resources, most notably large marine invertebrates (Wild and Ames 1974, Garshelis and Garshelis 1984, Carswell et al 2015. In Southeast Alaska, sea otter recovery has resulted in conflicts with several commercial shellfisheries (Larson et al 2013, Hoyt 2015.…”

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confidence: 99%

Trends and Carrying Capacity of Sea Otters in Southeast Alaska

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Sea otter populations in Southeast Alaska, USA, have increased dramatically from just over 400 translocated animals in the late 1960s to >8,000 by 2003. The recovery of sea otters to ecosystems from which they had been absent has affected coastal food webs, including commercially important fisheries, and thus information on expected growth and equilibrium abundances can help inform resource management. We compile available survey data for Southeast Alaska and fit a Bayesian state‐space model to estimate past trends and current abundance. Our model improves upon previous analyses by partitioning and quantifying sources of estimation error, accounting for over‐dispersion of aerial count data, and providing realistic measurements of uncertainty around point estimates of abundance at multiple spatial scales. We also provide estimates of carrying capacity (K) for Southeast Alaska, at regional and sub‐regional scales, and analyze growth rates, current population status and expected future trends. At the regional scale, the population increased from 13,221 otters in 2003 to 25,584 otters in 2011. The average annual growth rate in southern Southeast Alaska (7.8%) was higher than northern Southeast Alaska (2.7%); however, growth varied at the sub‐regional scale and there was a negative relationship between growth rates and the number of years sea otters were present in an area. Local populations vary in terms of current densities and expected future growth; the mean estimated density at K was 4.2 ± 1.58 sea otters/km2 of habitat (i.e., the sub‐tidal benthos between 0 m and 40 m depth) and current densities correspond on average to 50% of projected equilibrium values (range = 1–97%) with the earliest‐colonized sub‐regions tending to be closer to K. Assuming a similar range of equilibrium densities for currently un‐occupied habitats, the projected value of K for all of Southeast Alaska is 74,650 sea otters. Future analyses can improve upon the precision of K estimates by employing more frequent surveys at index sites and incorporating environmental covariates into the process model to generate more accurate, location‐specific estimates of equilibrium density. © 2019 The Authors. The Journal of Wildlife Management Published by Wiley Periodicals, Inc.

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“…Because demand for sea otter artifacts is small, the number of animals killed yearly is modest but increasing [currently averaging more than 1,000 per year in Alaska (USFWS, Anchorage, AK, United States)]. Competition between recolonizing sea otters and human fisheries for invertebrates (e.g., clams, crabs, abalone), whose populations expanded in the sea otters' absence, has led to conflict in some parts of their range (Carswell et al, 2015). In Alaska, some lawmakers in the state government have suggested that sea otters be culled to reduce pressure on certain commercially exploited invertebrates, but this would require a change in the Marine Mammal Protection Act of 1972.…”

Section: Key Questions and Challenges For Future Research And Managementmentioning

confidence: 99%

“…The effects of sea otters on commercial, recreational, and subsistence shellfish fisheries (Estes and VanBlaricom, 1985;Wendell et al, 1986b;Wendell, 1994;Watson and Smith, 1996;Larson et al, 2013;Hoyt, 2015) due to competition for prey have been among the most highly visible and politically charged of sea otters' interactions with human activities (Carswell et al, 2015). The development of commercial and recreational shellfish fisheries was fueled by the high abundance of benthic invertebrates that developed during the absence of their natural predator, the sea otter.…”

Section: Top Down Effectsmentioning

confidence: 99%

Future Directions in Sea Otter Research and Management

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The conservation and management of sea otters has benefited from a dedicated research effort over the past 60 years enabling this species to recover from a few thousand in the early 20th century to about 150,000 today. Continued research to allow full, pre-exploitation recovery and restoration of nearshore ecosystems should focus on at least seven key challenges: (1) Defining sea otter populations at smaller spatial scales that reflect this species' life history and dispersal patterns; (2) Understanding factors that regulate sea otter population density with a focus on index sites that are representative of the variety of littoral habitats occupied by sea otters around the North Pacific Rim;(3) Quantifying the effects of sea otters on the littoral community with a focus on how food availability limits population and ecosystem recovery and on predicting the effect of sea otter reoccupation on commercially valuable invertebrates; (4) Making sea otter monitoring programs comparable across geo-political boundaries through international collaboration to optimize survey efforts both spatially and temporally and to determine the cause of changes in sea otter demographics; (5) Evaluating the conservation benefits of sea otter reintroductions into historical habitat; (6) Assessing the socioeconomic costs and benefits of sea otter range expansion to anticipate and mitigate conflicts; (7) Recognizing in conservation and management plans that sea otters can be significantly affected by higher level predators in some circumstances. Many of these challenges will require new tools including the next generation geolocation tag technology that will allow assessments of long-range movements, dispersal and gene flow in various populations.

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Shellfish Fishery Conflicts and Perceptions of Sea Otters in California and Alaska

Cited by 30 publications

References 8 publications

Location‐specific factors influence patterns and effects of subsistence sea otter harvest in Southeast Alaska

Location‐specific factors influence patterns and effects of subsistence sea otter harvest in Southeast Alaska

Trends and Carrying Capacity of Sea Otters in Southeast Alaska

Future Directions in Sea Otter Research and Management

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