Geoduck Clam (Panopea Abrupta) Demographics and Mortality Rates in
the Presence of Sea Otters (Enhydra Lutris) and Commercial Harvesting

Reidy, Rhonda; Cox, Sean P.

doi:10.2174/1874401x01306010028

Cited by 8 publications

(2 citation statements)

References 28 publications

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“…In the temporary absence of sea otters after their extirpation from portions of their range, high‐value invertebrate fisheries that target many of the same calorically rich prey preferred by sea otters developed. The recolonization and reintroduction of sea otters to areas of historical sea otter occupation, that now co‐occur spatially with fisheries, has led to conflicts between sea otters and fisheries along the North American Pacific Coast ( e.g., Estes and VanBlaricom , Reidy , USFWS , Larson et al . , Honka , Hoyt ), and in some cases has had measurable impacts on fisheries species (Fanshawe et al .…”

Section: Discussionmentioning

confidence: 99%

Influence of occupation history and habitat on Washington sea otter diet

Hale

Laidre

Tinker

et al. 2019

Marine Mammal Science

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Habitat characteristics are primary determinants of nearshore marine communities. However, biological drivers like predation can also be important for community composition. Sea otters (Enhydra lutris ssp.) are a salient example of a keystone species exerting top‐down control on ecosystem community structure. The translocation and subsequent population growth and range expansion of the northern sea otter (Enhydra lutris kenyoni) in Washington State over the last five decades has created a spatio‐temporal gradient in sea otter occupation time and density, and acts as a natural experiment to quantify how sea otter population status and habitat type influence sea otter diet. We collected focal observations of sea otters foraging at sites across the gradient in varying habitat types between 2010 and 2017. We quantified sea otter diet composition and diversity, and long‐term rates of energy gain across the gradient. We found that sea otter diet diversity was positively correlated with cumulative sea otter density, while rate of energy gain was negatively correlated with cumulative density. Additionally, we found that habitat type explained 1.77 times more variance in sea otter diet composition than sea otter cumulative density. Long‐term diet studies can provide a broader picture of sea otter population status in Washington State.

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Section: Discussionmentioning

confidence: 99%

Influence of occupation history and habitat on Washington sea otter diet

Hale

Laidre

Tinker

et al. 2019

Marine Mammal Science

View full text Add to dashboard Cite

show abstract

“…However, there is a delay between the time when sea otters expand into an area and when commercial-scale harvesting of shellfish becomes inviable, the length of which is somewhat species-dependent. Sea urchins and abalone are depleted quickly because they are highly accessible and relatively immobile, whereas geoducks-a species of bivalve that burrows deeply in soft sediment and can occur in deep water-are depleted at a slower rate Kvitek et al, 1993;Watson and Smith, 1996;Reidy and Cox, 2013;Hoyt, 2015).…”

Section: Top Down Effectsmentioning

confidence: 99%

Future Directions in Sea Otter Research and Management

et al. 2019

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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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The interaction of intraspecific competition and habitat on individual diet specialization: a near range-wide examination of sea otters

et al. 2015

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The quantification of individuality is a common research theme in the fields of population, community, and evolutionary ecology. The potential for individuality to arise is likely context-dependent, and the influence of habitat characteristics on its prevalence has received less attention than intraspecific competition. We examined individual diet specialization in 16 sea otter (Enhydra lutris) populations from southern California to the Aleutian Islands in Alaska. Because population histories, relative densities, and habitat characteristics vary widely among sites, we could examine the effects of intraspecific competition and habitat on the prevalence of individual diet specialization. Using observed diet data, we classified half of our sites as rocky substrate habitats and the other half containing a mixture of rocky and unconsolidated (soft) sediment substrates. We used stable isotope data to quantify population- and individual-level diet variation. Among rocky substrate sites, the slope [±standard error (SE)] of the positive significant relationship between the within-individual component (WIC) and total isotopic niche width (TINW) was shallow (0.23 ± 0.07) and negatively correlated with sea otter density. In contrast, the slope of the positive WIC/TINW relationship for populations inhabiting mixed substrate habitats was much higher (0.53 ± 0.14), suggesting a low degree of individuality, irrespective of intraspecific competition. Our results show that the potential for individuality to occur as a result of increasing intraspecific competition is context-dependent and that habitat characteristics, which ultimately influence prey diversity, relative abundance, and the range of skillsets required for efficient prey procurement, are important in determining when and where individual diet specialization occurs in nature.

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Geoduck Clam (Panopea Abrupta) Demographics and Mortality Rates in the Presence of Sea Otters (Enhydra Lutris) and Commercial Harvesting

Cited by 8 publications

References 28 publications

Influence of occupation history and habitat on Washington sea otter diet

Influence of occupation history and habitat on Washington sea otter diet

Future Directions in Sea Otter Research and Management

The interaction of intraspecific competition and habitat on individual diet specialization: a near range-wide examination of sea otters

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