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

2013 ◽  
Vol 70 (10) ◽  
pp. 1498-1507 ◽  
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.

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

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.

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

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.

scholarly journals The historical and contemporary status of the sea otter Enhydra lutris population on Urup Island, southern Kuril Islands

Oryx ◽  
2021 ◽  
pp. 1-6
Author(s):  
Igor Popov ◽  
Alexey Scopin
Keyword(s):  
Total Population ◽  
Kuril Islands ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
The Past ◽  
Remote Island ◽  
Contemporary Status ◽  
Wildlife Refuges ◽  
Effective Conservation

Abstract We describe the population of the Еndangered sea otter Enhydra lutris on Urup Island, one of the main wildlife refuges in the southern Kuril Islands of Russia. We reviewed historical and local reports of the sea otter, identified its habitat around the island, and surveyed the coastal waters of the island in 2019. Sea otters were numerous on Urup Island in the past but were hunted excessively and almost exterminated by the 1950s. Since then, sea otter populations have increased, and as the island is almost uninhabited we expected otters to be numerous. This was not the case, and we estimated the total population to be 363 ± SE 126 individuals. Our observation of two skinned carcasses on the shore suggests the low numbers are a result of poaching for the illegal fur trade. The case of Urup Island demonstrates that sea otters require active conservation, as even on a remote island they remain threatened. Establishment of protected areas would be an effective conservation measure for this species, although the suppression of demand for sea otter fur is of the greatest importance.

scholarly journals Predators, Disease, and Environmental Change in the Nearshore Ecosystem: Mortality in Southern Sea Otters (Enhydra lutris nereis) From 1998–2012

2020 ◽  
Vol 7 ◽  
Author(s):  
Melissa A. Miller ◽  
Megan E. Moriarty ◽  
Laird Henkel ◽  
Martin Tim Tinker ◽  
Tristan L. Burgess ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Population Level ◽  
Large Sample Size ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Sarcocystis Neurona ◽  
Enhydra Lutris Nereis ◽  
Protozoal Infection ◽  
Demographic Attributes

We compiled findings from 15 years (1998–2012) of southern sea otter (Enhydra lutris nereis) necropsies, incorporating data from 560 animals. Sensitive diagnostic tests were used to detect biotoxins, bacteria, parasites and fungi. Methods to classify primary and contributing causes of death (COD) and sequelae utilized an updated understanding of health risks affecting this population. Several interesting patterns emerged, including identification of coastal regions of high mortality risk for sea otter mortality due to shark bite, cardiomyopathy, toxoplasmosis, sarcocystosis, acanthocephalan peritonitis and coccidioidomycosis. We identified demographic attributes that enhanced the risk of disease in relation to age, sex, and reproductive stage. Death due to white shark (Carcharodon carcharias) bite increased dramatically during the study period and was the most common primary COD. However, when primary and contributing COD were combined, the most prevalent COD was infectious disease (affecting 63% of otters), especially fatal infections by acanthocephalans (Profilicollis spp.) and protozoa (e.g., Sarcocystis neurona and Toxoplasma gondii). Fatal bacterial infections were also extremely common as a primary process or a sequela, affecting 68% of examined otters. Substantial advances were made in identifying sea otters that died following exposure to the pervasive marine neurotoxin domoic acid (DA), and DA intoxication was conservatively estimated as a primary or contributing COD for 20% of otters. Cardiomyopathy was also highly prevalent as a primary or contributing COD (41%) and exhibited significant associations with DA intoxication and protozoal infection. For adult and aged adult females in late pup care through post-weaning at the time of death, 83% had end lactation syndrome (ELS) as a primary or contributing COD. This comprehensive longitudinal dataset is unique in its depth and scope. The large sample size and extensive time period provided an opportunity to investigate mortality patterns in a changing environment and identify spatial and temporal disease “hot spots” and emerging threats. Our findings will help improve estimates of population-level impacts of specific threats and optimize conservation and environmental mitigation efforts for this threatened species.

scholarly journals Archaeological mitogenomes illuminate the historical ecology of sea otters ( Enhydra lutris ) and the viability of reintroduction

2020 ◽  
Vol 287 (1940) ◽  
pp. 20202343
Author(s):  
Hannah P. Wellman ◽  
Rita M. Austin ◽  
Nihan D. Dagtas ◽  
Madonna L. Moss ◽  
Torben C. Rick ◽  
...  
Keyword(s):  
British Columbia ◽  
Ancient Dna ◽  
Historical Ecology ◽  
Mitochondrial Genomes ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Dental Calculus ◽  
Sea Otters ◽  
Dna Analyses ◽  
Modern Context

Genetic analyses are an important contribution to wildlife reintroductions, particularly in the modern context of extirpations and ecological destruction. To address the complex historical ecology of the sea otter ( Enhydra lutris ) and its failed 1970s reintroduction to coastal Oregon, we compared mitochondrial genomes of pre-extirpation Oregon sea otters to extant and historical populations across the range. We sequenced, to our knowledge, the first complete ancient mitogenomes from archaeological Oregon sea otter dentine and historical sea otter dental calculus. Archaeological Oregon sea otters ( n = 20) represent 10 haplotypes, which cluster with haplotypes from Alaska, Washington and British Columbia, and exhibit a clear division from California haplotypes. Our results suggest that extant northern populations are appropriate for future reintroduction efforts. This project demonstrates the feasibility of mitogenome capture and sequencing from non-human dental calculus and the diverse applications of ancient DNA analyses to pressing ecological and conservation topics and the management of at-risk/extirpated species.

Primary intracranial fibrosarcoma in a southern sea otter Enhydra lutris nereis

2020 ◽  
Vol 138 ◽  
pp. 207-213
Author(s):  
AR Armwood ◽  
CE Anderson ◽  
T Clauss ◽  
AC Camus
Keyword(s):  
Smooth Muscle Actin ◽  
Brain Lesion ◽  
Acute Onset ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Mammal Species ◽  
Sea Otters ◽  
Enhydra Lutris Nereis ◽  
High Mitotic Count ◽  
Southern Sea Otter

Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. An 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. Magnetic resonance imaging of the head revealed a large, central brain lesion. After no improvement with treatment, euthanasia was elected due to a poor prognosis. Grossly, a poorly demarcated, granular, tan mass expanded the cranial meninges in the longitudinal fissure at the level of the cruciate sulcus and extended into the underlying gray matter and superficial white matter. Histologically, the mass was composed of spindle cells, forming haphazardly arranged interlacing bundles and herringbone patterns, with a high mitotic count, moderate cellular pleomorphism, and prominent vascularization. Neoplastic cells demonstrated positive immunoreactivity for vimentin and negative immunoreactivity for smooth muscle actin, factor VIII-related antigen, S100, melan-A, E-cadherin, desmin, glial fibrillary acidic protein, and cytokeratin AE1/AE3. Based on gross, histologic, and immunohistochemical findings, the mass was most consistent with a primary intracranial fibrosarcoma (PIF). PIFs are a rare neoplasm in both humans and other animals with few reports in the veterinary literature. This is the first recorded case of a PIF in a sea otter.

scholarly journals Harlequin Ducks (Histrionicus histrionicus) Scavenge Sea Urchin Fragments from Foraging Sea Otters (Enhydra lutris)

2016 ◽  
Vol 130 (2) ◽  
pp. 91 ◽  
Author(s):  
Erin Rechsteiner ◽  
Angeleen Olson
Keyword(s):  
Red Sea ◽  
Sea Urchins ◽  
Keystone Species ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Important Prey ◽  
Histrionicus Histrionicus ◽  
Harlequin Ducks

Foraging animals may risk association with potential predators to obtain otherwise inaccessible prey. We observed this strategy in wintering Harlequin Ducks (Histrionicus histrionicus) scavenging fragments of Red Sea Urchins (Mesocentrotus franciscanus) from foraging Sea Otters (Enhydra lutris) that were re-occupying an area from which they had been ecologically absent since about 1850. Harlequin Ducks, like other sea ducks, have not previously been reported scavenging from other birds or mammals. In British columbia, Red Sea Urchins have reached large sizes and densities since the removal of Sea Otter predators by the marine fur trade in the 18th and 19th centuries. Observations of Sea Otters and Harlequin Ducks were made in 4 areas, spanning a time gradient of Sea Otter occupation from 1 to 5 years. During 3 months of observations (December 2013 – February 2014), Harlequin Ducks were associated with foraging Sea Otters only at sites that were recently occupied by Sea Otters (≤ 2 months), where the proportion of urchins in Sea Otter diets was highest and where the ducks acquired urchin fragments from foraging Sea Otters. We suggest that Sea Otters re-occupying their historic range and consuming predominantly large Red Sea Urchins provide a temporarily available prey subsidy for Harlequin Ducks. Our observations document a novel effect of Sea Otters providing important prey supplementation to a marine bird when foraging in urchin-rich habitats, contributing to the overall role of Sea Otters as a keystone species.

scholarly journals Predation of Juvenile Japanese Sea Cucumber Apostichopus japonicus by Kelp Crab Pugettia ferox

2021 ◽  
Vol 8 ◽  
Author(s):  
Nobuharu Inaba ◽  
Takuma Matsumoto ◽  
Hiroshi Kawai ◽  
Yuji Anaguchi ◽  
Kohei Matsuno
Keyword(s):  
High Mortality ◽  
Sea Cucumber ◽  
Laboratory Experiments ◽  
Apostichopus Japonicus ◽  
Life Stage ◽  
Early Life Stage ◽  
Food Storage ◽  
Sea Cucumbers ◽  
Commercially Important ◽  
Japanese Sea Cucumber

The predation of commercially important Japanese sea cucumber Apostichopus japonicus by the kelp crab Pugettia ferox, widely distributed in coastal northeast Asia, was examined in field sampling and laboratory experiments. The ossicles of A. japonicus were detected from the stomach contents of a natural population of P. ferox at the rate of 32.4% of 68 individuals collected within artificial intermediate sea cucumber reefs for releasing hatchery-produced juveniles in December 2018. In the following laboratory experiments, a high mortality rate (7.7 ± 2.4 individuals day–1) of juvenile A. japonicus (15.35 ± 2.47 mm) was observed despite the different sizes and sex of P. ferox tested. It was also confirmed that a maximum of five sea cucumbers was killed and cut into small pieces within the first 2 h. Smaller and younger P. ferox individuals (adolescent) between carapace widths of 14.2–17.8 mm actively decorated themselves using pieces of chopped sea cucumber after feeding. Attached pieces of sea cucumber were observed to be fully eaten within a week, suggesting a possible strategy by P. ferox of short-term food storage as well as mimicry. This study demonstrates considerable evidence that predation mortality by sufficiently mobile P. ferox on commercially important A. japonicus can be significant, causing high mortality at the early life stage in the natural environment, especially in areas releasing hatchery-produced juveniles. It is also worth noting that the utilization of freshly chopped sea cucumbers as decoration material and food storage is a unique and novel ecological trait of P. ferox.

scholarly journals Sea Otter, Enhydra lutris, Sightings off Haida Gwaii / Queen Charlotte Islands, British Columbia, 1972-2002

2004 ◽  
Vol 118 (2) ◽  
pp. 270
Author(s):  
Kimberly Raum-Suryan ◽  
Kenneth Pitcher ◽  
Richard Lamy
Keyword(s):  
British Columbia ◽  
Steller Sea Lion ◽  
Sea Otter ◽  
Eumetopias Jubatus ◽  
Enhydra Lutris ◽  
Haida Gwaii ◽  
Sea Lion ◽  
Sea Otters ◽  
The Past ◽  
Queen Charlotte Islands

On 27 June 2001 we observed and photographed a Sea Otter (Enhydra lutris) adjacent to a Steller Sea Lion (Eumetopias jubatus) haulout near Sgang Gwaay (Anthony Island), Haida Gwaii / Queen Charlotte Islands. This is one of only eight documented sightings of Sea Otters in these waters during the past 30 years. These sightings may represent the beginning of the expansion of Sea Otters to their former range off Haida Gwaii.

scholarly journals Use of the ACTH challenge test to identify the predominant glucocorticoid in the southern sea otter (Enhydra lutris nereis)

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
M J Murray ◽  
M A Young ◽  
R M Santymire
Keyword(s):  
Challenge Test ◽  
Controlled Study ◽  
Sea Otter ◽  
Saline Injection ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Late 20Th Century ◽  
Acth Challenge ◽  
Human Care ◽  
The Individual

Abstract After nearly being hunted to extinction during the fur trade of the late 20th Century, sea otter (Enhydra lutris) populations have recovered to varying degrees of their historical range. While overall population numbers and range have increased, there are regions in which expansion has occurred at a slower rate and/or animal numbers have decreased, which may be a result of chronic stress from a variety of sources. Some have employed glucocorticoid analysis in their attempts to validate these explanations. Our goal was to conduct a controlled study using sea otters managed under human care to validate the use of serum glucocorticoid analysis to monitor stress physiology in the sea otter. We used a standard ACTH challenge test to compare cortisol and corticosterone responses, thereby identifying the primary glucocorticoid in the sea otter. Fourteen sea otters of both sexes (five males, nine females), including juveniles, sub-adults and adults, participated in the study. The results of the testing supported cortisol as the primary glucocorticoid in the sea otter. Sex and age did not affect how the individual responded to the ACTH or saline injection. Interestingly, the saline injection not only confirmed the effects of the ACTH on glucocorticoid release from the adrenal glands but also provided information on how long it takes the sea otter’s glucocorticoid levels to return to baseline after capture and sedation. The insight gained from this study will aid in future efforts to better understand the role of stress in free-ranging sea otter populations. Recognition of the primary glucocorticoid will facilitate evaluation of more stable biological material, such as fur or whiskers, which tend to be less affected by the diurnal cycling of glucocorticoids.

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