Sea Otter Diets in a Declining Population in Alaska

Green, Gregory A.; Brueggeman, John J.

doi:10.1111/j.1748-7692.1991.tb00114.x

Cited by 7 publications

(4 citation statements)

References 11 publications

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“…Southern sea otters and northern sea otters consume a greater quantity of hard, benthic prey [ 32 , 84 – 91 ], which require a greater bite force than is required for fish. Russian and northern sea otters inhabiting parts of southwest Alaska including Alaska Peninsula, Aleutian Islands, and Amchitka Island include epibenthic fish such as flatfish (Pleuronectids) in their diet [ 28 , 85 , 92 ]. However, populations in Southwest Alaska still incorporate more benthic invertebrates than fish into their diets [ 85 , 92 ].…”

Section: Discussionmentioning

confidence: 99%

“…Russian and northern sea otters inhabiting parts of southwest Alaska including Alaska Peninsula, Aleutian Islands, and Amchitka Island include epibenthic fish such as flatfish (Pleuronectids) in their diet [ 28 , 85 , 92 ]. However, populations in Southwest Alaska still incorporate more benthic invertebrates than fish into their diets [ 85 , 92 ]. Russian sea otters, on the other hand, incorporate a larger proportion of fish in their diets [ 28 ], which may correspond with smaller MA masseter and estimated bite forces compared to southern and northern sea otters.…”

Section: Discussionmentioning

confidence: 99%

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Divergent Skull Morphology Supports Two Trophic Specializations in Otters (Lutrinae)

2015

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Variation in terrestrial mammalian skull morphology is known to constrain feeding performance, which in turn influences dietary habits and ultimately fitness. Among mustelids, otters have evolved two feeding specializations: underwater raptorial capture of prey (mouth-oriented) and capture of prey by hand (hand-oriented), both of which have likely associations with morphology and bite performance. However, feeding biomechanics and performance data for otters are sparse. The first goal of this study was to investigate the relationships between feeding morphology and bite performance among two mouth-oriented piscivores (Pteronura brasiliensis and Lontra canadensis) and two hand-oriented invertebrate specialists (Enhydra lutris and Aonyx cinerea). Since other vertebrate taxa that are mouth-oriented piscivores tend to possess longer skulls and mandibles, with jaws designed for increased velocity at the expense of biting capability, we hypothesized that mouth-oriented otters would also possess long, narrow skulls indicative of high velocity jaws. Conversely, hand-oriented otters were expected to possess short, blunt skulls with adaptations to increase bite force and crushing capability. Concomitant with these skull shapes we hypothesized that sea otters would possess a greater mandibular bluntness index, providing for a greater mechanical advantage compared to other otter species investigated. A second goal was to examine morphological variation at a finer scale by assessing variation in cranial morphology among three sea otter subspecies. Since diet varies among these subspecies, and their populations are isolated, we hypothesized that the magnitude of mandibular bluntness and concomitant mechanical advantage, as well as occlusal surface area would also vary within species according to their primary food source (fish versus hard invertebrates). Functional expectations were met for comparisons among and within species. Among species the phylogeny suggests a deeply rooted transition to alternative foraging types. Yet within foraging types alternative species were also strongly variable, suggesting either selective differences in the extent or nature of realized foraging mode, or an accumulation of non-adaptive changes during the long independent evolutionary history. At the finest scale, variation among subspecies indicates that trophic adaptation occurred rapidly, making it interesting that we happened to find both deeply and shallowly-rooted transformations associated with diet type in otter species and subspecies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Divergent Skull Morphology Supports Two Trophic Specializations in Otters (Lutrinae)

2015

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“…Modern observations of sea otter diet show they preferentially consume benthic invertebrates, particularly sea urchins, abalones, clams, mussels, crabs and snails (Breen et al, 1982;Estes, 1990;Green and Brueggeman, 1991;Hines and Pearse, 1982;Oliver, 1988, 1992;Ostfeld, 1982). In some areas, fish are also important prey items (Estes, 1990;Watt et al, 2000), although this behavior is less common.…”

Section: Introductionmentioning

confidence: 97%

Historical ecology of late Holocene sea otters (Enhydra lutris) from northern British Columbia: isotopic and zooarchaeological perspectives

Szpak¹,

Orchard²,

McKechnie³

et al. 2012

Journal of Archaeological Science

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“…Estudos detalhados a respeito dos hábitos alimentares, principalmente de lontras-marinhas, são realizados, em sua maioria, a partir da análise de conteúdo fecal de animais vivos (Faurot et al 1986, Green & Brueggeman 1991, Medina-Vogel et al 2004, Mangel et al 2010. Primeiramente, as fezes são lavadas e secas para posterior triagem.…”

Section: Conteúdo Do Trato Gastrointestinalunclassified

Ecologia Alimentar Em Mamíferos Marinhos: Técnicas De Estudo

2012

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Os mamíferos marinhos predam sobre uma grande variedade de presas de diferentes níveis tróficos, ocupando nichos diferenciados tanto em cadeias tróficas curtas como em cadeias tróficas longas. Estudos a respeito da ecologia alimentar dos mamíferos marinhos são importantes para entender suas interações tróficas, além de identificar as posições que eles ocupam nas teias alimentares. Estes estudos contribuem para um melhor entendimento da estrutura trófica, do fluxo de energia e do funcionamento dos ecossistemas marinhos. O objetivo dessa revisão foi apresentar os principais métodos utilizados nos estudos de ecologia trófica de mamíferos marinhos, incluindo os requisitos para suas aplicações, as informações que podem ser geradas, assim como as suas limitações. O método mais tradicional, e também o mais antigo, é a análise do conteúdo estomacal e das fezes. A importância dessa ferramenta está na possibilidade de identificação das presas e de se estimar a sua biomassa. Estas características também a tornam uma ferramenta útil como base para a aplicação dos demais métodos. Mais recentemente, duas técnicas que envolvem mensurações de isótopos estáveis e de ácidos graxos têm sido aplicadas. Ambas se baseiam no princípio de que as razões isotópicas e as assinaturas de ácidos graxos do predador refletem aquelas das presas de maneira previsível, possibilitando investigações em escala temporal e espacial do forrageamento dos mamíferos marinhos. Entretanto, essas técnicas apresentam limitações pelo fato de não permitirem a identificação das espécies consumidas, e pela necessidade de conhecimento prévio sobre as assinaturas de ácidos graxos ou razões isotópicas das presas. O fato é que nenhum dos três métodos responde a todas as perguntas em relação ao estudo da ecologia alimentar e das relações tróficas dos mamíferos marinhos. Eles constituem ferramentas complementares que devem ser usadas simultaneamente sempre que possível. Além disso, a determinação das concentrações e dos perfis de contaminação por micropoluentes pode trazer informações adicionais sobre a dieta e hábitos alimentares de mamíferos marinhos. Palavras-chave: dieta; relações tróficas; conteúdo estomacal; isótopos estáveis; ácidos graxos. ABSTRACT FEEDING ECOLOGY OF MARINE MAMMALS: METHODS OF STUDY. Marine mammals feed on a wide variety of preys from distinct trophic levels, occupying different niches in short and in long food chains. Studies on feeding ecology of marine mammals are important to understand their trophic relationships, as well as assessing their trophic levels in a food web. These investigations contribute for a better comprehension of trophic structure, energy flow and function of the marine ecosystems. The goal of this review is to present the main methods used in studies of trophic ecology of marine mammals, including requirements to their applications, information that can be generated, as well as their limitations. The more conventional method, also the older one, is the analysis of stomach contents and feces. The importance of this tool is...

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Sea Otter Diets in a Declining Population in Alaska

Cited by 7 publications

References 11 publications

Divergent Skull Morphology Supports Two Trophic Specializations in Otters (Lutrinae)

Divergent Skull Morphology Supports Two Trophic Specializations in Otters (Lutrinae)

Historical ecology of late Holocene sea otters (Enhydra lutris) from northern British Columbia: isotopic and zooarchaeological perspectives

Ecologia Alimentar Em Mamíferos Marinhos: Técnicas De Estudo

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