Prey Selection by Marine-Coastal River Otters (<i>Lontra canadensis</i>) in Newfoundland, Canada

Côté, David; Stewart, H. M.; Gregory, Robert S.; Gosse, John W.; Reynolds, John; Stenson, Garry B.; Miller, E. H.

doi:10.1644/07-mamm-a-192.1

Cited by 23 publications

(12 citation statements)

References 47 publications

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“…However, several other dietary studies have also found a large number of bullheads in otter diet (see Copp and Roche 2003), with some noting preferential selection (Almeida et al 2012). Cote et al (2008) also found a preference for slow-swimming marine cottids in North American river otters. In contrast, Britton et al (2006) reported bullheads and cyprinids to be of equal importance and present in otter diet in similar amounts throughout the year.…”

Section: Evidence For Prey Selection By Ottersmentioning

confidence: 94%

Fish selection by riverine Eurasian otters in lowland England

Grant

Harrington

2015

Mamm Res

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Eurasian otters (Lutra lutra) may conflict with humans using fish stocks for food, income or recreation. Understanding fish selection by otters is important for predicting and managing potential conflicts. We used spraint analysis to describe the diet of Eurasian otters on rivers in the Upper Thames Valley, lowland England, in summer and winter, focusing specifically on the species and size of fish consumed. We assessed the proportion of fish consumed that were of potential commercial or sporting value (the 'Potential Value' category). Within this group, we assessed relative selection for family and length by comparing fish found in otter diet with their local availability. Local availability was estimated from UK Environment Agency electrofishing survey data. Fish represented 46 % (relative frequency of occurrence, RFO) of total otter diet, with fish of Potential Value representing 19 % (RFO). In the Potential Value category, cyprinids were relatively avoided; percids and esocids were relatively preferred. Most (∼80 %) fish prey items originated from fish 4-13 cm in length, 3 % from fish>20 cm. Smaller (0-10 cm) percids and cyprinids, and larger (16-20 cm) esocids, were preferred. In summer, diet was broad, comprising 31 % (RFO) fish, 24 % birds and 14 % crayfish. In winter, diet was predominantly fish (68 % RFO) with crayfish and birds accounting for ∼5 % each. In summer, most fish consumed (70 % RFO) were the relatively slow-swimming common bullhead (Cottus gobio). Significantly more of the fasterswimming cyprinids were consumed in winter, presumably because they are easier to catch when the water is colder.

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Section: Evidence For Prey Selection By Ottersmentioning

confidence: 94%

Fish selection by riverine Eurasian otters in lowland England

Grant

Harrington

2015

Mamm Res

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“…Therefore, if the diet of otters fails to fluctuate according to prey availability, then it is likely that they are selectively foraging. Otter diet does, however, often tend toward seasonal fluctuation (although not always; see Cote et al 2008), most notably in relative proportions of fish and crayfish from summer to winter (Tumlison and Karnes 1987;Miller 1992;Noordhuis 2002;Roberts et al 2008). At a finer taxonomic scale, seasonal differences in occurrence of fish families in otter diet are also common (Greer 1955;Sheldon and Toll 1964;Anderson and Woolf 1987;McDonald 1989;Reid et al 1994;Cogliano 2003;Roberts 2003;Roberts et al 2008;Wengeler et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Seasonal diet of the northern river otter (Lontra canadensis): what drives prey selection?

2015

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Diet of the northern river otter (Lontra canadensis (Schreber, 1777)) has been examined throughout much of its range and across many habitat types. Few studies have examined prey selection based on prey abundance estimates, however, and prey selection results have been inconsistent. We determined composition, seasonal variation, and prey selection of otter diet in northern Utah comprising multiple habitat types and prey communities. We evaluated the hypothesis that otters take prey according to availability and in inverse proportion to swimming ability. Fish was the primary class of prey taken by otters (96.5%), followed by crustaceans (16.9%). Among families, otter diet was composed primarily of Salmonidae and Cottidae, the two families that dominated the fish community of the main-channel habitat. Otter diet varied seasonally for nearly all classes (G [24] = 127.8, P < 0.001) and families (G [18] = 132.94, P < 0.001) of prey. In particular, fish occurrence was lower during summer than during other seasons (P ≤ 0.05), whereas crustacean (i.e., crayfish (Astacoidea)) occurrence was higher (G [3] = 71.1, P < 0.001). At the family level, occurrence of Salmonidae was greatest during fall (G [3] = 11.7, P < 0.01). Within one of our habitat types, we found otters to select for prey in proportion to abundance and in inverse proportion to swimming ability, with otters selecting for Catostomidae and Cyprinidae, against Salmonidae, and Cottidae according to its abundance. We conclude that habitat type may be the initial driver of prey selection, while factors such as abundance, agility, and life history of prey may be secondary drivers.Résumé : Le régime alimentaire de la loutre de rivière (Lontra canadensis (Schreber, 1777)) a été étudié dans la majeure partie de son aire de répartition et dans de nombreux types d'habitats. Peu d'études se sont toutefois penchées sur la sélection de proies à la lumière d'estimations de l'abondance des proies, et les résultats touchant à la sélection de proies se sont avérés peu cohérents. Nous avons déterminé la composition, les variations saisonnières et la sélection de proies de l'alimentation de la loutre dans le nord de l'Utah, une région qui comprend de nombreux types d'habitats et communautés de proies. Nous avons évalué l'hypothèse voulant que les loutres choisissent leurs proies selon leur disponibilité et de manière inversement proportionnelle à leur capacité natatoire. Les poissons constituaient la principale classe de proies prises par les loutres (96,5 %), suivis des crustacés (16,9 %). En ce qui concerne les familles, le régime des loutres était principalement composé de salmonidés et de cottidés, les deux familles dominantes de la communauté de poissons de l'habitat de chenal principal. Le régime alimentaire des loutres variait selon la saison pour presque toutes les classes (G [24] = 127,8, P < 0,001) et familles (G [18] = 132,94, P < 0,001) de proies. En particulier, la présence de poissons était plus faible durant l'été que durant d'autres saisons (P ≤ 0,05), alors que ...

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“…While otters consume a large number of species, they feed mostly on fish and shellfish (90% of their diet), and less so on other invertebrates, amphibians, birds, and mammals (Anderson‐Bledsoe and Scanlon ; Carss ; Cote et al ; Evans et al ; Fretueg et al ; Kean et al ; Mason et al ; Reid et al ). This is of prominent conservation concern because the position of river otters at the top of the food chain increases their susceptibility to bioaccumulation of a wide‐range of contaminants (Anderson‐Bledsoe and Scanlon ; Evans et al ; Kean et al ; Mason et al ).…”

Section: Exposure To Anthropogenic Pollutantsmentioning

confidence: 99%

Impacts of Pollutants on Beavers and Otters with Implications for Ecosystem Ramifications

Peterson

Schulte

2016

Contemporary Water Research

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Anthropogenic pollution has impacted ecosystems and organisms globally. Aquatic freshwater systems are of particular concern because of their importance to human health and livelihoods. Sentinel species can serve as indicators for both individual and population‐level health risks to both wildlife and humans, and therefore facilitate the mitigation and prevention of such contamination. When such species are also keystone species and/or ecological engineers in aquatic ecosystems, understanding the influence of pollutants on their physiology and behavior acquires added importance. Given that river otters (Lontra canadensis and Lutra lutra) and beavers (Castor canadensis and C. fiber) serve such roles and are susceptible to a wide‐range of anthropogenic pollution, this makes them prime candidates as indicators or sentinels of aquatic ecosystem health. We review published evidence on the toxicological impacts of pollutants in beavers and river otters and discuss the implications of exposure to their behavioral systems, conservation, and surrounding ecosystem.

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Prey Selection by Marine-Coastal River Otters (Lontra canadensis) in Newfoundland, Canada

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 23 publications

References 47 publications

Fish selection by riverine Eurasian otters in lowland England

Fish selection by riverine Eurasian otters in lowland England

Seasonal diet of the northern river otter (Lontra canadensis): what drives prey selection?

Impacts of Pollutants on Beavers and Otters with Implications for Ecosystem Ramifications

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