River Otter (Lontra canadensis) Food Habits in a Washington Coast Watershed: Implications for a Threatened Species

A DNA‐based evaluation of North American river otter diet with respect to fishes: Implications for the conservation of aquatic predators and their prey

“…This includes data on seine and electrofishing surveys for fish, harvest data representing anglers' creel catch returns and numbers of otters trapped. Indiana residents generally have a favourable opinion about otters (Glas & Prokopy, 2016), but anglers often express concerns about the impact on fish assemblages, particularly the effect of predation on fish stocks and the threat to management efforts such as species reintroductions (Scordino et al, 2016) The purpose of this study was to determine whether a DNAbased approach to characterizing diet is technically feasible and biologically informative with respect to otters and fish species in Indiana. The primary objectives were (i) to determine whether DNA from prey items recovered from otter stomachs could be used to identify the species consumed and (ii) to quantify the relative proportions of fish prey species involved.…”

“…This includes data on seine and electrofishing surveys for fish, harvest data representing anglers' creel catch returns and numbers of otters trapped. Indiana residents generally have a favourable opinion about otters (Glas & Prokopy, 2016), but anglers often express concerns about the impact on fish assemblages, particularly the effect of predation on fish stocks and the threat to management efforts such as species reintroductions (Scordino et al, 2016). A better understanding about dietary preferences provides important evidence for the Indiana DNR DFW to determine the best way of addressing and balancing conflicting views about river otters.…”

North American river otters (Lontra canadensis) discriminate between 2D objects varying in shape and color

“…North American river otters live along the Atlantic and Pacific coasts of higher latitudes of North America as well as in the northern interior of the continent in Canada and almost all of the USA except the arid southwest (Johnson, 2000;Larivière & Walton, 1998). This widespread species inhabits rivers, marshes, estuaries, and coastal environments (Gallant, Vasseur, Dumond, Tremblay, & Bérubé, 2009;Guertin, Harestad, & Elliott, 2009;Johnson, 2000;Larivière & Walton, 1998;Scordino, Gearin, Riemer, & Iwamoto, 2016). North American river otters are considered to be a more gregarious species than other otters (Kruuk, 2006).…”

“…Conspecific recognition likely involves multiple sensory modalities, including vision (Kruuk, 2006). Across all studied environments and populations, river otters' primary food source seems to be fish, followed by crustaceans and insects, with opportunistic tendencies to infrequently pursue widely varied food sources including birds, mammals, reptiles, and amphibians (Crimmins, Roberts, & Hamilton, 2009;Fretueg, Martin, Widga, & Ruez, 2015;Guertin et al, 2009;Larsen, 1984;Penland & Black, 2009;Reid, Code, Reid, & Herrero, 1994;Scordino et al, 2016;Serfass, M. Rymon, & Brooks, 1990;Toweill, 1974). Otters seem to have preferences related to the size and speed of their prey (Crimmins et al, 2009), which likely indicates a preference for food that will yield the greatest metabolic payoff for the energy expended while foraging.…”

“…Otters seem to have preferences related to the size and speed of their prey (Crimmins et al, 2009), which likely indicates a preference for food that will yield the greatest metabolic payoff for the energy expended while foraging. Food consumption seems to be controlled by both dietary preferences and abundance of food sources depending on location and season (Crowley et al, 2013;Scordino et al, 2016). The ability to perceive visual features like shape and color may contribute to their ability to select preferred prey items.…”