Diet and isotopic niche overlap elucidate competition potential between seasonally sympatric phocids in the Canadian Arctic

Arctic seals as tracers of environmental and ecological change

“…These findings highlight the power of using δ 15 N AA when examining spatial variation in TP of predators and demonstrate the need to account for variation in the δ 15 N of the baseline to avoid misinterpretation of δ 15 N bulk in consumers. Harp seals are generally larger than ringed seals (Ogloff et al 2019). While harp and ringed seals feed on broadly similar prey species, stomach content analysis has shown that ringed seals have a greater reliance on smaller fish and invertebrates in the upper water column compared to harp seals, which rely to a greater extent on larger fish at deeper depths, probably related to differences in body size and habitat preferences (Wathne et al 2000;Ogloff et al 2019).…”

“…Ringed and harp seals are abundant near-top trophic level generalists that have a wide distribution. Generally, their diet consists of a large variety of pelagic invertebrates and forage fish (Wathne et al 2000;Folkow et al 2004;Nordøy et al 2008;Lindstrøm et al 2013;Ogloff et al 2019). Given these characteristics, ringed and harp seals are suitable model species with which to quantify spatial variation in food web structure.…”

Plastic ingestion, retention, and transport in animals from the eastern Canadian Arctic

“…Approximately 21% (n = 31) of the seal stomachs were empty, which is similar to what has been reported in other seal diet studies (Gjertz and Lydersen, 1986;Holst et al, 2001;Labansen et al, 2007;Ogloff et al, 2019;Siegstad et al, 1998). The contents of the seal stomachs were fairly homogenous with either exclusively euphausiids (n = 60) or exclusively small fish (n = 19) making up the bulk of the stomach contents, however, a few stomachs had a mix of euphausiids and fish (n = 9) (Figure 3.2A, Figure 3.2B [I, II]).…”

Harp Seals: Monitors of Change in Differing Ecosystems

“…As in other areas NWA harp seals also rely on invertebrates and polar cod in the north, and primarily forage fish in the south (e.g., Kapel, 1995;Finley et al, 1990;Lawson and Stenson, 1997;Ogloff et al, 2019). However, there is considerable geographic and seasonal variation in the prey species consumed (e.g., see Stenson, 2012).…”