Understanding ringed seal foraging ecology through Inuit knowledge and stomach content analysis
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Date
2021-08-26
Authors
Ghazal, Maha
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Abstract
Ringed seals (Pusa hispida) are opportunistic predators but primarily feed on Arctic cod (Boreogadus saida) and lipid-rich pelagic crustaceans. Recently, shifts in diet have been observed. We used semi-structured interviews and stomach contents analysis to describe ringed seal diet and foraging ecology. Interviews (n=23) were conducted with hunters from Arctic Bay, Pangnirtung, and Pond Inlet, Nunavut. Ringed seal stomach samples (n=201) were harvested from Admiralty Inlet, Cumberland Sound, and Eclipse Sound and samples containing prey contents (n=166) were analysed.
Hunters observed ugak (cod) and kinguk (amphipods) in the stomachs of ringed seals, year-round, across spatial scales, and within all age classes. The flavour of ringed seal meat was variable across space and time, with some associating the flavour with ringed seal prey. Some participants identified specific areas where ringed seals foraged, for example, the floe edge, polynyas and in areas of current, while most responses pointed to widespread feeding. Ringed seals were described as feeding year-round, except for the moulting and basking period when their stomachs were typically empty or had fewer contents. Some age-related differences in diet were observed by interviewees, specifically that juveniles consumed more kinguk than other prey types when they were first weaned.
Stomach contents revealed Arctic cod and Hyperiidae were most abundant and frequently occurring of fishes and invertebrates, respectively. Multivariate tests found a significant effect for region, year of harvest, month of harvest, age class, and the interaction between age class and region. Univariate tests indicated significant differences between regions in the prey counts of Arctic cod and Euphausiacea. Arctic cod had higher abundance and biomass in both northern regions than in Cumberland Sound, whereas Euphausiacea was not present in either of the northern regions. Temporal differences were driven by Euphausiacea among years and Amphipoda among months. Amphipoda differed significantly among age classes with young of the year consuming the highest abundance and biomass, followed by subadults, and adults. Understanding the foraging ecology of ringed seals will help wildlife managers better understand the evolving dynamics of the Arctic food web and determine potential impacts on species at higher trophic levels.
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Keywords
Arctic, Ringed seal, Inuit Knowledge, Stomach content analysis, Foraging ecology