Stable Isotope Analysis Reveals Habitat Mediated Variability in the Ecology of Pacific Hagfish Eptatretus stoutii

The coastal shelves of the Northeast Pacific have supported fisheries for centuries, resulting in numerous studies on the ecology of target species. However, our understanding of species that are not actively targeted by fisheries, such as Pacific hagfish Eptatretus stoutii (Lockington 1878), is not as resolved. We conducted stable isotope analysis on Pacific hagfish from an experimental fishery within three distinct habitats along Canada’s west coast – a narrow fjord, a sound, and a continental shelf – revealing intraspecific variability in δ13C and δ15N isotopic signatures. Hagfish collected from the fjord had the lowest δ13C and δ15N isotopic signatures, those in the sound had intermediate values, and those from offshore on the continental shelf had the highest isotopic signatures. We propose that this trend is the result of varying amounts of terrestrial nutrient inputs based on proximity to shore, in addition to variable chemoautotrophic activity. Terrestrial nutrients are introduced into marine food-webs through run-off and are known to exhibit more depleted isotopic signatures than marine-based nutrients. Chemoautotrophy also produces low δ13C and δ15N signatures. These results provide novel insight on stable isotope signatures in Pacific hagfish in British Columbia and may act to inform future research on this species.