Migration, Dispersal, and Gene Flow of Harvested Aquatic Species in the Canadian Arctic

Migration occurs when key aspects of the life cycle such as growth, reproduction, or maintenance cannot all be completed in one location. The Arctic habitats are variable and Arctic species are often migratory. The predictable nature of migrations in both space and time allow Arctic people to harvest fishes and marine mammals. We describe migratory/dispersal behavior in four types of taxa from the Canadian Arctic: anadromous and freshwater fishes, marine fishes, marine invertebrates, and marine mammals. Patterns of migration are remarkably different between these groups, in particular between distances migrated, seasonal timing of migrations, and the degree of reproductive isolation. Migratory anadromous and freshwater fishes become adapted to specific locations resulting in complex life histories and intra- and inter-population variation. Marine mammals not only migrate longer distances but also appear to have distinct demographic populations over large scales. Marine fishes tend to be panmictic, probably due to the absence of barriers that would restrict gene flow. Migratory patterns also reflect feeding or rearing areas and/or winter refugia. Migratory patterns of harvested aquatic organisms in the Canadian north are extremely variable and have shaped the north in terms of harvest, communities, and culture

A review of Canadian Arctic killer whale (Orcinus orca) ecology

The killer whale (Orcinus orca Linnaeus, 1758) is a widely distributed marine predator with a broad ecological niche at the species level with evidence of specialization and narrow ecological niches among populations. Their occurrence in Canadian Arctic waters is limited by sea ice and it has been suggested that climate warming, which has caused increases in the area of ice-free water and duration of the ice-free season, has led to an increased killer whale presence during the open-water period. In this review, we summarize our knowledge of Canadian Arctic killer whale demographics and ecology, synthesizing published and previously unpublished information in a single document. More specifically, we summarize our knowledge of killer whale population size and trends, distribution and seasonality (including results from recent satellite-tracking studies), feeding ecology, and threats, and identify research priorities in the Canadian Arctic. Despite increased research effort during the past decade, our demographic and ecological knowledge remains incomplete. An improved ecological understanding is necessary for effective management of killer whales and their prey, species of ecological, economic, and cultural importance to Canadian Inuit and to the marine ecosystem. This knowledge will allow us to better understand the ecological consequences of a changing Arctic climate.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

No microplastics detected in the first assessment of Atlantic walrus stomachs from Nunavut, Canada

As plastic pollution continues to persist at a global level, the Arctic has drawn increased research interest as a possible sink for marine pollutants. Plastic and microplastics are highly durable and can be transported across vast distances. To date, only a handful of studies have directly assessed microplastics in Arctic mammals. In Canada, it is still unclear whether they show a concrete propensity for microplastic retention and ingestion. Atlantic walruses (Odobenus rosmarus rosmarus (Linnaeus, 1758)) are economically and culturally important for Inuit and are key predators in Arctic marine ecosystems. Here, we present the first assessment of microplastic pollution in Canadian walruses and the first gastrointestinal assessment of microplastic in walruses globally. Since microplastics accumulate in benthic sediment and animals, we expected that walruses may ingest and retain microplastic contaminants when sifting in search of prey or when eating contaminated bivalves and invertebrates. We detected no microplastics ≥80 µm in our evaluation of 36 walruses from five communities in NU, Canada. Our results suggest that walruses in this region do not retain microplastic particles ≥80 µm in their stomachs, which is consistent with findings in other pinnipeds that have been evaluated in Arctic Canada

Tracing carbon flow and trophic structure of a coastal Arctic marine food web using highly branched isoprenoids and carbon, nitrogen and sulfur stable isotopes

Climate-driven alterations of the marine environment are most rapid in Arctic and subarctic regions, including Hudson Bay in northern Canada, where declining sea ice, warming surface waters and ocean acidification are occurring at alarming rates. These changes are altering primary production patterns that will ultimately cascade up through the food web. Here, we investigated (i) the vertical trophic structure of the Southampton Island marine ecosystem in northern Hudson Bay, (ii) the contribution of benthic and pelagic-derived prey to the higher trophic level species, and (iii) the relative contribution of ice algae and phytoplankton derived carbon in sustaining this ecosystem. For this purpose, we measured bulk stable carbon, nitrogen and sulfur isotope ratios as well as highly branched isoprenoids in samples belonging to 149 taxa, including invertebrates, fishes, seabirds and marine mammals. We found that the benthic invertebrates occupied 4 trophic levels and that the overall trophic system went up to an average trophic position of 4.8. The average δ34S signature of pelagic organisms indicated that they exploit both benthic and pelagic food sources, suggesting there are many interconnections between these compartments in this coastal area. The relatively high sympagic carbon dependence of Arctic marine mammals (53.3 ± 22.2 %) through their consumption of benthic invertebrate prey, confirms the important role of the benthic subweb for sustaining higher trophic level consumers in the coastal pelagic environment. Therefore, a potential decrease in the productivity of ice algae could lead to a profound alteration of the benthic food web and a cascading effect on this Arctic ecosystem