Minnigiak: Forage fish ecology and population dynamics in northern Labrador under a changing climate

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Forage fish funnel energy between zooplankton and top predators and represent a key trophic link of marine ecosystems. Capelin (Mallotus villosus), sand lance (Ammodytes spp.) and Arctic cod (Boreogadus saida) are the main forage fish in the Labrador Sea. Variations in the abundance of these three species have cascading impacts on the whole ecosystem, including on fish, seabirds, and marine mammals with high socioeconomic value. Yet, the distribution and population dynamics of forage fish remain major knowledge gaps precluding our understanding of ongoing changes in the marine ecosystems of the region. The northern Labrador shelf is a unique area of the Arctic gateway characterized by very strong interannual and decadal variations in temperature and environmental conditions. These variations modify primary (algae) and secondary (zooplankton) productions, as well as the population dynamics and distribution of forage fish. The alternation between years colder and warmer than average also results in an overlap between boreal (e.g. capelin and sand lance) and Arctic (e.g. Arctic cod) species. The overarching and novel question this research program addresses is: How do short- and long-term variations in environmental conditions drive forage fish population dynamics at the Atlantic-Arctic gateway? Answering this question is critical to predict the resilience of marine ecosystems to changes in environmental conditions as well as to forecast the northern range expansion of boreal fish in the Canadian Arctic. Specific objectives include: (I) Documenting and forecasting changes in the distribution and abundance of capelin, sand lance and Arctic cod in relation to environmental conditions; (II) Measuring the dietary niche overlaps and interspecific competition between boreal and Arctic forage fish; and (III) Identifying the main drivers of capelin recruitment in northern ecosystems. The highly novel components of this program are twofold: First, it will identify the mechanisms driving changes in pelagic ecosystems at the northwest Atlantic-Arctic gateway, which remains a black box in a region at the forefront of global changes. Second, the unique combination of ship-based and moored broadband acoustic echosounders, environmental DNA, and trawls will increase the taxonomic, spatial, and temporal resolution of the forage fish surveys to a level never reached before at the Atlantic-Arctic gateway. In addition to training 5 HQP, this research program will contribute to advancing ecosystem-based management for sustainable commercial and cultural fisheries. Ultimately, it will improve our predictions of the resilience of Arcto-boreal marine ecosystems to climate change.