Summer habitat use and feeding of juvenile Arctic charr, Salvelinus alpinus, in the Canadian High Arctic

We used an array of fixed acoustic receivers (N = 42) to track the summer marine movements of 121 anadromous Arctic char (Salvelinus alpinus) equipped with acoustic transmitters at three locations in the Cambridge Bay region, where commercial and subsistence fisheries target the species. The timing of transitions between salt and fresh water was influenced by the putative river of origin of tagged individuals, but not by their size or sex. Females, however, were more likely to remain proximate to rivers where they were tagged throughout the summer. A majority of fish migrated west from their rivers of origin, primarily moving between estuarine environments. Individuals occupied estuaries for several days between bouts of marine movement, and these periods of residency coincided with spring tides in some estuaries. We also recorded increased numbers of detections on receivers located less than 1.5 km from the coast, indicating a preference for nearshore habitats. Finally, we report evidence of extensive stock mixing throughout the summer, including at known fishing locations and periods, a finding with implications for fisheries management.

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Life history variation in Arctic charr (Salvelinus alpinus) and the effects of diet and migration on the growth, condition and body morphology of two Arctic charr populations in Cumberland Sound, Nunavut.

Arctic Science ◽

10.1139/as-2019-0036 ◽

2021 ◽

Author(s):

Angela Young ◽

Ross F. Tallman ◽

Derek H. Ogle

Keyword(s):

Growth Condition ◽

Life Histories ◽

Salvelinus Alpinus ◽

Arctic Charr ◽

High Arctic ◽

Feeding Strategies ◽

Life History Variation ◽

Body Morphology ◽

And Migration ◽

Size At Age

Arctic charr (Salvelinus alpinus) are phenotypically plastic with multiple dietary-morphological relationships observed throughout their circumpolar range. Feeding strategies often differ between Arctic charr life histories and can impact size-at-age and morphological attributes. We examined growth, condition, and body morphology for two high Arctic populations of Arctic charr with anadromous and landlocked life histories. Anadromous Arctic charr had higher growth rates, achieving mean lengths two times those of landlocked Arctic charr by age 10 and had higher overall condition, particularly in the fall. Ontogenetic shifts in diet were suspected in both populations, with an abrupt shift to marine feeding in the anadromous population and a gradual shift to piscivory in the landlocked population. Morphological differences between life histories manifested most predominantly in larger eye diameter, longer pectoral and pelvic fins, and longer upper jaws of landlocked Arctic charr, suggestive of piscivorous feeding specialization of landlocked fish >350mm. Our findings emphasize the benefits that marine feeding can have for growth and condition of freshwater fishes in Arctic environments and also convey the necessity of adaptive feeding strategies to optimize growth and condition in fishes inhabiting low-production lacustrine habitats.

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