Abstract
Arctic charr (Salvelinus alpinus (Linnaeus, 1758)) 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 >350 mm. 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.
Highlights
Diet and feeding ecology play an important role in an organism’s growth and development throughout its life cycle and may contribute to shaping its life history
We examined potential differences between anadromous and landlocked populations for each morphometric variable with general additive models (GAM; Wood 2017) that included a smoother term for Fork length (FL), as we expected each morphometric variable to be related to FL
Study sites yielded notably different sample sizes with 409 anadromous Arctic charr sampled from PG027 and 69 landlocked Arctic charr sampled from Qinniqtuq across all sampling seasons and years
Summary
Diet and feeding ecology play an important role in an organism’s growth and development throughout its life cycle and may contribute to shaping its life history. Ontogenetic niche shifts (e.g., changes in feeding, habitat use, and morphology) are common in species with variable life histories (Werner and Gilliam 1984; Fryxell and Sinclair 1988; Post 2003; Kimirei et al 2013) These shifts are related to behavioral or morphological changes during ontogeny, are often correlated with discrete growth periods in the species’ life history (Werner and Gilliam 1984), and may be either as dramatic as metamorphosis in amphibians or as subtle as diet shifts in fishes (Werner and Gilliam 1984; Olson 1996). These shifts in diet may be necessitated by seasonal food availability, as is the case with seasonal migrations made by some salmonids that inhabit low productivity and highly seasonal freshwater habitats such as those found in the Arctic (Hendry and Stearns 2004)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
