Data and code from: Marine migrations and trophic niche use of Arctic charr in southwest Greenland fjords with contrasting influxes from glacial runoff

Arctic charr is a partially migratory salmonid often undertaking annual
marine migrations for feeding. As migration is an adaptive life-history
trait, climate-driven environmental changes can alter selective pressures
shaping movement behavior. To assess climate-related influences on
migratory patterns and trophic niche use, we combined acoustic telemetry,
otoliths, and stable isotope analysis to study populations in two
Southwestern Greenland fjords differing in glacial runoff: Igaliku and
Ikersuaq. Anadromous charr in Igaliku used the full fjord, traveling up to
21 km from their home river, while those in the more glacially influenced
Ikersuaq remained nearshore with shorter movements (9km). Despite similar
marine feeding duration (48 vs. 54 days), Igaliku fish exhibited lower
marine feeding intensity. Arctic charr in Igaliku experienced warmer (8.2
ºC) conditions than those in Ikersuaq (5.8 ºC), with estuaries (Igaliku
8.2 ºC; Ikersuaq 7.6 ºC) consistently as warm or warmer than marine areas
in both systems. Findings suggest Arctic charr is constrained by fjords
with high glacial runoff and may shift to more open waters, thereby
altering diet, growth rates and life-history strategies under future
climate change scenarios.