Habitat characterization of capelin along East Greenland: insights from hydrographic conditions and feeding distribution patterns

The migration routes of the Iceland-East Greenland-Jan Mayen capelin are presumed to rely on currents and, consequently, the hydrographic conditions in their habitat. This study aims to address our knowledge gap regarding the distribution of capelin with respect to the hydrographic features and prey availability at their present feeding grounds in autumn along East Greenland. We analyzed data from two sections at 70° and 72°N latitude, showing that capelin is present in the coastal and shelfbreak branches of the East Greenland Current down to a depth of nearly 300 m, which primarily comprises Polar Surface Water and Atlantic-origin water. Capelin was present both on and off shelf in a wide range of temperature and salinity conditions with inter-annual variability. A higher abundance of capelin was found in areas with steeper slope, indicating higher velocity, which is potentially associated with high-nutrient influx creating productive feeding grounds. These areas also corresponded with weaker stratification in the water column. A close spatial overlap between capelin and their main prey, krill, also suggests that capelin moves across hydrographic gradients, potentially following their prey or due to an innate diel vertical migration behavior. Our study provides insights into the habitat characteristics of capelin in this region, contributing to a better understanding of how this economically vital species may respond to changing ocean conditions.