Feeding ecology of maturing sockeye salmon (Oncorhynchus nerka) in nearshore waters of the Kodiak archipelago

Abstract

The diet and feeding behavior of maturing sockeye salmon (Oncorhynchus nerka) were investigated during the final marine phase of the spawning migration, prior to reentering natal streams. The stomach contents of commercially caught sockeye salmon, migrating within the nearshore waters of the Kodiak Archipelago during 1998 and 1999, were examined to determine the level of feeding activity and taxa of dominant prey items. Samples were collected throughout the majority of the migration (early June to late August) from areas known to be used principally as migration corridors, and from areas proximate to several natal streams. Dominant prey of sockeye salmon were decapod larvae, Pacific sandlance (Ammodytes hexapterus), and the pteropod Limacina helicina. Feeding activity levels and dominant prey taxa varied both between areas and within areas over time. Feeding activity levels for the population appear to gradually diminish, rather than abruptly ceasing, as sockeye approach their natal streams to spawn.