Long-term changes in the distribution of the offshore northern shrimp (Pandalus borealis) in Icelandic waters

The aim of this study was to analyse long-term changes in the distribution of the offshore shrimp stock in Icelandic waters from 1988–2013 and to analyse whether recent warming had impacts on or shaped the distribution. The northern shrimp (Pandalus borealis) is distributed throughout the colder parts of the North Atlantic and Pacific Oceans and is found both inshore and offshore in Icelandic waters. The offshore population is in the deep waters north and east of Iceland, at depths of 200 m or more. In recent years, surface temperature on Icelandic fishing grounds has increased by 1 to 2°C and since 1996, temperature north of Iceland has been relatively high. Cod abundance on the shrimp grounds also showed a gradual increase in the study period, and at the same time, shrimp abundance in offshore waters declined, and reached a historically low level in 2004. In this study, the centre of gravity of the shrimp distribution was estimated for each year and its displacement examined in terms of main influencing factors which were the offshore shrimp catch and the cod biomass index from the annual offshore shrimp surveys. In addition, factors influencing the shrimp abundance were examined and the increasing sea surface temperature was found to be the main negative influence. The results therefore indicate that besides ocean temperature, both predation and fishing effort may have influenced the distribution and/or abundance of the northern shrimp off Iceland