Variation in size and growth of West Greenland capelin (Mallotus villosus) along latitudinal gradients

Abstract

Capelin (Mallotus villosus) is the dominant pelagic species in the West Greenland ecosystem. Historical data are re-examined and new data are presented on the size distribution and the growth pattern of capelin along latitudinal gradients of temperature and other growth factors extending over a distance of 1300 km. The average size of capelin increases with latitude. Fish 3 years old were 48 mm larger (54) at the secondmost northern station compared with the most southern one. Otolith analysis revealed a significant effect of age as well as area on back-calculated growth. Hence, at all ages, fish grew faster in the north than in the south. Average somatic growth across areas in the first and fourth years was 56 and 15 mm, respectively. Temperature data suggest a 2°C difference in temperature between areas, temperatures being warmest in the north. Hence, the increase in temperature with latitude explains much of the latitudinal growth gradient and suggests a growth difference in West Greenland capelin of 0.4-0.6 cm °C-1 year-1. However, the difference in growth and size distribution between northern and southernmost stations, where temperatures are similar, suggests that other factors, such as differences in available prey and diet composition, also contribute to the differences. © 2010 United States Government, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center.