Growth of juvenile Norwegian spring-spawning herring in relation to latitudinal and interannual differences in temperature and fish density in their coastal and fjord nursery areas

Abstract

Abstract Husebø, Å., Slotte, A., and Stenevik, E. K. 2007. Growth of juvenile Norwegian spring-spawning herring in relation to latitudinal and interannual differences in temperature and fish density in their coastal and fjord nursery areas. – ICES Journal of Marine Science, 64: 1161–1172. Norwegian spring-spawning herring (Clupea harengus) spawn in February and March along the Norwegian coast from 58°N to 69°N. The larvae are transported north with the coastal current, and in autumn, the main part of the 0-group is found in the Barents Sea, and a smaller and variable fraction ends up in coastal and fjord nursery areas that experience a wide range of environmental conditions and fish densities. Based on data from herring 0–2 years old collected from 1970 to 2004, there is a positive relationship between temperature and the growth of this coastal component, in terms of length, weight, condition factor, and annual otolith increment width, and a negative relationship between acoustic abundance and the same growth indices. In general, juvenile growth decreased northwards along the coast concurrently with decreasing summer and autumn temperatures and increasing acoustic abundance. It seems, therefore, that there may be interference in the relationship between juvenile herring growth and temperature, attributable to variable recruitment, currents, larval drift, and advection into the fjords, causing latitudinal and interannual differences in fish density, and hence variable competition for food.