Publication Abstract

Patterns of distribution, spawning, and growth in North Atlantic cod: the utility of inter-regional comparisons

K.M. Brander

Cod populations throughout the North Atlantic follow a common life history pattern, but with considerable regional variations in their growth rate, age of maturity, migration patterns, and timing of spawning. The comparative method is a powerful tool both for identifying factors which shape life history patterns and for investigating them quantitatively. Most studies of cod population dynamics are carried out for stock assessment and management purposes and are confined to interpreting only changes within stocks. There is a strong case for undertaking comparative studies and for treating cod as a species rather than as a collection of discrete units. Two studies which make comparisons between stocks are presented in order to bring out the benefits of a comparative approach. The first concerns processes governing recruitment and in particular the hypothesis that differences in timing of cod spawning throughout the range are due to variability in the timing of plankton production. The second investigates the effect of temperature on growth in different stocks. The results suggest that temperature is responsible for most of the observed differences in growth and that the effect is big enough to have significant consequences for assessment of the impact of climate change and also for short-term catch forecasts.

Reference:

K.M. Brander, 1994. Patterns of distribution, spawning, and growth in North Atlantic cod: the utility of inter-regional comparisons. ICES Marine Science Symposium, 198: 406-413.