Influence of climate on recruitment and migration of fish stocks in the North Sea
Original version
This report is not to be cited without prior reference to the authorsAbstract
For several decades one of the prime targets within fishery science has
been to be able to understand and explain the great variability in the
success of survival from egg to mature fish. One of the reasons why such
effort has not lead to any clear and quantifiable conclusions, is probably
that the direct and indirect influence of the physical climate has so far
been underestimated.
22 years of hydrographic data taken during summer over most of the
northern and central North Sea, and meteorological data from a station
outside western Norway, have been used to derive climatic parameters
assumed to be of prime importance for the biological productivity of the
North Sea. These time-series together with recruitment and spawning
stock size data from the indiuidual ICES working groups, have been used to
construct empirical models demonstrating that e.g. more than 70% of the
year to year recruitment variability of several of the fish stocks may be
explained by the climate/weather prior to and during the time of larval
stages.
In addition to demonstrate which climatic factors being most
important for the biological prosesses, the results of the models indicate
that realistic forecasts of recruitment can be given already within the
summer of the spawning year. This possibility is of great importance to
better manage the fish resources.