The emergence period of sea trout fry in a Lake District stream correlates with the North Atlantic Oscillation

The date of fry emergence over 30 years in a sea trout nursery stream, predicted by an individual-based model, correlated significantly (r=0.660, P<0.001) with an index of the North Atlantic Oscillation. Water temperature is the main driving variable in the model and stream temperature also correlated significantly (r=0.662, P<0.001) with the index, providing a probable causal link. Therefore, the inter-annual variations in emergence may not be unique to this one stream, but may be typical of other trout streams with similar climatic conditions. (C) 2000 The Fisheries Society of the British Isles.