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