Spawning season and temperature relationships for sardine (Sardina pilchardus) in the eastern North Atlantic

Spawning temperature preferences for sardine (Sardina pilchardus) in the eastern North Atlantic were determined from egg survey data. These were compared with climatological temperature cycles (1986-2002) derived from satellite observations, by geographical region, to predict spawning seasons. Optimum spawning temperatures were determined as 14.0-15.0 degrees C from the English Channel to Portugal and 16.0-18.0 degrees C for all north-west African regions. Spawning seasons were closely related to the general latitudinal trend of the annual temperature cycle, with modification by upwelling in the western Iberian and northwest African regions. Sonic differences between temperature-based spawning season predictions and field observations were related to variations in seasonal plankton production. Correlations in the annual time-series of favourable spawning temperatures suggested relatively strong linkages between the southern areas from Portugal to Senegal. There was no consistent relationship between annual variations in extent of temperature-predicted spawning seasons and observed field abundance of eggs.