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Atmospheric and oceanographic variability off the northern Iberian Peninsula in the 1990s is described from climatological databases and Spanish hydrographic surveys. The wind regime during the dccade can be divided into two principal periods. In the first, northerly (upwelling favourable) winds are prom inent, while in the second, southwesterly winds dom inate, resulting in diminished upwelling, an increase in sea surface tem peratures and the occurrence of the winter polew ard current. In the sub­surface waters during summer, a w arm ing trend through the 1990s of between 0.02 and 0.05°C year-1 is found, with the maximum am plitude between 150 and 200 m. The w arm est year was 1998. Salinity also varied during the decade, with higher salinities generally reflecting an increase in the poleward current and low salinities indicating advection from the inner Bay o f Biscay. In 1995/1996 and 1997/1998, a strong winter surface Poleward Current carrying warm, salty water was present along the Portu­guese coast and reached the southern Bay o f Biscay. It contributed significantly to the heat content in the upper 500 m of the w ater column. The intensification o f the Poleward Current is associated with increased onshore E km an transport during autum n in western Galicia. Sea level variability also reflects wind changes with stron­ger southwesterly winds resulting in higher levels. Mean sea level increased from 1993 to 1997, giving a somewhat greater increasing trend for the last decade com pared to the long-term over the past 55 years. Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access the remaining articles please click on the keyword "MSS Vol. 219".

Time-series (1967 -1997) of environmental variables such as air and sea surface tem­perature (SST), precipitation, wind, Ekman transport, and mean sea level, as well as time-series (1985-1997) of recruitment of horse mackerel, were studied in Atlantic Ibe­rian waters. All time-series were analysed for autocorrelation. The results indicate a statistically significant relationship between the North Atlantic Oscillation and air temperature in Santander. In western Iberia, winter Ekman transport is significantly correlated with the annual Gulf Stream position and sea level with the winter Gulf Stream position. Horse mackerel recruitment is negatively correlated with the annual and spring values of air temperature in the Cantabrian Sea and SST and air tempera­ture in western Iberia. Correlation between recruitment and upwelling index is signifi­cant in spring and summer. Recruitment is also negatively correlated with the annual and winter Ekman transport. After multicolinearity analysis, a multivariate regression model of non-correlated variables (air temperature in Vigo and upwelling index) from April to September has been applied and explains 81.63% of the variance.Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access the remaining articles please click on the keyword "MSS Vol. 219".

Fluctuations in the Iberian stock in the period 1980-1989 have been examined, taking into account what is known of the biology of the species, oceanic and atmospheric parameters, and the fishing effort directed at this stock. During this period, there have been significant changes in recruitment, which was good in 1983 and 1987 and poor in 1982, 1985, 1986, and 1988. Some links between recruitment anomalies and environmental parameters (surface temperatures, prevailing winds, sea level) have been identified. Variations in recruitment can be explained on the basis of fluctuations in “environmental windows" during the periods of spawning and larval drift. The success of spawning is controlled by the existence of a favourable environment during larval drift into areas with weak upwelling and abundant food.