DISTRIBUTION AND AGE STRUCTURE OF MACKEREL (SCOMBER-SCOMBRUS, L.) ANDHORSE MACKEREL (TRACHURUS-TRACHURUS, L.) IN THE NORTHERN COAST OF SPAIN, 1989-1994

This paper describes the seasonal and geographical distribution of mac kerel (Scomber scombrus L.) and horse mackerel (Trachurus trachurus L. ) in the northern coast of Spain (ICES Division VIIIc and Sub-division IXa North), based on commercial catches and bottom trawl surveys. Mea n monthly commercial catches were mapped by ICES statistical rectangle , and the quarterly distribution by ape group (0, 1, 2 and >2 years) a nd by Sub-division (Sub-division VIIIc East, VIIIc West and IXa North) are presented for the period 1989 to 1994 in the case of mackerel. an d 1990 to 1994 for horse mackerel. Series of catch per unit effort by age are also analysed for some commercial fleets. The age group distri bution (0, 1, 2 and >2 years) in autumn, based on information from bot tom trawl surveys, is presented for the whole area studied. The data a nalysis reflects clear seasonality of mackerel in the northern coast o f Spain. Nevertheless, in the case of horse mackerel in the same area, seasonality is not so evident. These results are discussed with respe ct to spawning and feeding migrations of these species in the Northeas t Atlantic.