Ontogenic migrations of horse mackerel along the Iberian coast

This paper gives a description of the horse mackerel ontogenic migrations along the Iberian Atlantic coast, based on bottom-trawl survey data covering the period 1985-2003. The estimates of abundance and mean age from each haul were modelled as a function of year, area and depth and graphs were made showing the proportion of the abundance indices in each area of the coast for each year class. The hypothesis of ontogenic migrations of horse mackerel along the Iberian Atlantic coast is supported by the results obtained. These migrations seem to have two directions: one along the coast line and another perpendicular to the coast line, through different depths. The fish migrating through the Spanish area, from Biscay to North Galicia, are probably coming from the stock distributed from Norway through the west of the British Isles, with a southern boundary around Cape Finisterre. Off the Portuguese coast, most year classes seem to recruit to the northwest area, moving progressively to south, and in some cases, after reaching 7 years of age, returning back to northern waters.