Trends in strandings and by-catch of marine mammals in north-west Spain during the 1990s

Strandings of marine mammals on the north-western Spanish coast (Galicia.) have been systematic ally recorded since 1990. A total of 1433 marine mammals belonging to 15 species was recorded front 1990 to 1999. The most frequently recorded species stranded were common dolphin (47%), bottlenose dolphin (11%) and harbour porpoise (7%). The number of strandings recorded increased annually over the study period, probably reflecting an increased observer effort. During 1996-1999, an average of 1.65 animals were stranded annually for each 10 km of coastline, the highest density of strandings recorded on the Atlantic coast of the Iberian Peninsula. More than 80% of the strandings were located on the western coast of Galicia, mainly in autumn and winter. During the study period, 42 proven incidental catches were recorded, although signs of by-catch were seen in a further 198 animals. The average size of stranded common dolphins and the proportion of males both increased towards the end of the calendar year.