Vertical distribution and population structure of the necrophagous amphipod Eurythenes gryllus in the West European Basin

Abstract

During 3 cruises to the West European Basin benthopelagic nekton was captured by use of an acoustically released vertical array of 8 to 10 baited traps. The traps were exposed from 5 to 1000 m above the bottom. Nearly all of the 1962 amphipods trapped in total during 18 deployments were identified as the lysianassid amphipod Eurythenes gryllus . Most individuals were recovered from traps deployed 15 m above the sea floor. Above 30 m, catch rates decreased significantly. However, the vertical distribution differed by age and sex: indeterminate juveniles and adult females were only trapped up to 50 m above the bottom. Catch rates of juvenile males and females decreased with increasing distance from the bottom, whereas adult males showed a bimodal distribution with maxima at 15 and at 300 m above the sea floor. Males were prevalent in all but 2 deployments.