Horizontal and vertical distribution patterns of ichthyoplankton under intense upwelling regimes off Namibia

Abstract

Horizontal and vertical distribution patterns of eggs and larvae of selected fish species in the waters off Namibia during intense upwelling seasons are discussed. The material was collected in the course of several cruises carried out off Namibia during winter and spring. The coastal area was under the influence of strong upwelling, characterized by surface isotherms running parallel to the coast and, except for some slope stations, the water column from the surface to 200 m deep showed almost no stratification. Analysis of vertical distributions showed that eggs and larvae of all species were widely distributed throughout the water column, with a maximum within the upper 100 m. Spatial patterns of ichthyoplankton distributions in the northern Benguela during intense upwelling seasons show clear segregation into coast and slope (oceanic) areas. Two species, lanternfish Lampanyctodes hectoris and lightfish Maurolicus muelleri, dominated the oceanic area. In the coastal area, the most abundant species was Sufflogobius bibarbatus. During one of the surveys, large numbers of eggs and larvae of slope species were found much nearer the coast than usual south of 26°S. This finding is discussed in relation to local inflow of oceanic water into the coastal area, a feature recorded during the cruise. © 1992 Taylor & Francis Group, LLC.