Early life history traits of coastal pelagic fishes in the northern Benguela Current ecosystem off Namibia

Abstract

Several traits of larval stages of the three most important coastal pelagics species in the northern Benguela Current upwelling ecosystem (NBCE)- Sardinops sagax, Engraulis encrasicolus and Trachurus capensis were investigated. The study is based on samples from four consecutive research cruises conducted in the NBCE region during 2008 to 2011. All species showed maximum larval densities within the upper 50 m of the water column over the continental shelf during austral summer. Larvae fed mainly on planktonic crustaceans occupying a similar trophic level. T. capensis larvae and juveniles showed the highest degree of eurythermy and tolerated exposure to hypoxic conditions.They were characterised as voracious feeders with a high plasticity of prey items leading to a high feeding success. In contrast, nutritional condition of S. sagax larvae was affected by larval densities. In conclusion, T. capensis seems to be best adapted to present conditions in the NBCE, characterised by frequent intrusions of warm water, shoaling of hypoxic zones and a shift towards smaller copepods in the zooplankton community, probably leading to their higher recruitment success.