How to sample larval fish for taxonomical and ecophysiological studies in shallower temperate coastal ecosystems?

Abstract

Recruitment predictions for fish are often difficult to make due to the intrinsic variability of species and the incomplete sampling procedures. The aim of this study was to analyse the fish larval catches (abundance, diversity, size and damage) from a standard 500 µm ichthyoplankton net and different light traps (structure, size and light intensity) in temperate coastal turbid waters. Catches from different gears were always made on the same date or season, same location and same tidal phase. Results showed that light traps captured significantly bigger larvae (almost post-flexion) than those captured with the ichthyoplankton net, nevertheless the diversity was lower. Clupeidae species were the most represented taxon; however, the traps also caught Atherinidae, Gobiidae, Sparidae, Soleidae and Labridae. The light traps were less stressful devices, allowing the capture of live and active larvae. This showed other possible uses for the light trap, e.g. larval behavioural and physiological studies. Light traps constitute a good complementary sampling option for post-flexion larvae, being aware of species selectivity associated with their use.