Effect of light intensity and eye development on prey capture by larval striped bass Morone saxatilis

Abstract

The efficacy of visual and non‐visual feeding among pelagic striped bass Morone saxatilis larvae adapted to a turbid estuary was determined in the laboratory in clear water. Capture of Artemia salina (density 100 l−1) was significantly affected by the interaction between age of larvae (range: 8–25 days post‐hatch, dph) and light intensity (range: 0–10·6 μmol s−1 m−2 at the water surface). Visual feeding by larvae aged 9–11 dph was highest in dim light (0·086–0·79 μmol s−1 m−2), with fish capturing up to 5 prey larva−1 h−1. As the larvae grew, prey capture in brighter light improved, associated with an increasing proportion of twin cone photoreceptors and improving ability of the retina to light‐ and dark‐adapt. By age >22 dph, mean prey capture was greatest at highest light intensities (0·79 and 10·6 μmol s−1 m−2) exceeding 100 prey larva−1 h−1. Incidence of feeding larvae generally improved as the larvae grew, reaching >80% in all light intensities from 16 dph onwards. The lower threshold for visual feeding, between 0·0084 and 0·03 μmol s−1 m−2, remained constant as the larvae grew, despite an increasing density of rod photoreceptors. Below this threshold, non‐visual feeding was evident at a low rate (<6 prey larva−1 h−1) that was independent of larval age.