Impact of spectral composition on larval haddock, <i>Melanogrammus aeglefinus</i> L., growth and survival

Abstract

In a small-scale culture experiment, larval haddock, Melanogrammus aeglefinus L., were raised under various combinations of light quality [blue (470 nm), green (530 nm) or full-spectrum white light] and light intensity [low (0.3–0.4 µmol s−1 m−2) or high (1.7–1.9 µmol s−1 m−2)], and in total darkness (both fed, and starved). Larval growth (0.9% day−1 in standard length; 2.4% day−1 in body area) was not significantly different between any combination of coloured light. At the time of total mortality in the starved treatment, survival was significantly reduced under low intensity, full-spectrum white light (13%) vs. all other coloured light treatments (68%). Larvae raised under both continuous dark treatments (fed and starved) exhibited morphological changes associated with irreversible starvation (point-of-no-return). Lack of a pronounced effect of light quality on larval haddock growth probably results from a combination of plasticity in early larval vision, and enhanced encounter rates between larvae and prey at the relatively high prey densities used in aquaculture.