A correlation between phototactic response and first-feeding of Atlantic halibut (Hippoglossus hippoglossus L.) larvae
Abstract:
The correlation between positive phototaxis and
feeding incidence at first-feeding for groups of Atlantic halibut larvae
ranging in age from 210 to 240 degreedays, post hatch, was examined.
Phototactic response was measured as the fraction of larvae that responded
by horizontal swimming towards a light source, and the median travel
distance for the responding fraction of larvae. Within the ranges
investigated, larval age, size or proportion of deformed larvae had no
significant effect on the phototactic response, or on the feeding incidence
(deformed larvae excluded from analysis). The fraction of larvae responding
phototactically and the median travelling distance for responding larvae
were significantly correlated. Feeding incidences after 24 and 48 h
were also significantly correlated with both measures of phototactic
response. The possibility of using phototactic response in quality
assessment is discussed.
(Institute of Marine Research, Austevoll Aquaculture
Research Station, N-5392 Storebø, Norway. e-mail: Oerjan.Karlsen@imr.no)