The nutritional condition of larvae of anchovy (Engraulis encrasicolus L.) in the outflow of the River Po (Northern Adriatic)
Abstract
Larvae of anchovy, Engraulis encrasicolus, were sampled in August 1995 along a transect across the outflow of the River Po. Their nutritional condition was determined by analysis of otolith daily growth rings and histological grading of tissues of the midgut, liver and trunk muscle. The growth rate of larvae 4-8 mm in length was higher for those sampled inshore (0.515 mm/day) compared with larvae from further offshore (0.417 mm/day). These data are supported by results from the histological assessment of nutritional status which showed larvae to be in poorer condition further offshore, where food availability was lower, than at the inshore sampling site where food availability was higher. Overall, an estimated 6% of inshore larvae were classified as starving compared with 22% from offshore. Nutritional condition also reflected the diel feeding rhythm of the larvae, with liver storage reserves being laid down following day-time feeding and then being utilised during the night-time period of non-exogenous feeding.
