The Effect of Supplementary Algal Feeding of a Hatchery Breeding Stock of <i>Ostrea Edulis</i> L. on Larval Vigour

Abstract

Adult European flat oysters, Ostrea edulis L., receiving a food supplement of the unicellular alga Tetraselmis suecica (Kylin) Butch, during laboratory conditioning for spawning produced more broods of larvae than oysters receiving only the natural phytoplankton in the seawater supply. Many of the broods from adults receiving this extra food were liberated sooner, and these larvae grew at an enhanced rate and provided greater spat yields than the broods from the control stock. The viability of larvae, which was significantly correlated with their lipid, and in particular neutral lipid, proportion at the time of liberation, declined as the length of the stock-conditioning period prior to female spawnings increased. This may be related to the decline in the dry meat weight and the condition factor of the adult oysters during the experiments irrespective of the feeding regime. The extra algal ration provided a check to the decline in dry meat weight of the food-supplemented adults.