Captive breeding of the caramote prawn (Penaeus kerathurus) for restocking purpose: effect of single- and mixed-algal diets on larval growth and survival

Abstract

Attempts to breed crustacean species of commercial interest to promote the conservation, restoration and enhancement of the stocks are increasing. Optimization of diet for larval growth is a crucial step for successful actions. Here we focus on the caramote prawn (Penaeus kerathurus), a primary target of small-scale fishery because of its high commercial value in the North Mediterranean region and particularly in Italy. Three species of microalgae (Isochrysis galbana, Nannochloropsis oculata, and Chaetoceros calcitrans) with different fatty acid contents were used to feed caramote prawn larvae as monospecific diets. Further, C. calcitrans in combination either with I. galbana or N. oculata were tested as mixed diets. Measurements of developmental performance were taken until the larvae metamorphosed to Mysis 1, while survival rate was estimated at day 10 of benthonic post-larval stage. Larvae fed on mixed diets performed as well or slightly better than those fed on single-C. calcitrans and -N. oculata diets both in terms of development and survival, while larvae fed with I. galbana diet performed worse overall. Diets that performed best (C. calcitrans and I. galbana mix) are known to have a higher proportion of the essential fatty acids eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), respectively. We suggest that mixed-algal diets could improve the performance of larvae by providing a wider availability of fatty acids.