New feeding strategies for Atlantic halibut and cod larvae to increase the output of high quality juveniles in production systems

The aim of the project is to establish new feeding strategies for halibut and cod larvae in the live-prey stage to improve growth, survival and quality in production systems. The project is based on break-through results in a pilot study where we demonstr ated that by controlling diurnal light and darkness periods together with a meal based feeding regime, incidence of incomplete eye migration was dramatically reduced (from 73% to 15%) in production systems for Atlantic halibut. Incomplete eye migration i s one of the major problems in intensive production of juvenile flatfish. In commercial production these fish are discharged and represent a substantial economic loss and a large welfare problem. The results from the pilot study indicate that with this ne w approach there will be major improvements in production systems for Atlantic halibut juveniles. The project aims to investigate and document effects of various feeding regimes and the frequency of meals to improve digestion, absorption and retention of the prey by controlling larval ingestion by use of light and darkness in cod and halibut. As part of these studies we will determine and establish a dynamic model for gut transit time and retention efficiency for critical nutrients for Atlantic halibut an d cod. Halibut will be our main target species for the studies on eye migration, retinal transformation and appearance of rod photoreceptor cells during metamorphosis