| WEANING FROM LIVE TO FORMULATED FEED IN INTENSIVE CULTURE OF THE BALLAN WRASSE |
| OPSTAD, INGEGJERD1, Katerina Kousoulaki2 and Anne Berit Skiftesvik1
1 Institute of Marine Research, Nordnesgaten 50, N-5817 Bergen, Norway
2 Nofima AS, Kjerreidviken 16, N-5141 Fyllingsdalen, Norway. E-mail: ingegjerdo@imr.no |
| Salmon lice infections have become a more intense issue for salmon farmers as they increase in magnitude and persistence. The latter point is of particular concern as some recent lice outbreaks appear to be resistant to chemical treatment. This has led to rapidly increasing interest in using cleanerfish as a primary solution to combat sea lice infections. One of the species of interest in this regard is the Ballan wrasse (Labrus bergylta), which is tolerant of winter sea temperatures and more effective for delousing larger salmon in comparison of other wrasse species. However, the expected demand for these fish in the near future is impossible to meet with wild catches without severe overfishing. Major bottlenecks in the production of ballan wrasse are weaning the wrasse from live to formulated feed and slow growth rate. Ballan wrasse larvae weaning success appears to be dependent on the presence in the weaning diets of specific raw materials, probably related to crustaceans, such as shrimp or krill. The quality of these raw materials, as well as the feed processing method, influence weaning success. In order to evaluate the effect of diet on weaning success, eight experimental diets were tested with tree replicates in each group. The diets contained three levels of ethoxyquin, two levels of protein quality and two types of attractant. Significantly higher weight was obtained in the groups fed with fish meal as the protein source and krill hydrolysate or shrimp meal as attractants. However, the highest survival was found in the groups fed with feed made of cod fillet combined with either shrimp or krill hydrolysate. The dietary ethoxyquin levels had a significant negative effect both on larval growth and survival during weaning. |
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