|Rawles, Steven - Steve|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2007
Publication Date: 4/1/2008
Citation: Ludwig, G.M., Rawles, S.D., Lochmann, S.E. 2008. Effect of rotifer enrichment with fatty acids on sunshine bass morone chrysops X M. saxatilis larvae growth and survival. Journal of the World Aquaculture Society. 39(2):158-173. Interpretive Summary: Sunshine bass fry must have tiny live food available during their first few days in order to survive. During tank culture of fry to fingerlings live brackish water rotifers (Brachionus plicatilis) are used as their first food. In order to increase the nutritional value, particularly in terms of fatty acids, rotifers are frequently enriched with concentrated fatty acid food enhancements. This study determined sunshine bass fry growth and survival were increased if rotifers that were fed to them were enriched with fatty acids from commercially available products. The rotifers were cultured with an algae paste (Nannochloropsis sp.) alone, the algae paste and Culture Selco®, which is a fatty acid enrichment, or those two products plus another algae paste, Pavlova sp. or an additional fatty acid enrichment (Super Selco®). A comparison also was made between fry that were not fed with those that received rotifers fed Nannochloropsis sp. Only two of the unfed fry survived the eight days of the experiment. For the other comparisons, survival was not different among the treatments. The only differences found were that fry fed rotifers that ate Nannochloropsis sp and Culture Selco® were very slightly longer and heavier. A fatty acid analysis of the rotifer feeds, the rotifers after they ate the feed and the fry after they ate the rotifers showed distinct differences in fatty acids found in the feed, less distinct differences among the rotifers and little differences among the fry that ate the rotifers. Canonical discriminant analysis was used to make that determination. Graphical presentation of that analysis very clearly showed the relationships of differences at the various levels of the food chain. As far as the authors are able to determine, this is the first example of this type of analysis being used to determine these types of relationships in larval fish culture.
Technical Abstract: Sunshine bass Morone chrysops X M. saxatilis culture in tanks starts with feeding the larvae live rotifers. Production might be increased if the rotifers Brachionus plicatilis are enhanced with highly unsaturated fatty acids before being fed to the larvae. The enrichment procedure involves time, effort and cost. This experiment was done to determine if significant differences in survival, growth, and condition resulted from rotifer enrichment. Sunshine bass larvae were cultured in replicated tanks from age 4 days post hatch (dph) through age 12 dph. The following comparisons were made: 1) Unfed larvae were compared to larvae fed rotifers raised on Nannochloropsis paste plus Culture Selco 3000®; 2) Larvae fed rotifers cultured with Nannochloropsis paste compared to larvae fed rotifers cultures with Nannochloropsis paste and Culture Selco 3000®; and, 3) A comparison among larvae fed rotifers cultured with Nannochloropsis paste and Culture Selco 3000® or rotifers cultured with Nannochloropsis paste, Culture Selco 3000® and enriched with Pavlova or rotifers cultured with Nannochloropsis paste, Culture Selco 3000® and further enriched with Super Selco®. No differences in survival were found except in the case of unfed larvae that had practically no survival as compared to survival rates of 55.4% for larvae fed rotifers cultured with Nannochloropsis plus Culture Selco 3000®. Survival in all other treatments varied from 55 to 82%. Larvae fed rotifers cultured with Nannochloropsis plus Culture Selco 3000® had longer standard and total lengths, greater condition and greater weight than those fed rotifers cultured with only Nannochloropsis alga paste. Additional enrichment with Pavlova or Super Selco® did not affect survival, length, growth, or body condition. A canonical analysis of fatty acid contents of rotifer diets, rotifers after ingesting diets, and fry fed those rotifers supported evidence from harvest results. Distances between generated centroids indicated distinct differences among rotifer diets, less distinction among the rotifers eating the diets and little difference among fry ingesting those rotifers. Results suggest that enrichment of rotifers with unsaturated fatty acids does enhance growth, that enrichment may be done during rotifer culture and that additional enrichment beyond that done during culture does not increase survival, growth or condition.