Aquaculture 2022

February 28 - March 4, 2022

San Diego, California

EVALUATING Schizochytrium sp. AS AN ALTERNATIVE LIPID SOURCE IN FISH-FREE FEEDS FOR SABLEFISH Anoplopoma fimbria

Katherine A. Neylan*, Ronald B. Johnson, Rick Barrows, Scott L. Hamilton, Luke D. Gardner

 

Aquaculture Facility

Moss Landing Marine Laboratories/ San Jose State University

Moss Landing, CA 95039

katherine.neylan@sjsu.edu

 



 Complete replacement of fish  meal  (FM)  and fish oil  (FO)  in  the  diets of  carnivorous  farmed fish  will  likely  be required  to meet  the projected growth of the aquaculture industry in a sustainable way .  A number of viable ingredient s have been found to replace FM,  while suitable alternative s to FO have been  more challenging to identify due to the essential  long-chain omega-3 fatty acids that are missing from terrestrial alternatives. Schizochytrium sp .  is a microalga that is high in docosahexaenoic acid (DHA) , one of the  aforementioned omega-3 fatty acids that are required by fish and important for human nutrition . This study was conducted to determine the effects of microalga-enriched fish-free feeds on sablefish  growth,  condition,  and fatty acid profile .

 A 20-week feed study was conducted in a n outdoor tank array in Moss Landing, CA .  Juvenile sablefish were distributed randomly in to 18 tanks (1000L) with 15 fish per tank (average weight ± SD, 333g ± 2.4g). Six diets were formulated to contain 45% protein and 15% lipid. Diet 1 contained standard levels of FM and FO. Diet 2 contained FO , but no FM.   Diet 3 was completely FM  and FO free, made  with terrestrial ingredients only . Diets 4, 5, and 6  were FM and FO free, and  contained  increasing levels of the microalga,  Schizochytrium  sp. (dried whole cell biomass) , with flax oil making up the remaining lipid requirement. Treatments were assigned randomly to the tanks with three replicate s per treatment.

 Preliminary results suggest that sable fish growth increases with  increasing inclusion of Schizochytrium sp.  and is not significantly different in performance to the control diet containing standard FM/FO concentration.  Fatty acid profiles of the fish fillets indicate that sablefish are able to incorporate DHA from the dried whole-cell  Schizochytrium sp. into their muscle tissue commensurate with DHA inclusion in the diets.