Utilization of waste from a marine recirculating fish culture system as a feed source for the polychaete worm, Nereis virens

Two experiments were conducted to test the effect of feeding the polychaete worm Nereis virens with solid wastes collected from a marine recirculating system. In experiment 1, worms with an initial mean weight of 0.37 g were fed for 80 days with a commercial worm diet (CD), halibut fecal waste (FW), uneaten halibut feed pellets (PW) or a 1:1 mixture of fecal waste and feed pellet waste (MW). The resulting biomass and average weight of harvested worms was significantly higher in the PW group than in the other 3 groups (ANOVA, p<0.05). Total fat levels in the worms from the MW and PW groups were higher than the CD group. In a similar setup for experiment 2, worms with an initial mean weight of 0.18 g were fed varying proportions of waste mixed with commercial worm diet. The CD group was fed only commercial diet, the W100 group fed only waste and two intermediate treatments fed 50% of each (W50) or 75% waste (W75). Total fat content of the worms was significantly higher in the W75 and W100 groups than the CD group. There were no significant differences in terms of biomass or average weight at the end of the experiment. CHN analysis of the remaining substrate after harvest revealed that little in the way of organic content was left behind. Certain fatty acids were abundant in worms from both experiments, specifically 16:0, 16:1, 18:1 omega 9, 18:2 omega 6, 20:5 omega 3 (EPA) and 22:6 omega 6 (DHA) and analysis revealed some treatment differences due to diet. The results demonstrate that production of N. virens using fish wastes is highly efficient. This species is an excellent candidate for integrated aquaculture and waste recycling. (C) 2011 Published by Elsevier B.V.