Survival and growth of juvenile freshwater mussels (Unionidae) in a recirculating aquaculture system

An indoor recirculating aquaculture system was constructed to provide suita ble conditions to culture juvenile freshwater mussels. In the first of thre e growth trials, Villosa iris (I. Lea, 1829) juveniles were cultured for 22 wk, and grew from an initial mean length of 0.4 mm to 2.7 mm. Survival was 26.8% overall. In the second trial, growth and survival were compared betw een juveniles of V. iris held in sediment and without sediment. The initial mean length of both groups was 2.7 mm, and this experiment ran for 17 wk. The juvenile mussels in sediment grew to a mean length of 5.7 mm with 85% s urvival, significantly greater (p < 0.01) than juveniles held without sedim ent (4.5 mm, 74% survival). In the third trial, two cohorts of juvenile Lam psilis fasciola Rafinesque, 1815, increased in length from 1.1 mm and 1.4 m m to 3.3 mm and 4.1 mm, respectively, with comparable survival (78.7% versu s 64.58). Results of these trials demonstrate that juvenile mussels can be reared successfully within recirculating systems. One of the factors deemed important in successful culture is continuous feeding of an appropriate fo od source. In this study, a unialgal culture of Neochloris oleabundans Chan tanachat and Bold, 1962, was used throughout. Regular cleaning of the syste m and water replacement also was important. Finally, the culture of juvenil es in sediment appears to be an important factor in ensuring good growth an d survival. This phenomenon could be related to pedal feeding behavior, pro per orientation of the mussels for filtering efficiency, or stability from physical disturbance.