Comparison of three culture methods for the intensive culture of northern quahog seed, Mercenaria mercenaria

A number of approaches have been utilized for growing bivalve hatchery seed (1 mm) to a size suitable for field planting (> 8 mm) but few have been di rectly compared, This study evaluated the growth and survival of northern q uahog seed in three different culture systems and two different stocking de nsities. The three systems were: 1) a stacked-tray unit with downward water flow; 2) traditional upweller culture units with water Rowing upward witho ut seed bed expansion; and 3) upweller culture units with water flowing upw ard at fluidization velocities to provide seed bed expansion. The two stock ing densities were 1.0 and 3.0 g whole wet weight clam/cm(2) respectively, During each trial period the seed clams were fed a 1% daily ration (% dry w eight algae per wet weight clam per day) of the cultured diatom Chaetoceros muelleri. After 14 d of culture at the 1.0 g whole wet weight/cm(2) stocki ng density, seed clams (4.4 +/- 0.6 mm initial shell length) under fluidize d-flow condition exhibited better growth (0.54/d), and a greater final shel l length (5.9 +/- 1.0 mm), At the high density stocking conditions, after 2 8 d of culture, seed clams (4.2 +/- 0.6 mm initial shell length) in the flu idized-flow culture conditions again exhibited better growth rate (0.031/d) and a greater final shelf length (6.0 +/- 1.0 mm), The preliminary evaluat ion of fluidized-flow for seed clam culture in land-based nurseries indicat es its potential as a suitable alternative to raceway, downwelling, or trad itional forced-how culture methods.