HATCHERY TECHNOLOGY DEVELOPMENTS TO SUPPORT FARMING NORTHEASTERN US BLUE MUSSELS Mytilus edulis  

Mussel farming regions worldwide are turning to hatchery production to ensure a consistent and high-quality seed supply. The relatively small US West Coast mussel farming industry is almost entirely dependent on hatcheries. New Zealand has spent over $25 million dollars on R&D and now has a purpose-built commercial mussel seed hatchery. Breeding technologies may soon make cultured seed more cost-effective than wild. Blue mussels, Mytilus edulis, are the last species widely under culture in the Northeast for which there is no commercial source of seed. A consortium of research hatcheries in Maine and Massachusetts are now working on developing and refining the hatchery technology for producing mussel seed.

Currently diet studies, using live algae diets and comparing them to alternative diets (freeze-dried algae (Skretting "Ori-one") and Reed Mariculture algae paste), are being conducted at the juvenile post-set stage and during broodstock conditioning. A trend in the initial post-set seed feeding trials suggest that growth rate over 4-5 weeks is the greatest when fed live algal diets (Figure 1), and that both alternative diets produce lesser and similar growth rates. Spawning success also seems to be increased when feeding live diets over alternative diets. Feeding experiments are being conducted monthly with alterations in the amount of alternative diets fed (sometimes in combination with live algal diets) with the aim of improving growth and survival at lower cost than live algae but with similar results. The rate of setting (attachment) and spat retention on different rope substrates in the hatchery with varying diets is also being examined with monthly trials. Initial results suggest that survival over 6 weeks is greatest on the substrates that are fed live algal diets versus the alternative diets (Figure 2). We also in the process of comparing the performance of hatchery-raised seed to that of natural seed. Finally, we plan to compare the performance of the typical blue/black shell phenotype versus a natural shell color morph ("gold") that might be useful to US farmers for marketing and brand identification.