Hatchery protocols for production of blue mussel seeds

Mytilus edulis, commonly known as the blue mussel, is the second most economically important mussel cultivated in Europe. Faced with increasing spatial limitations inshore, researchers and industry are looking at distant offshore sites for longline cultivation with potential failure and lack of recruitment. Presently, low, inconsistent seed availability and suboptimal systems not adapted to exposed conditions present obstacles for successful expansion. Hatchery production of blue mussel seeds could be a solution to ensure reliable supply and introduce opportunities for selective breeding and triploid production. However, due to the low cost of natural spat and final sale value of mussels, it remains underdeveloped. To overcome the prohibitively expensive cost of hatchery reared spat, optimisation is necessary.

The extant Irish protocol for blue mussel hatchery seed production developed within AquaVitae, the Atlantic research consortium for sustainable aquaculture, is not operational for mussel farmers without a traditional shellfish hatchery. This report aims to report an adaptation of this protocol that requires less technology, and labour. Mytilus edulis larvae were grown under two rearing systems in Denmark, the first in specialised conical tanks optimised for larval rearing and the second, in large square tanks that have not been tested before. This protocol details the processes starting from broodstock conditioning and spawning to larval rearing, and finally, to larval settlement and the production of spat. The report demonstrates that the high technological protocol developed in Ireland could be adapted to require less labour through a flow-through water change system and a cheaper, low- technological method developed in Denmark could be a viable alternative.