Reproduction and pathology of blue mussels, Mytilus edulis in an experimental longline in Long Island Sound, Connecticut

An experimental longline was deployed in Long Island Sound, Connecticut to study the biologic feasibility of commercial culture of blue mussels, Mytilus edulis, in the area. Mussels were sampled monthly for 1 year starting 6 months after the seed settled. Samples were processed for histology and studied for gonad development to predict spawning peaks for future seed line deployments. There were 2 spawning peaks; a major one in May and a minor one in August. Gametogenic activity was detected throughout the year with developing gonads present in February and spawning specimens present from April to January. Samples were also examined for pathology to determine if there were diseases or parasites that could affect the operation. Mussels acquired heavy infections of the trematode parasite Proctoeces maculatus (over 60%) in September that lasted to the end of the year. Large areas of the mantle and visceral tissues were replaced with larval and adult parasites. Abscesses were formed with adult trematodes surrounded by massive aggregations of host hemocytes. Mussels reached sexual maturity and commercial size (60 mm) during their first 6 months after seed set. Two opposing forces drove the feasibility of the operation in this atypically southern location for mussel culture; exceptionally rapid growth, but also heavy infections by a trematode parasite enzootic to tropical and temperate waters. We conclude that the biologic potential for a commercial operation exists for a seasonal product that would use the window of opportunity for parasite-free full-grown mussels from the first winter after settlement until the next midsummer.