Disease Presence and Prevalence
Sea scallops can become infected with various diseases and parasites. From a fishery perspective, these diseases and parasites may affect meat quality, yield, and survival. The prevalence, intensity, and spatial extent of two diseases are routinely monitored by the VIMS Sea Scallop Research Program.
In the Mid-Atlantic region, prominent blister-like growths have been observed in adult scallops. These blisters are secreted by scallops as a form of self-protection when organisms, typically worms, attempt to bore through their shell. The blisters have several stages, with early stages exhibiting a thin, discolored layer of proteins called conchiolin and advanced stages becoming a hard, raised mound filled with mucus. Using survey data, we found that scallops with advanced blisters had significantly lower meat weights than those with less severe blisters and that blisters were more likely to occur in larger scallops and in deeper water.
Since 2015, the nematode Sulcascaris sulcata has been infecting sea scallop adductor muscles in the Mid-Atlantic region. Infections are expressed as orange, rust, or brown lesions in the adductor muscle also referred to as the scallop meat.
The VIMS Sea Scallop Research Program has an interest in understanding the parasite ecology and the spatial distribution of infected scallops, with monitoring occurring as part of several projects since 2015. Infections are observed annually during resource surveys and quarterly during two different projects:
- An Investigation into the Scallop Parasite Outbreak on the Mid-Atlantic Shelf: Transmission Pathways, Spatio-Temporal Variation of Infection and Consequences to Marketability
- The Effect of Density on Growth, Yield, and Reproduction of the Sea Scallop, Placopecten magellanicus
Sea scallops infected with nematodes have been documented in the Mid-Atlantic Bight area of the resource but not in the Georges Bank resource sub-unit. The majority of infected sea scallops have been observed south of New Jersey. The spatial extent of infections has varied from year to year, with both northward expansions and contractions observed over the course of study.