Document Type



Virginia Institute of Marine Science

VIMS Department/Program

Marine Advisory Program (MAP)

Publication Date



Marine Resource Report No. 2019-02


A disease epizootic has developed that threatens one of the most valuable fisheries in the US. The U.S. sea scallop (Placopecten magellanicus) fishery landed $512 million worth of scallop meats in 2017 (NMFS, 2018). This fishery is based on landings of scallop adductor muscles only, with the remainder of the scallop discarded at sea (NEFSC, 2018). During the spring of 2015 both industry and scientific assessment crews noted unprecedented numbers of a parasitic nematode in the adductor muscle of captured scallops (Figure 1). The presence of the parasite in the adductor muscle is expressed through macroscopic lesions, or cysts. These lesions are rust-brown to orange/brown in color with a typically elongated shape, ranging from 2 -12 mm in length and 1 - 4 mm in width. Nearly all lesions were observed along the exterior edge of the adductor muscle between the mantle velar folds of both valves opposite the catch muscle (sweet-meat). This location on the adductor muscle is anatomically adjacent to the kidney-adductor muscle attachment site and opposite of scallop intestine and anus.

Infected scallops were observed in the southern portion of the stock and corresponded with the re-opening of three spatial management areas in this region. The wide distribution of the observed parasite is of concern from a product marketability standpoint and may represent the early stages of an expansion of parasite prevalence and intensity.

Preliminary investigations suggest that the nematode observed is Sulcasaris sulcata (Rudders and Roman, 2018a).


doi: 10.25773/m6xq-nq36


Sea scallop fishery, Sulcascaris sulcata


Award Number: NA16NMF4540043