Nematode Parasitism of Scallops


Category 4 (Negligible Regulatory Significance in Canada)

Common, generally accepted names of the organism or disease agent

Nematode parasitism of oysters, Larval nematode infection.

Scientific name or taxonomic affiliation

Sulcascaris sulcata (family Anisakidae). This nematode in scallops also incorrectly identified as Paranisakis pectinis and possibly as a species of Porrocaecum.

Geographic distribution

Eastern coast of the U.S.A. form Virginia south.

Host species

Larvae reported from Argopecten gibbus, Argopecten irradians, and Pecten sp. as well as from surf clams, Spisula solidissima, the welk, Busycon caniculata, and the moon snail, Lunatia heros. The adult stage of this nematode occurs in loggerhead turtles, Caretta caretta, and the green turtle, Chelonia mydas.

Impact on the host

The larvae of S. sulcata usually occurs in the digestive gland or adductor muscle of scallops. Infection may cause the adductor muscle to take on a brownish colour, due to the presence of the protistan hyperparasite Urosporidium spisuli in the nematode, and the presence of two to four larvae caused sufficient damage to the adductor muscle that the tonicity was lost. However, prevalence is usually low (less than 3%).

Diagnostic techniques

Gross Observations: Possible discolouration of the adductor muscle.

Methods of control

No known methods of prevention or control. However, sea turtles infected with the adult stage of this parasite must occur in the vicinity of the scallops in order to initiate the infection in scallops.


Cheng, T.C. 1978. Larval nematodes parasitic in shellfish. Marine Fisheries Review 40: 39-42.

Citation Information

Bower, S.M. (2001): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Nematode Parasitism of Scallops.

Date last revised: June 2001
Comments to Susan Bower

Date modified: