3-10. DETERIORATIVE CONDITIONS OF SCALLOPS AND SHRIMP
a. Dark Gray or Black Scallops. Dark gray or black scallop is a condition that
develops when the scallops are not iced immediately after being caught. (Scallops are
normally shucked at sea with only the adductor muscle being retained, packed in cloth
bags, and then thoroughly iced.) The condition starts as a light grayish discoloration on
the outside surfaces, becoming darker and penetrating inward. Light gray scallops may
be accepted by the inspector.
b. Diseased Scallops. In diseased scallops, small pink nodules, approximately
one-fourth inch in diameter, develop within the adductor muscle. The nodules contain a
pus-like fluid. The condition is not necessarily confined to the surface. The cause of
this condition is unknown. Any lot of scallops with evidence of this disease is rejected.
c. Black Spot in Shrimp. Black spot or "tigering" is a condition caused in
shrimp by enzyme reactions in the presence of oxygen. This black discoloration
develops where the segmented sections of the shell join together. There is a
blackening of the melanin pigments in the shell membranes. This blackening appears
as black bands where the shell segments overlap, giving the tail a banded (zebra or
tiger) appearance. This leaves a tigering appearance. This condition when confined to
the shell is not serious, but when it penetrates into the flesh beneath shell, it is
unacceptable. Aboard fishing vessels, chemicals such as sodium bisulfite are added to
the shrimp when iced to inhibit this development.
d. Fever Shrimp. Fever shrimp is a reddish discoloration of the muscle tissue
under the shell of shrimp and other crustaceans. It is the result of improper chilling
(icing) after the catch. It is more noticeable in white shrimp. The inspector must not
confuse fever shrimp with the normal red membrane that separates the muscle tissue
from the shell.
e. Iodoform Shrimp. Iodoform odor in shrimp is the result of excessive feeding
on certain types of seaweed. There is a strong medicine odor and taste in iodoform
shrimp. It is common for brown shrimp to have an iodoform taste and odor. However, a
pronounced condition is unacceptable as it reduces the palatability for institutional type
In some cases, you may not be able to determine the cause of a deteriorative
condition. You should notify the veterinary officer. The veterinary officer will identify the
deteriorative condition or he may have you prepare a sample for submission to the
medical laboratory. For further information, see subcourse MD0704, Inspection
Records and Reports.