saithe Pollachius virens, a member of the cod family which goes by various other names: coalfish or coley in Britain, and pollock (not the same as pollack) or Boston bluefish in the USA. With a maximum length of 120 cm (48"), this is a substantial fish. However, it is often caught much smaller and in places where it is especially appreciated there are special names for the juvenile sizes; for example, Shetlanders call the smallest sillack or sillock, while the larger year-old specimens are piltock. The species spans the N. Atlantic, descending to New Jersey on the west and the English Channel on the east. The catch on the east side is by far the greater.