XV.—The Life-history and Ecology of the Salmon Gill-Maggot Salmincola salmonea (L.) (Copepod Crustacean)

Abstract

This study was begun in 1936 primarily as an attempt to work out the life-history of the Salmon gill-maggot Salmincola salmonea (L.), a common and widespread copepod parasite of the Atlantic Salmon (Salmo salar). At that time the adult female stage only was known, although this had been reported in Scotland as early as 1766 on a kelt salmon and had been included by Linnæus among his Vermes. It was not, however, until 1939, after three years of field work, that a complete series of the stages in the life-history of the parasite had been collected and the story began to take shape. During this time not only were parasites collected, but a quantity of statistical and observational data was accumulated bearing both on the parasite.and its host. Much of this referred to conditions in the estuary, a part of the common background of the two animals which was soon recognised to be a critical region for both. Consequently special attention was given to parasitised fish from this region, and this led to a widening of the scope of the investigation to include a consideration of the habitats and interrelations of gill-maggot and fish, indicated by the term “ecology” in the title.