|dc.description.abstract||Since the middle of the last century, a considerable amount of scientific literature has been published on the so called “glacial marine relicts,” Mysis oculata var. relicta Lovan and Pontoporeia affinis Lindstrom. Intensive and extensive studies have been made of the ecology, natural history and distribution of these and similar forms, mostly with the object of establishing their relict nature. The discovery of these forms in a number of North American lakes has thrown considerable doubt on the validity of several of the theories of origin which have been postulated. At the same time, it has been recognized, that in the large and extremely oligotrophic lakes of North America, these forms are important elements in the food of such commercially important species as the whitefish, Coregonus clupeaformis, the ciscoes, Leucichthys spp. and the lake trout, Cristivomer namaycush.
When the Fisheries Research Board undertook the investigation of the large lakes of the Canadian Northwest, a large amount of material for the study of these two forms was made available. Under the direction of Dr. D.S. Rawson, surveys on Great Slave Lake were conducted in the summers of 1944 and 1945, and on Lake Athabaska in 1945. The writer was a member of the Great Slave survey party in 1944, and of the Lake Athabasca party in 1945. Dr. R.B. Miller directed a survey of Great Bear Lake in 1945. Data from these surveys, together with data obtained by Dr. D. S. Rawson from a few other North American lakes, formed a substantial body of research material which served as a basis for this study.
The purpose of this study, therefore, has been to investigate the ecology, biology and economic importance of Pontoporeia and Mysis in those lakes from which material was obtained, with particular reference to Great Slave Lake and Lake Athabasca. The records of distribution of Pontoporeia and Mysis in these lakes were not available to European workers, who published their scientific work in the early part of the century. For this reason the writer has also attempted to re-evaluate some of the theories of origin, concerning these species, which have been proposed by various European workers.||en_US