The Inconnu (Stenodus leucichthys mackenziei) in Great Slave Lake and Adjoining Waters

Material for this study was gathered by field parties of the Fisheries Research Board in the summers of 1944, 1945 and 1946. A description of the subspecies is given, based on measurements of 26 specimens. The distribution of Stenodus in Great Slave Lake, and in northern North America is outlined. The rate of growth was determined from an examination of scale samples from 298 fish, and it was found that the inconnu has a rapid growth rate, even in this highly oligotrophic lake. Inconnu spawn mainly in the rivers which enter Great Slave Lake from the Mackenzie Lowlands. The upstream run apparently occupies most of the summer but evidence is presented which indicates a major movement in late August. The post-spawning, downstream run takes place in late September or early October. Residents take advantage of it to put up inconnu for winter dog feed. The food of young inconnu in the spawning streams was found to be mainly invertebrates, whereas in Great Slave Lake the species is almost entirely piscivorous. A list of parasites is given, among which Triaenophorus crassus is considered of major importance. The rate of infestation with the larvae of this worm is high—88 per cent of 49 fish examined, at a rate of 64 cysts per 100 pounds. At present the major use of the inconnu is in the domestic fishery where it serves local trappers, and others, as dog feed.