The Canadian Fish Culturist A OeFertmeet of Fisberies Peblicriiu A Bulletin of information and opinion as to Fish Culture in Canada LIBRARY FISHERIES AND OCEANS BIBLIOTHÈQUE PECHES ET OCÉANS MARCH 1950 No. 6 Contents Page The Grayling (Thymallus signifer) in Northern Sask- atchewan-D. S. Rawson . 3 National Park Creel Census-V. E. F. Solman ....... 11 A Population Based on Catch-Effort Statistics- D. N. Omand .................................... 15 Artificial Hybridization of Eastern Brook Trout and Lake Trout-J. E. Stenton ....... ........ ....... 20 Recognition of Trout-Richard B. Miller............ 23 Book Review: Experimental Use of Fertilizer in the Production of Fish-Food Organisms and Fish by Robert C. Ball-Review By M. W. Smith . 26 Requests for earlier issues of the Canadian Fish Culturist continue to be received. A limited number of copies for the issue of May. 1949, remain on hand and distribution will be made on request until the supply runs out. How- ever, no copies of earlier issues are now available. Published under Authority of Hox. R. W. MAYHEw, M.P.. Minister of Fisheries The Canadian Fish Culturist A Department of Fisheries Publication A Bulletin of Information and Opinion as to Fis/t Culture in Canada MARCH 1950 No. 6 3 The Grayling (Thymallus signifer) in Northern Saskatchewan by D. S. Rawson Professor of Biology, University of Saskatchewan, Sa5katoon. The grayling (Thynrallus signifer) is a fine game fish and one of the few in Saskatchewan that can be taken consistently with fly tackle. Since it occurs only in the northern third of the province it has until recently been little known. Varied and conflicting reports have been heard as to its appear- ance, habits and game qualities. Now that air transportation has made accessible many northern waters, anglers are discovering the pleasures of gra}-ling fishing. For these reasons, the Fisheries Branch of the Saskatchewan Department of Natural Resources has undertaken investigations of the game qualities, present distribution and fish culture possibilities of the grayling. Early observations have suggested that its range might be extended southward and tests are now in progress. Distribution GrayNng are found in considerable numbers around the shores of our large northern lakes and in man}- of the tributary streams. From Lake Athabaska we have specimens and records from the north and south shores and especially from the east end. Black Lake and Sullivan Lake, both connecting with the Fond du Lac River near Stony Rapids, are known to have large numbers of grayling. In June, 1949, excellent fly fishing for grayling was found below Woodcock Falls on the Fond du Lac River, 15 miles above Stony Rapids. Specimens from Wollaston Lake have been taken mostlv from the southwest but they are found in the outlet, Fond du Lac River, both above and below Hatchett Lake. They. are present also in the Cochrane and Geikie Rivers and abundant in High Rock Lake, one of the headwaters of the Geikie. Reindeer Lake specimens come from Brochet at the north, Boundary and Tate Islands in the central part and Southend near the outlet. It was in the latter area that large spawning individuals were taken in May 1948 and 1949. The Reindeer Lake grayling are so large that they are often taken in the commercial gill nets of 52'-inch stretched mesh. Cree Lake, about 120 miles west of Reindeer, also contains grayling. The records of grayling from streams south of these four large lakes are difficult to verify. They occur in the Clearwater River which rises in Sask- atchewan and flows northwest to meet the Athabaska at 'Mc.'lurray. Speci- mens have been taken at Preston Lake, near the headwaters of the Clearwater and at Portage La Loche, near the Alberta boundary. There have been persistent rumours of grayling in the Mudjatick River and other streams in 52207-2 4 the northern half of the Churchill drainage but it has not yet been possible to verify these. They are said to be found in Upper Foster Lake which is close to High Rock Lake mentioned above. They are known to occur in the Rein- deer River below the Whitesand dam (nine miles south of Reindeer Lake) but we have no records of grayling taken between this point and the junction with the Churchill River. Thus grayling distribution in Saskatchewan can be said to be wide in the Athabaska drainage, general in the Reindeer Lake area and doubtful in the remainder of the Churchill drainage. It should be noted that Wollaston Lake is centrally located and drains into both the Atha- baska and Reindeer systems. At the present time the outflow to Reindeer Lake through the Cochrane River is about twice that which leaves via the Fond du Lac River. The waters in which grayling now occur appear to be much like those on other parts of the Pre-Cambrian Shield as far south as the Churchill River. It seems reasonable, therefore, to attempt the extension of its range by planting in such places as Lac la Ronge and _amisk Lake (near Flin Flon). Further encouragement may be taken from the fact that a closely related subspecies thrives in Montana. Life History and Rate of Growth The spawning run of grayling was observed at Rocky Falls on the Rein- deer River, about five miles south from the outlet of Reindeer Lake. In 1948, spawning had begun by May 26 and was complete by May 30. In 1949 it began about May 25 and was complete by June 2. At this season Reindeer Lake was still mostly covered by ice and the temperature of the river water at the point of spawning ranged from 7• 0° to 9-5'C. (44.6 to 49.1°F.). Most of the fish in spawning condition were taken in water from three to 10 feet deep, over gravel or rocky bottom, and in relatively quiet areas close to eddies or rapids. They were more abundant just above the rapids than below them. In other locations in northern Saskatchewan, grayling are reported to run into the mouths of small streams for spawning. There are no small streams near Rocky Falls and it is believed that spawning occurs on the rock}- bottom of the main river. Brown (1938a) notes that the grayling in high lakes in Montana usually to a few days and often follows immediately after the ice goes out. The general observation is that stream populations in Montana spawn earlier (April and 'May) and that the spawning period extends over a longer period than, that in lakes. The run of grayling at Rocky Falls in 1948 and 1949 was made up of large individuals. They ranged from 16 inches (fork length), 2•1 pounds to 19•8 inches, 3- 8 pounds. The average was about 17 inches, 2- 8 pounds. Most of these fish were five and six years old with a few four and one seven years. A typical pair of spawning fish, five years old, is shown in the photograph, Figure 1. The male was 18 inches in length and weighed 2 • 5 pounds. The 5 female was of the same length, 18 inches, but distended with eggs and therefore heavier, weighing three pounds. Of special interest is the marked difference in the dorsal fins. That of the male is much longer, extending back to the adi- pose. It is also low in front and high behind. The female dorsal is shorter, about 1-5 inches short of the adipose, and unlike that of the male it is high 4 Figure 1. A pair of spawning gra}•ling from Reindeer Lake, May 24, 1949. Male above 18 inches long 2•5 pounds, female below 18 inches and three pounds. 6 in front and low behind. This sexual dimorphism was found constant in all sexually mature specimens from Reindeer and Wollaston Lakes. It was not evident in immature specimens nor in one male from Lake Athabaska, which was approaching maturity. This difference has not been recorded by Miller (1946) in grayling from Great Bear Lake nor is it mentioned in various papers which the writer has examined, although Jordan and Evermann (1896) say that the dorsal fin is "greatest in males". The geographic distribution of this character should be investigated. I The rate of growth of grayling in Lake Athabaska was determined by Miller (1946) from material supplied by the writer. His analyses resulted in the following average fork lengths, calculated at the end of each year's growth. One year 4- 4 inches Four years 12 • 0 inches Two years 7- 5 inches Five " 13.7 " Three " 10-0 " • Six " 14-8 " Age determinations for 26 grayling from Reindeer Lake show a rate of growth almost identical with that of Athabaska in the first two years but more rapid growth from three to six years. The average length of eight Reindeer Lake specimens five years old was 17 inches, which is two inches longer than the average for Athabaska specimens of the same age. Grayling from Wollas- ton Lake appear to have a growth rate intermediate between those of Reindeer and Athabaska. Great Bear Lake grayling grow more slowly (Miller 1946) and Montana lake grayling (Brown 1943) about the same rate as those from Reindeer Lake. Food and Angling Qualities The food of the grayling has been examined whenever samples could be obtained from northern Saskatchewan. Table I presents the results of analysis of the stomach contents of 26 specimens taken from Athabaska, Wollaston and Reindeer Lakes and from the Fond-du-Lac River. The food materials were removed from the stomachs and preserved in five per cent fornialin for labor- atory analysis.