6 THE REPORT UPON No. 9 



A study of the probable destruction of lake trout spawn by ling was carried 

 out on Silver Lake, South Sherbrooke, Lanark County. Following is a quotation 

 from a report submitted on this subject: — 



"A string of gill nets was set at various places in the lake to determine the spawning grounds 

 of the trout. When these were found, nets were set over and in the vicinity of them throughout 

 the period. Other settings at various places in the lake were made to determine the movements, 

 if any, of the fish during this time. 



The results of the settings would seem to show that the order of abundance of the fish in 

 this lake is as follows: Lake trout, pike, suckers, ling, rock bass. However, the lake trout figures 

 were obtained when they were on the spawning grounds. Approximately eighty per cent. (80%) 

 of the trout caught was liberated carefully and in good condition at the time of lifting. 



"Sixteen ling in all were obtained from fourteen gill net settings, as compared with 77 trout, 

 36 pike, 30 suckers, 13 black bass. It would appear, therefore, that the ling are not .far in excess 

 of the other fish in this lake. 



"A careful analysis of the stomach contents of these ling revealed no fish eggs of any kind. 

 However, it did show that eighty-five (85%) per cent, of the stomach contents of the ling consisted 

 of fish and fish remains; of which thirty-four per cent. (34%) of the identifiable material was 

 ciscoes. Thus, they comjjete with the lake trout for food. Of the remainder of the stomach 

 contents, fourteen per cent. (14%) consisted of one of the varieties of whitefish food. 



"Analyses of ling stomachs from several other points in Ontario have also been made — 

 thirty-eight in all — twenty-six of which came from Lake Nipigon. The summary of these would 

 indicate that approximately ninety per cent. (90%) of the stomach contents was of fish origin. 

 A large percentage of this was ciscoes. Many cisco eggs were present, liberated in the digestive 

 processes, probably from the ciscoes eaten. I'he only other eggs found were, three whitefish eggs. 



"Because of the few specimens caught in Silver Lake, it is suggested that an effort be made 

 to secure more specimens of ling during the spawning period of 1928, in order that a more complete 

 report may be made." 



Investigations were conducted on the Scugog River below Lindsay; the 

 Thames River below Chatham ; Sydenham River below Wallaceburg and Sixteen- 

 mile Creek below Milton, as a result of specific complaints in regard to objection- 

 able stream pollution. Corrective measures were suggested in order to control 

 tlie various trade wastes entering the waters in question. 



Fig. 2. — Scale taken from white- 

 fish (Coregonus clupeaformis- 

 Mitchill), reared at Glenora 

 Hatchery. Age, one year. 

 One winter band indicated. 



Investigations were made on that portion of Newboro Lake known as 

 "The Bog," and recommendations made in regard to setting it aside as a Game 

 and Fish Preserve. 



The muskrat situation, along the Severn River, was studied and it was 

 recommended that a constant water level be maintained, by allowing more 

 water to escape at periods of high water and less during periods of drought. 



Outstanding work in fish culture was carried on with whitefish and 

 maskinonge. The manager of the Glenora Hatchery, after much persistent 

 endeavour and experimentation with artificial feeding, has succeeded in rearing 

 whitefish in the hatchery up to three years of age. Some first year specimens 



