1933 ANNUAL REPORT, 1932 11 



The application of scientific inquiry to our fisheries and fish cultural problems 

 continues to yield fruitful results, and the following outline of the work 

 accomplished indicates satisfactory progress for the year. 



BIOLOGICAL SURVEYS OF WATERS 



During the period from July 1st to September 30th, five experienced and 

 qualified field biologists were engaged. Three devoted their attention almost 

 exclusively to biological surveys of waters; the fourth to examination and study 

 of hatchery fish for the purpose of preventing, curing or controlling fish diseases, 

 and the fifth to investigations of dams and other obstructions across waterways 

 for the purpose of determining the feasibility of introducing fishways. 



During the summer one hundred and twenty individual surveys were carried 

 out, eleven of which were of a partial character. In the neighbourhood of 

 eighteen hundred and eighty-four individual lakes and streams have been studied 

 to date from the standpoint of their suitability for the growth and reproduction 

 of various species of fish. 



1. Removal of Coarse Fish and Transfers of Fish from 

 One Body of Water to Another 



A great deal of discretion must be exercised in connection with the removal 

 of coarse or predatory fish from any body of water. We must do work of this 

 kind on a scientific basis and not on hearsay depredations of the species com- 

 plained of. In other words, we must have justifiable reasons for the removal 

 of the fish, otherwise it is a waste of time, money and energy, which will have 

 fatal results later, on the natural balance which we are endeavouring to maintain. 



Following up the work of previous years, the removal of predatory pike 

 from the famous trout waters of the Nipigon river and the removal of competitor 

 fish from the waters of Cat or Finger lake, located in the township of Blair, 

 district of Parry Sound, was continued. The purpose of the work in these 

 instances is to increase the natural yield of speckled trout and bass by reducing 

 competitor or predaceous fish in restricted environments. 



A biological survey of Cat lake carried out in 1930 revealed that such a 

 step was warranted. The work involved the removal of adult pike and maskinonge 

 to the French river and the destruction of excessive numbers of turtles with 

 which the lake was populated. Evidence of the depredations of these turtles 

 was not wanting. 



A study of the stomach contents of many hundreds of adult ling taken 

 in lower Rideau lake and Otter lake, located in Lanark and Leeds counties, 

 during the month of January revealed that they subsist on fish. Of one hundred 

 stomachs examined by an assistant field biologist of the Department, ten per 

 cent, contained small-mouthed black bass and the remainder some species 

 of fish as food. It was observed that most of the fish were feeding after they 

 had finished spawning. 



To obtain a better idea of the voracity of ling, the following data are 

 submitted by our field officers and the President of the Smith's Falls Game and 

 Fish Protective Association: 



