liaison capacity for the Department, with the Great Lakes Institute, University 

 of Toronto, which is supported with funds by the Department for its hydrographic 

 work on the Great Lakes; (3) conducting specific limnological research pro- 

 grammes. 



During 1964, a study of the rate of aging in the Bay of Quinte demonstrated 

 the rapid rate at which this water environment is changing. Such changes are 

 of major significance to fisheries and to recreation. 



PARASITOLOGY 



Studies of the parasites of Ontario fishes continued in 1964, with collections 

 from Lakes Ontario, Erie, Huron, Opeongo and Lake of the Woods. Occasional 

 specimens were also submitted from many other waters throughout the province 

 by Departmental staff and by anglers. The number of "firsts" in this work — 

 new host species, new parasites, and new records — continues to impress us with 

 our ignorance of this subject. Much has yet to be learned about the kinds of 

 parasites in important fish species before assessing their effects on fish populations 

 and possibly to developing techniques for reducing the levels of parasitization. 

 It is possible, that some of the parasites identified are capable of causing fish mor- 

 talities of serious economic proportions in waters as large as the Great Lakes. 

 Some parasites, if obvious to the naked eye, reduce the marketability of com- 

 mercial species. 



SELECTIVE BREEDING 



The objective of the selective breeding programme has been to produce a 

 stable, reproductive strain of the hybrid, brook trout-lake trout, which will mature 

 at age three or less, and have the ability of the lake trout to inhabit deep water. 

 Initially, it was necessary to assume that these characters were heritable. We 

 now have proof that this is the case, and are quite certain of being able to produce 

 an acceptably selected hybrid in three or four generations. Progress in the project 

 has been seriously retarded during recent years by inadequate space for the many 

 small lots of selected fish, and for rearing of the selected stock to maturity. The 

 crowding not only results in losses from disease but greatly reduces growth and 

 egg production. When the planned facilities are available we expect to quickly 

 reach our objective and to provide large numbers of selected stock to manage- 

 ment for subsequent planting in Lake Huron. The Great Lakes Fisheries Commis- 

 sion has endorsed the rehabilitation of Lake Huron with splake rather than lake 

 trout. In the event that sea lamprey control is not possible or is economically 

 impractical, splake will be in even greater demand because of their expected 

 ability to maintain themselves in the face of a lamprey population. 



PRODUCTIVITY 



Authority and funds were granted in 1964 to establish a research unit to 

 conduct studies leading to the development of a practical index or indices that 

 might be useful in predicting the fish production of lakes. 



Looking forward to this programme a number of years ago, a series of lakes 

 across the province was selected for appropriate sampling. Samples and measure- 

 ments were taken routinely by District staffs and by Fish and Wildlife and 

 Research head office staffs. Analysis of these data provided the basis of publish- 

 ing in 1964, Section Report (Fisheries) #48 entitled "Chemical characteristics of 

 Ontario lakes with reference to a method for estimating fish production." Two 

 journal papers arising out of this work have also been accepted for publication. 



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