The monitoring of commercial catches will be important 

 in evaluating the kokanee introduction, splake introduc- 

 tions, and the changes in the fishing resulting from lamprey 

 control measures. 



Captures of planted hybrid splake from introductions of 

 1966-8 indicate that 98 per cent of the 2,000 caught were 

 within ten miles of the planting site. Stomach contents 

 showed that fish were feeding on cottids, smelt and ale- 

 wives. Lamprey scars were numerous from August to No- 

 vember. It was found that splake were spawning in former 

 lake trout spawning beds. The mean length of splake taken 

 was 33.8 cm. 



A shortage of kokanee eggs necessitated a reduction in 

 planting to 20,000. Detailed observations on sex ratios, 

 numbers of fish and temperature were made on several 

 runs. The return of mature kokanee was down from the 

 previous year. Proof of natural reproduction was established. 



A part of this study included a survey of spawning beds, 

 recording gravel size, water and gravel depths, type of 

 substrata, and weed cover area. This data will be useful in 

 determining the suitability of other gravel beds as spawning 

 sites. 



Data collected supported earlier evidence that growth 

 of kokanee in South Bay is slower than in Lake Huron 

 proper. An analysis of fish stomachs was made to see if feed- 

 ing was a factor. 



Data collected from creel census studies predict a con- 

 tinued decline in the smallmouth bass population. There is 

 a positive relationship between warm summers and strong 

 year classes which explains the decline. 



LAKE SUPERIOR UNIT 



This is a new unit, established in 1967 when Ontario ac- 

 cepted responsibility for all fisheries research in Lake 

 Superior. There was extensive co-operation with the 

 Fisheries Research Board in the lake trout rehabilitation 

 assessment program and a lake trout spawning survey. 



GAME FISH UNITS 



LAKE TROUT UNIT 



Creel census information shows a decline in size of fish 



taken, but more fish taken per unit effort of fishing in Lake 



Opeongo. 



Present closing practices do not seem to have resulted in 

 improved angling success as shown by creel census studies 

 on other lakes. 



Studies on the role of food and feeding on the history of 

 the lake trout have indicated that changes in available food 

 have resulted in an accelerated growth rate. 



BROOK TROUT UNIT 



This unit is determining population size and structure over 

 a period of years, monitoring fishing pressure and resultant 

 yield, and assessing reproductive capacity and factors which 

 determine this capacity. 



Preliminary analysis suggests that lack of suitable spawn- 

 ing areas limits production. 



Other studies include the role of hatchery fish in manage- 

 ment of brook trout lakes. Planting methods, use of fish 

 toxicants, bottom fauna, competition from suckers and 

 artificial spawning beds are also being investigated. 



SMALLMOUTH BASS UNIT 



Activities of this unit involve the determination by direct 

 observation of the daily activity patterns and their seasonal 

 changes within various size and age groups. Coincidental 

 with this is the capture and tagging to determine popula- 

 tion estimates. 



WALLEYE UNIT 



This program is also largely based upon direct observation 

 using SCUBA gear and is aimed at assessing environmental 

 conditions preferred by walleye. It has been determined 

 that light is more important in influencing location than is 

 temperature. Shelter, therefore, is important under day- 

 light conditions. Water-level fluctuations also affect distri- 

 bution. 



New and more reliable age determination techniques 

 were assessed. 



A walleye bibliography of 1,600 references has been 

 accumulated and will be published. 



DISCIPLINES UNITS 



LIMNOLOGY UNIT 



This unit is standardizing limnological data collections 

 among fisheries research units and other agencies. 



A small-pond study is aimed at comparing the physical, 

 chemical and biological conditions in a variety of ponds 

 and small lakes in southern Ontario to learn their productiv- 

 ity, actual and potential. 



Studies conducted into gill-net selectivity show that form 

 of the selectivity curve varies with species of fish. 



Changes in the physical and chemical environment of 

 the Laurentian Great Lakes were reported. 



SELECTIVE BREEDING UNIT 



Studies of the life history and ecology of successive genera- 

 tions of splake in natural conditions to determine what 

 to expect of the performance of highly selected splake plant- 

 ing, when made, are being carried out. 



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