tion becomes widely dispersed after the spawning period. 

 Data on growth rates and sexual maturity showed little 

 change from last year. Creel census studies revealed that 

 angler success improved considerably in the Moon River 

 area but declined slightly in the Shawanaga basin. 



Examination of 65 tag returns from the Shawanaga area 

 indicate that this population is now travelling farther afield 

 after spawning. Over 75 per cent of the fish, which were 

 tagged close to shore, had moved to off-shore waters and 

 were occupying niches that were formerly inhabited by 

 discrete off-shore populations only. 



Commercial landings of pickerel decreased from 32,369 

 pounds in 1968 to 23,483 pounds in 1969. The largest de- 

 crease was in the northerly part of Georgian Bay and was 

 partially offset by increases in other areas. A tenfold in- 

 crease was experienced in the Shawanaga-Croundhog area 

 and was due principally to the migration of fish from 

 Shawanaga to Groundhog and the entrance of the 1965 

 year class to the fishery. 



It is anticipated that these studies on yellow pickerel will 

 be continued indefinitely. 



Bark Lake. An intensive creel census study was conducted 

 on Bark Lake, Renfrew County, during the summer of 1969, 

 and on Aylen Lake which is being used as a control area for 

 comparative purposes. A slight decline in angling success 

 relative to lake trout was observed on both lakes when com- 

 pared with the results of a similar survey in 1966. It was also 

 noted that the average size of lake trout in the anglers' 

 catch from Bark Lake increased slightly (3.1 to 3.6 lbs.) 

 whereas the average size from Aylen Lake declined from 

 2.7 to 2.4 lbs. 



Fall netting on the Bark Lake lake trout spawning beds 

 was continued and resulted in the tagging and release of 

 147 lake trout. The return of tags by anglers from pre- 

 viously marked fish was encouraged, and 13 tags were 

 received in 1969. Efforts to determine the average incubation 

 period for lake trout eggs were continued and resulted in a 

 figure of 145 days. Since the natural incubation period is so 

 variable (55 days in 1968-9 and 145 days in 1969-70) and 

 appears to relate directly to water temperature, it is prob- 

 ably more desirable to describe incubation in terms of 

 degree days. 



During the period October 17, 1969, to March 11, 1970 

 (incubation period), the Bark Lake water level was lowered 

 a total of 28.61 feet. 



This long-term project was initiated in 1965 to determine 

 the effect of the extensive winter drawdown of water on 



the natural reproduction of lake trout and will continue 

 until 1975. 



Lac SeuL Since construction of a dam in 1929, this large lake 

 of 500 square miles in Sioux Lookout Forest District has 

 experienced annual fluctuations of water levels between 14 

 and 16 feet. During 1969, a biologist and summer students 

 continued the assessment of the effects of these fluctuations 

 on fish production. Depth-sounding of the lake basin was 

 completed, and assessment of water quality continued. Scale 

 samples from 1,500 yellow pickerel and 1,500 northern pike, 

 collected in gill and trap nets, will be used to relate age 

 distribution with water fluctuations. As well, test netting 

 was used to assess the species composition in the reservoir. 

 Investigations were initiated in tributory lake systems for 

 supplementary information on sub-populations of fish and 

 their contribution to production in Lac Seul. The program 

 will continue in 1970. 



PROVINCIAL FISH HATCHERIES 



The potential for fish culture in the fields of protein pro- 

 duction and recreational fishing has resulted in the develop- 

 ment of a specialized technology. Fish culture has been 

 practised for centuries but with varying degrees of success. 

 New discoveries and techniques have had to evolve in the 

 face of resistance from the old traditional practices. 



Early provincial fish hatcheries concentrated on mass pro- 

 duction of commercial species with little or no concern 

 given to biological and environmental requirements. In 

 general, the purpose of culture should be to assist rather 

 than replace nature. Early fish culturists held the opposite 

 view. 



With better understanding of the requirements of hatch- 

 ery fish for maximum growth and survival, we ace now in a 

 better position to justify the hatchery as an economical and 

 practical tool of fisheries management. 



The basic aim of our hatcheries today is the economic 

 production of high-quality species to sustain and develop 

 recreational fishing throughout the province. Our interests 

 lie in maximizing the returns of hatchery fish to the an- 

 gler, taking advantage of natural reproduction and growth 

 afforded by releases into suitable natural waters. 



Research is being conducted on the improvement of 

 transportation and planting techniques to ensure maximum 

 survival and returns to the angler. This includes the use of 

 helicopters on small inland bodies of water. Our program 

 of marking all hatchery fish by the removal of a single fin 



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