River, which supports the fishery tor some 40 to 50 miles 

 along the eastern Georgian Bay shore. The tendency for 

 Shavvanaga Basin pickerel to move into off-shore waters 

 shows promise for the rehabilitation of the pickerel stocks 

 in these areas. The importance of this area for fishing neces- 

 sitates the continuance of these valuable monitoring and 

 assessment studies. 



Bark Lake. Fall netting on the spawning beds in Bark Lake 

 resulted in the capture and release of 228 lake trout of which 

 39 had previously been tagged. The remaining 189 were 

 tagged before release. The return of tags by anglers was 

 again encouraged and resulted in 20 recoveries in 1970. No 

 evidence of the 1966 planting of hatchery fish was seen in 

 the fall netting or the anglers' catch. Efforts to determine the 

 average incubation period for lake trout eggs were con- 

 tinued and resulted in an estimate of 107 days. Expressed as 

 a function of temperature, the incubation may be said to 

 represent 591.6 centigrade degree-days. During the period 

 October 15, 1970, to January 25, 1971 (estimated incubation 

 period), the Bark Lake water level was lowered a total of 

 12.9 feet. This long-term project was initiated in 1965 to 

 determine the effect of extensive winter drawdown of water 

 on the natural reproduction of lake trout; it will continue 

 until 1975. 



Lac Seul. Investigations of the effects of water level fluctua- 

 tions on fish production continued in 1970. Spawning areas 

 for northern pike and yellow pickerel were assessed by heli- 

 copter during spring break-up. Species and age compositions 

 were measured by intensive netting operations in conjunc- 

 tion with a sampling program of the commercial harvest. 



PROVINCIAL FISH HATCHERIES 



We have supplemented our rainbow trout brood stocks 

 with a rapid-growing, fall-spawning variety that is not only 

 desirable for the production of catchable fish but is also far 

 more amenable to hatchery culture. Though not yet mature, 

 this new stock will go far in meeting the growing demand 

 from Provincial Fishing Areas. 



Public interest in provincial fish hatcheries is increasing, 

 and the total of visitors to the hatcheries in 1970 was in 

 excess of 94,000. The Chatsworth hatchery accommodated 

 over 15,000 visitors and gave conducted tours for all organ- 

 ized groups. The Normandale hatchery has developed three 

 nature walks and provides a self-guiding, descriptive pam- 

 phlet to augment the visitor's experience. 



Interest in the aquatic environment, and in fish culture in 

 particular, is perhaps a reflection of the publics increased 

 awareness of environmental problems and of their concern 

 for our natural resources. 



The visiting public are welcome at our hatcheries seven 

 days a week. Our conducted tours, of special benefit to 

 school children, afford visitors an opportunity to observe 

 spawning, incubation, and fish rearing procedures. 



Our extension service at present is generally limited to 

 giving advice (and a limited amount of literature) on the 

 development of private hatcheries and aquaria. However, 

 several field trips were made during the year to assist in 

 problem areas. 



Research continues into hatchery fish disease control and 

 eradication, diet refinement, transportation requirements, 

 and techniques for maximizing survival of hatchery fish 

 following release. 



The nutritional requirements of hatchery fish are now met 

 with specially formulated dry diets that replace the ground 

 meats on which hatcheries were once dependent. The new 

 diets have not only increased the productive potential of 

 our hatcheries, but they also have a cost benefit six times 

 that of the meat diets. An additional advantage of the dry 

 diets is that they permit the use of automatic feeders with a 

 subsequent reduction in labour and an improved food 

 conversion. 



In the fall of 1970, the Pembroke hatchery was cleared of 

 fish and completely sterilized in an attempt to rid the station 

 of the lethal Infectious Pancreatic Necrosis (IPN) virus. 

 Though drastic, such action is fully warranted to prevent 

 the further spread of such contagious and lethal disease 

 organisms. 



Our full complement of sixteen hatcheries in thirteen 

 forest districts was operational in 1970. Neither North Bay 

 nor Sandfield reached their full potential because of pend- 

 ing repairs and renovations to facilities. 



An increased commitment of splake yearlings for the re- 

 habilitation of Lake Huron (following the completion of sea 

 lampres' treatment) has resulted in the need for increased 

 hatchery production facilities. For economic reasons, ground 

 water was investigated on Crown lands at the Chatsworth 

 hatchery site. A significant water supply was located, and 

 plans were developed for the Nicholson substation adjacent 

 to Chatsworth hatchery. The productive potential of this 

 new site is expected to approach 800,000 yearling splake 

 annually. 



This program suffered one serious setback when over 300 

 highly selected and mature brood fish were either stolen or 

 destroyed by vandals at both Chatsworth and Tarentorus 

 hatcheries. 



Returns from initial plantings of splake in Lake Huron and 

 Georgian Bay have been gratifying. Angler returns indicate 



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