is limited to the distribution of literature and advice, includ- 

 ing field inspection, for landowners interested in developing 

 a fishery or the fish producing potential of their property. 



In the six most southerly districts, private landownership 

 ranges from 99 per cent in the southwest to 97 per cent in 

 Lake Simcoe district, and 80 per cent and 74 per cent in the 

 disticts of Lindsay and Tweed, respectively. Within this area, 

 a sample survey of owners, with over 50 acres of land, indi- 

 cated 61,929 owners with stream property and 25,503 

 owners with some fishing on their property. These figures 

 show the potential demand for services in the future. 



PROVINCIAL FISHING AREAS 



Provincial Fishing Areas are located at Mount Pleasant, St. 

 Williams, Normandale, Earl Rowe Park, Holiday Beach Park, 

 Pinery Park, Wheatley Park, Cornwall Recreation Area, 

 George Challies Pond (Morrisburg), Inverhuron Park and 

 Hill Lake Hatchery. 



These 11 pond areas are operated under intensive man- 

 agement to provide public fishing for brook trout and rain- 

 bow trout. Most of the areas are near urban centers where 

 opportunities for day-use angling are severely limited. In 

 1970, they had over 70,000 angler visits for 200,000 hours of 

 angling and a catch of 51 ,000 trout. 



During the year, the Department acquired 190 acres on 

 the Plane River in Mulmur Township, Simcoe County, for 



public fisheries development. 



WATER QUALITY STUDIES 



In Ontario, mercury was recognized as a potential pollution 

 problem in the spring of 1970, and an extensive program of 

 fish sampling was begun immediately by the Department in 

 waters known to have received waste mercury from industry. 



Several waters, scattered over the province, contain spe- 

 cies of fish with mercury concentrations well in excess of V2 

 ppm. These problem areas, all associated with mercury dis- 

 charges from chlorine-alkali plants or pulp and paper mills, 

 are portions of the English-Wabigoon-Winnipeg River sys- 

 tem, St. Clair River, Lake St. Clair, Detroit River, eastern Lake 

 Ontario and the St. Lawrence River, and the Ottawa River 

 downstream from Ottawa. 



In addition, many lakes have been found containing fish 

 of some species which are above the V2 ppm level (mostly 

 V2 — 1 ppm). In these waters, no local sources of mercury 

 from human activities are known; mercury deposits in water- 

 sheds or atmospheric fallout are possible sources. 



Extensive testing is being carried out on fish and fish 

 products entering the domestic and export markets to ensure 

 that they comply with quality standards established by 

 health authorities. 



Every effort is being made by many departments of the 

 Ontario Government and the Canadian Government to 

 resolve the mercury problem in Ontario as quickly as pos- 

 sible and maintain the valuable sport and commercial fisher- 

 ies which have been affected. 



Again in 1970, the Department, in co-operation with the 

 Ontario Water Resources Commission, carried out a pro- 

 gram of sampling on bottom organisms, aquatic vegetation, 

 sediments and fish from the Muskoka Lakes watershed to 

 provide baseline data on the levels of pesticides following 

 the widespread use of DDT in these areas over the years. 

 As a result of legislation enacted in 1968, the use of DDT for 

 blackfly and mosquito control in such recreational areas has 

 been prohibited. 



In this age of increasing industrialization, the Department 

 is concerned about the possible effects to fisheries from 

 heated water discharges from several large thermal Gen- 

 erating Stations currently under construction or proposed 

 for sites on the shores of the Great Lakes. 



One such site is on Lake Erie at Nanticoke where a large 

 station is under construction and where a joint study, in- 

 volving Ontario Hydro, Steel Company of Canada, Texaco 

 Canada Ltd., Ontario Water Resources Commission and the 

 Department, is under way to consider the possible effects 

 of these heated discharges. As part of this overall program, 

 the Department will begin a detailed three-year study on 

 the fishery in the spring of 1971. 



NETTING CREWS 



The use of impounding gear (trap nets) is of increasing 

 importance to fisheries workers. With this type of equip- 

 ment, fish can be captured, examined or tagged, and re- 

 turned to the water unharmed. Netting crews, stationed at 

 Maple and Thunder Bay, provide trap nets for the use of 

 District personnel on field projects and help to maintain 

 such gear by repair or replacement. Field personnel are 

 instructed and assisted on netting projects, and some of 

 those, involving exceptionally large nets or difficult sites, 

 are conducted by net section staff. 



The netting crew at Thunder Bay was engaged in ten 

 field projects in northwestern Ontario in 1970. Two projects 

 were of particular significance as they involved a demon- 

 stration of the use of trap nets in the taking of whitefish in 

 the Kenora area and the taking of crappies in the Fort 



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