Nutritional Studies 



The experimental feeding studies initiated at the Dorlon ^rout 

 rearing station, in 195^ were continued. The experiment Involving the use 

 of feeding charts and the feeding of prescribed amounts of food on the basis 

 of the size and weight of the fish, and the mean water temperature, was 

 further expanded this year to include the experimental use and assessment of 

 a pelleted type food as a substitute for the regular mixed diet. 



Initial results from the study have been very favourable. Fish 

 fed on the pelleted food at a 50 to 6o percent level of the prescribed chart 

 rate have been found to have a greater rate of growth at less cost per pound 

 of fish produced than fish fed on the regular mixed diet. The use of pelleted 

 food greatly reduces the amount of time normally required in preparation and 

 the feeding of a mixed diet and no refrigeration is necessary for storage. 

 Pish fed on the pelleted food were also found to be of a more uniform size, 

 requiring less sorting of the stock. The amount of cleaning required in the 

 maintenance of the hatchery ponds is reduced considerably vjlth the elimination 

 of the ground meat in the mixed diet which tends to pollute the ponds and 

 collect on the screens at the outlet of the raceways and ponds. 



Although the current study is still in the experimental stage the 

 use of the pelleted type food would seem to be a valuable innovation to the 

 fish cultural methods presently employed by the Department. The experiment 

 will be continued in 1956 and. If the current results are maintained and 

 the diet is proven to be nutritionally adequate, the pelleted type food will 

 be introduced for use at all the fish rearing stations in Ontario. 

 REGUIATIONS 



Two major changes were made in the Ontario Fishery Regulations 

 during the year. The size limit on yellow pickerel taken by angling was 

 rescinded, and a fall season was provided for the taking of rainbow trout in 

 the Lower Great Lakes, a number of tributary waters, and Lake Simcoe. 



Both amendments were based on the results of intensive investigations 

 and the recommendations of the Department's field staff. The results from 

 numerous lake surveys and age and growth studies carried out on existing 

 pickerel populations scattered throughout the Province demonstrated the 

 general abundance of the species and the overcrowded and stunted condition 



- 61 - 



