NATURAL HISTORY, TORONTO REGION
in it. Commercially, however, it is of great importance, being always in demand and furnishing an excellent article of food.
29. Brook Trout. Salvelinus fontinalis (Mitch-
ill).—Brook Trout were formerly abundant in all the spring streams near Toronto, but of late years, owing to the pollution of the water and incessant fishing, they have become nearly exterminated. The size attained by this fish depends largely upon its habitat and food. In small streams it may mature at a length of six or eight inches and a weight of only a few ounces, while in large bodies of water, with an abundant food supply, they will reach eighteen inches or more in length and a weight of from six to eight pounds. In the cool days of late autumn the Brook Trout run up to the headwaters of the streams, and there, on the gravelly shallows, deposit their ova ; the spawning season extending from September in the north to December in the south. The number of eggs produced depends upon the age and size of the fish. Yearlings (that is, fish in their second year) will produce from fifty to two hundred and fifty ova, while a large fish may produce as many as fifteen hundred. The eggs are about three-sixteenths of an inch in diameter and of a warm orange colour. The period of hatching depends upon the temperature of the water, ranging from thirty-two days in water at 54° to one hundred and sixty-five days in water at 37°. In the early parts of the summer Trout frequent the ripples and shallower parts of