"Is it the fresh water that kills them?"
"No," was the reply; "that is one of the most curious features of the life-history of the Pacific salmon. As soon as the fish are nearly ready for spawning, all their digestive parts shrivel up, so that they can't eat. In the male salmon, too, the end of the upper lip turns into a sort of hook so that the fish can't even open his mouth wide enough to eat anything. Then in the fresh water their scales turn slimy and, as they often get injured trying to leap falls and rapids, all sorts of skin diseases attack them. A salmon in the upper reaches of the Columbia headwaters is a pitiful wreck of the magnificent fish that entered it to spawn."
"Do they go far?"
"As much as a thousand miles," was the reply.
"The quinnat and blue back—or the spring and the sockeye, as they are generally known, take the long journeys, but the silver or coho, and the humpback and dog salmon keep to the small streams near the sea. The young fry cannot live in salt water and the instinct of the salmon is to swim up-stream as far as possible, no matter what obstacle is in the way. When they have gone to the very limit, the salmon make pits and holes in the gravel and sand at the bottom of the stream for nests, and drop the eggs in these. The male salmon immediately afterwards floats over the nests and does his share in making sure that the eggs will hatch out."
"How big are the salmon?" asked the boy.
"You'll have a chance to see," the professor answered, as he swung the canoe in to the wharf, at the state hatchery station, "because we're going to measure the ones we tag this morning."
The foreman and one of the men of the station were waiting for them in a good-sized motor boat, towing behind which was a curious-looking affair composed of two small barrels fastened together by long slats.
"Don't you know what that is?" queried the professor, noting Colin's puzzled look.