Page:Popular Science Monthly Volume 61.djvu/217

Rh parasitic worms are frequently found in the abdominal cavity. Both sexes lose from 30 to 40 per cent, of their weight.

Such is the condition of the salmon at the time of death. It is not the spawning itself that produces this effect, but the continuation of the spawning efforts after all ova have been extruded and fertilized. Usually there is considerable vitality in both sexes at the time of the complete extrusion and fertilization of the ova, and they have enough energy left, in many cases, to carry them back to the ocean. But they exhibit no inclination to go. Instead, they continue on the spawning beds, persevering in their efforts to spawn and fertilize more eggs. When one fish of a pair dies, the other seeks or is sought by a new mate. Probably the female never notices the death of the male, as there are nearly always several males fighting around each 'nest.' If there happens to be no salmon in the vicinity when one of a pair dies, the

survivor continues his or her efforts alone, futile though they are.

This extreme devotion to a purpose is almost without parallel. There is no instinct whatever to return to salt water. It is even doubtful whether they would revive if taken back. The dog salmon and bump-back salmon spawn in small streams that empty directly into the ocean, and they are found dying and dead in brackish water. The fact that all salmon, of the genus Oncorhynchus, die immediately after spawning once cannot be questioned.