National Geographic : 1968 Aug
National Geographic, August, 1968 question I am asked most often about the salmon's life story. Somehow people find es pecially poignant the thought that the reward for the intense physical struggle of the spawn ing journey is certain death. The tower in Brooks River rang metallical ly as Will and George and I climbed to our perch. Beneath us salmon spread almost uni formly over the stream bed. Everywhere fish dashed about, protecting their terri tories, digging nests, spawning. River edges and shallow bars became the graveyards of spawned-out fish, their duty to the race done, their lives ended. I watched salmon below me turn suddenly on their sides and slap the gravel bottom with powerful tails. Sand, pebbles, and larger stones were dislodged and carried down stream by the river's swift current. The result was a hollow-a nest, or redd, in which the female would lay eggs (page 200). "There's a good battle!" George exclaimed, as a sudden flurry drew our attention to a nest at the base of the tower. Protecting his territory, the male dashed at an intruder, snapping with the hooked snout and fierce teeth that had transformed his jaws during the spawning journey (right). For a moment the two fish rolled over and over together, then dashed from the nest a few feet before breaking off the encounter. Another pair of males tangled briefly, then sidled crossways downstream in a ritualized bluff-as if daring each other to start the fracas anew. Camera Captures a Rare Sight Despite interruptions for such jousting, the redd is built and spawning occurs. Unless an observer knows what to look for, though, he may miss the actual spawning act. Even many veteran field biologists have never seen it; thus NATIONAL GEOGRAPHIC photogra pher Robert F. Sisson's pictures represent a remarkable achievement (pages 201-202). The female salmon settles to the bottom of the nest, and the male takes a position beside and a little to the rear of her. Suddenly both fish begin to vibrate rapidly, and thrust them selves forward in the redd. When eggs and milt are released simultaneously, about 98 percent of the female's eggs are fertilized and settle to the bottom. After the spawning act, the female moves upstream and digs another egg pit, where the pair spawns again. Meanwhile, gravel carried downstream covers the first group of eggs. A female may spawn in five or more egg pits occasionally with different males. The river's unremitting current smooths the gravel bottom. New waves of salmon move in to dig and spawn and die. The eggs lie for many weeks under as much as 16 inches of gravel. Eventually the dark spots that are eyes shine through the trans parent shells. Late in this "eyed-egg" stage the unborn little fish can be seen wriggling around, preparing to burst forth. Some time in the winter the eggs hatch. The alevin, as fisheries men call the hatchling that emerges, is an ungainly creature, with a massive orange-colored yolk sac attached to its underside. The sac supplies food for the little fish while it waits in the gravel, devel oping (page 203). Then on a dark night it Hooked jaws of a male sockeye can be as fearsome as they look; males may seize rival suitors by the tail and shake with bulldog ferocity during fights at mating time. Males develop misshapen jaws on the spawning run from the ocean, while females swell with eggs. Stomachs shrink as both sexes shun food, living on stored fat. Traffic jam of the homeward-bound builds up in the lower Adams River. Late arrivals must actually wait turns for breeding space. Studies of the 305-acre spawning ground re veal that in a recent bumper year it produced a sockeye catch retailing for $30,000,000.