Popular Science Monthly/Volume 64/November 1903/The Parent-Stream Theory of the Return of Salmon

by David Starr Jordan

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THE PARENT-STREAM THEORY OF THE RETURN OF SALMON.

By President DAVID STARR JORDAN,

LELAND STANFORD JUNIOR UNIVERSITY.

IT has been generally accepted as unquestioned, by packers and fishermen, that the salmon of the Pacific (king salmon, red salmon, silver salmon, humpback salmon and dog salmon) all return to spawn to the very stream in which they were hatched. As early as 1880, the present writer placed on record his opinion that this theory was unsound. In a general way, most salmon return to the parent stream, because when in the sea the parent stream is the one most easily reached. The channels and runways which directed their course to the sea may influence their return trip in the same fashion. When the salmon is mature, the spawning season approaching, it seeks fresh water. Other things being equal, about the same number will run each year in the same channel. With all this, we find some curious facts. Certain streams will have a run of exceptionally large or exceptionally small red salmon. The time of the run bears some relation to the length of the stream: those who have farthest to go start earliest. The time of running bears also a relation to the temperature of the spawning grounds—where the waters cool off earliest, the fish run soonest.

The supposed evidence in favor of the parent stream theory may be considered under three heads:^[1] (1) Distinctive runs in various streams, (2) return of marked salmon, (3) introduction of salmon into new streams followed by their return.

Under the first head it is often asserted of fishermen that they can distinguish the salmon of different streams. Thus the Lynn Canal red salmon are larger than those in most waters, and it is claimed that those of Chilcoot Inlet are larger than those of the sister streams at Chilcat. The red salmon of Red Fish Bay on Baranof Island (near Sitka) are said to be much smaller than usual, and those of the neighboring Necker Bay are not more than one third the ordinary size. Those of a small, rapid stream near Nass River are more wiry than those of the neighboring large stream. The same claim is made for the different streams of Puget Sound, each one having its characteristic run. In all this there is some truth and perhaps more exaggeration. I noticed that the Chilcoot fish seemed deeper in body than those at Chilcat. The red salmon becomes compressed before spawning, and the Chilcoot fishes having a short run spawn earlier than the Chilcat fishes, which have many miles to go, the water being perhaps warmer at the mouth of the river which flows farthest from the parent ice-fields. The riper fishes run up the shorter river. In Bristol Bay, according to Dr. Gilbert, the great runs ascend sometimes one river, sometimes another. Perhaps some localities may meet the nervous reactions of small fishes while not attracting the large ones. In Necker Bay a few full-grown salmon run besides the little ones. A few dwarf individuals, two and three year olds, ripened prematurely, run in every salmon stream. These little fishes are nearly all males. Mr. H. S. Davis well observes that 'until a constant difference has been demonstrated by a careful examination of large numbers of fish from each stream taken at the same time, but little weight can be attached to arguments of this nature.'

It is doubtless true as a general proposition that nearly all salmon return to the region in which they were spawned. Most of them apparently never go far away from the mouth of the stream or the bay into which it flows. It is true that salmon are occasionally taken well out at sea and it is certain that the red salmon runs of Puget Sound come from outside the Straits of Fuca. There is, however, evidence that most species rarely go so far as that. When seeking shore, they usually reach the original channels.

In 1880, the writer, studying the king salmon of the Columbia, used the following words, which he has not had occasion to change:

It is the prevailing impression that the salmon have some special instinct which leads them to return to spawn in the same spawning grounds where they were originally hatched. We fail to find any evidence of this in the case of the Pacific coast salmon, and we do not believe it to be true. It seems more probable that the young salmon hatched in any river mostly remain in the ocean within a radius of twenty, thirty or forty miles of its mouth. These, in their movement about in the ocean may come into contact with the cold waters of their parent rivers, or perhaps of any other river, at a considerable distance from the shore. In the case of the quinnat and the blueback, their 'instinct' seems to lead them to ascend these fresh waters, and in a majority of cases these waters will be those in which the fishes in question were originally spawned. Later in the season the growth of the reproductive organs leads them to approach the shore and search for fresh waters, and still the chances are that they may find the original stream. But undoubtedly many fall salmon ascend, or try to ascend, streams in which no salmon was ever hatched. In little brooks about Puget Sound, where the water is not three inches deep, are often found dead or dying salmon, which have entered them for the purpose of spawning. It is said of the Russian River and other California rivers, that their mouths, in the time of low water in summer, generally become entirely closed by sand-bars, and that the salmon, in their eagerness to ascend them, frequently fling themselves entirely out of water on the beach. But this does not prove that the salmon are guided by a marvelous geographical instinct which leads them to their parent river in spite of the fact that the river can not be found. The waters of Russian River soak through these sand-bars, and the salmon instinct, we think, leads them merely to search for fresh waters. This matter is much in need of further investigation; at present, however, we find no reason to believe that the salmon enter the Rogue River simply because they were spawned there, or that a salmon hatched in the Clackamas River is more likely, on that account, to return to the Clackamas than to go up the Cowlitz or the Des Chûtes.

Attempts have been made to settle this question by marking the fry. But this is a very difficult matter, indeed. Almost the only structure which can be safely mutilated is the adipose fin, and this is often nipped off by sticklebacks and other meddling fish. The following experiments have been tried, according to Mr. Davis:

In March, 1896, 5,000 king salmon fry were marked by cutting off the adipose fin, then set free in the Clackamas River. Nearly 400 of these marked fish are said to have been taken in the Columbia in 1898 and a few more in 1899. In addition a few were taken in 1898, 1899 and 1900 in the Sacramento River, but in much less numbers than in the Columbia. In the Columbia most were taken at the mouth of the river where most of the fishing was done, but a few were in the original stream, the Clackamas. It is stated that the fry thus set free in the Clackamas came from eggs obtained in the Sacramento—a matter which has, however, no bearing on the present case. In the Kalama hatchery on the Columbia River, Washington, 2,000 fry of the quinnat or king salmon were marked in 1899 by a V-shaped notch in the caudal fin. Numerous fishes thus marked were taken in the lower Columbia in 1901 and 1902. A few were taken at the Kalama hatchery, but some also at the hatcheries on Wind River and Clackamas River. At the hatchery on Chehalis River six or seven were taken, the stream not being a tributary of the Columbia, but flowing into Shoalwater Bay. None were noticed in the Sacramento. The evidence shows that the most who are hatched in a large stream tend to return to it, and that in general, most salmon return to the parent region.

There is no evidence that a salmon hatched in one branch of a river tends to return there rather than to any other. Experiments of Messrs. Rutter and Spaulding in marking adult fish at Karluk would indicate that they roam rather widely about the island before spawning. A spawning fish set free in Karluk River was found three days later at Red River, sixty miles away on the opposite side of Kadiak Island.

The introduction of salmon into new streams may throw some light on this question. In 1897 and 1898, 3,000,000 young king salmon fry were set free in Papermill Creek near Olema, California. This is a small stream flowing into the head of Tomales Bay, and it had never previously had a run of salmon. In 1900, and especially in 1901, large quinnat salmon appeared in considerable numbers in this stream. One specimen weighing about sixteen pounds was sent to the present writer for identification. These fishes certainly returned to the parent stream, although this stream was one not at all fitted for their purpose.

But this may be accounted for by the topography of the Bay. Tomales Bay is a long and narrow channel, about twenty miles long and from one to five in width, isolated from other rivers, and with but one tributary stream. Probably the salmon had not wandered far from it; some may not have left it at all. In any event, a large number certainly came back to the same place.

That the salmon rarely go far away is fairly attested. Schools of king salmon play in Monterey Bay, and others chase the herring about in the channels of southeastern Alaska. A few years since. Captain J. F. Moser, in charge of the Albatross, set gill nets for salmon at various places in the sea off the Oregon and Washington coast, catching none except in the bays.

Mr. Davis gives an account of the liberation of salmon in Chinook River, which flows into the Columbia at Baker's Bay:

It is a small, sluggish stream and has never been frequented by Chinook salmon, although considerable numbers of silver and dog salmon enter it late in the fall. A few years ago the state established a hatchery on this stream, and since 1898 between 1,000,000 and 2,000,000 Chinook fry have been turned out here annually. The fish are taken from the pound-nets in Baker's Bay, towed into the river in crates and then liberated above a dike which prevents their return to the Columbia. When ripe, the salmon ascend to the hatchery, some two or three miles further up the river where they are spawned. The superintendent of the hatchery, Mr. Nic Hansen, informs me that in 1902, during November and December, quite a number of Chinook salmon ascended the Chinook River. About 150 salmon of both sexes were taken in a trap located in the river about four miles from its mouth. At first thought it would appear that these were probably fish which, when fry, had been liberated in the river, but unfortimately there is no proof that this was the case. According to Mr. Hansen, the season of 1902 was remarkable in that the salmon ran inshore in large schools, a thing which they had not done before for years. It is possible that the fish, being forced in close to the shore, came in contact with the current from the Chinook River, which, since the stream is small and sluggish, would not be felt far from shore. Once brought under the influence of the current from the river the salmon would naturally ascend that stream, whether they had been hatched there or not.

The general conclusion, apparently warranted by the facts at hand, is that the Pacific salmon, for the most part, do not go to a great distance from the stream in which they are hatched, that most of them return to the streams of the same region, a majority to the parent stream, but that there is no evidence that they choose the parental spawning grounds in preference to any other, and none that they will prefer an undesirable stream to a favorable one for the reason that they happen to have been hatched in the former.

Mr. John C. Callbreath, of Wrangel, Alaska, has long conducted a very interesting but very costly experiment in this line. About 1890, he established himself in a small stream called Jadgeska on the west coast of Etolin Island, tributary to McHenry Inlet, Clarence Straits. This stream led from a lake, and in it a few thousand red salmon spawned, besides multitudes of silver salmon, dog salmon and humpback salmon. Making a dam across the stream, he helped the red salmon over it, destroying all the inferior kinds which entered the stream. He also established a hatchery for the red salmon, turning loose many thousand fry each year for about twelve years. This was done in the expectation that all the salmon hatched would return to Jadgeska in about four years. By destroying all individuals of other species attempting to run, it was expected that these would become extinct so far as the stream is concerned.

The result of this experiment has been disappointment. After twelve years or more there has been no increase of red salmon in the stream, and no decrease of humpbacks and other humbler forms of salmon. Mr. Callbreath draws the conclusion that salmon run at a much greater age than has been supposed—perhaps at the age of sixteen years, instead of four. A far more probable conclusion is that the salmon set free by him have joined other bands bound for more suitable streams. It is indeed claimed that since the establishment of Callbreath's hatchery on Etolin Island, there has been a notable increase of the salmon run in various streams of Prince of Wales Island on the opposite side of Clarence Straits. But this statement, while largely current among the cannerymen, and not improbable, needs verification.

We shall await with much interest the return of the millions of young salmon hatched in 1902, and turned loose in Naha stream. We may venture the prophecy that while a large percentage will return to Loring, many others will enter Yes Bay, Karta Bay, Moira Sound and other red salmon waters along the line of their return from Dixon Entrance or the open sea.

1. See an excellent article by H. S. Davis in the Pacific Fisherman for July, 1903.