Page:Popular Science Monthly Volume 64.djvu/52

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48
THE POPULAR SCIENCE MONTHLY.
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

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