BULLETIN OF THE UNITED STATES FISH COMMISSION 1885.
SEGREGATION OF THE SEXES OF TROUT.
At or about the spawning season, it is customary for the two sexes of trout to segregate, the males collecting in one large body by themselves, the females doing the same, or, more correctly speaking, I think, being left to do the same, as the herding together seems to be more active on the part of the males. This continues for a considerable time, about the period of the spawning season, and is not the exception, but the rule.
The same is true also of salmon, as is well known among salmon fishermen. It frequently happens that a whole run of salmon for several days will be composed almost entirely of males, the effect of which, of course, is to leave the females together by themselves, whether they take an active part or not in bringing about the separation. In fact, in hauling a seine frequently in a salmon river for some time, it is generally very noticeable that the sexes alternate in coming up the river about the spawning season, a large body of males being followed by a large body of females, and these by a run of males again, and so on through the season.
In the case of the trout mentioned in Mr. Crawford's letter, it is my impression that the males, in accordance with the custom just described, had separated from the females, and had retired to some other part of the lake (or stream), where if Mr. Crawford had fished he would have caught nothing but males. I suppose Professor Brooks would say that the preponderance of females was probably, the result of an exceptionally favorable environment, but I am, nevertheless, very strongly of the opinion that there was the usual number of males in the lake (or stream), though Mr. Urawford did not happen to find them, and that no general preponderance, of females actually existed.
Charlestown, N. H., January 12, 1855.
** Mr. Crawford, in a letter from Stark Water, N. H., January 6, 1885, says: