SALMON AND TROUT IN ALASKA. 41 



what period the run of king fry occupied, but inasmuch as a few were 

 taken in dayhght, and the total number taken was so Large, it would 

 seem probable that the migration at that time was near its height. 

 No fry of this species were taken in seine hauls made in the river 

 May 22. 



On the lower Sacramento the principal migration of the king fry 

 occurs in March and April. Ice never forms on their breeding grounds, 

 and they are free to travel as soon as they are able, which the tempera- 

 ture of the water and consequent time of hatching make possible at 

 the above date. The adults reach the river in April, May, and June, 

 and in August and September. They spawn in numbers from the 

 middle of August to the end of September, and from the beginning 

 of October until in December. The first eggs deposited begin to 

 hatch about September, and fry begin to migrate about October, 

 or even earlier, and continue throughout the winter, since no 

 obstacle is offered by ice, and the fall and winter rains put the stream 

 into the most favorable condition. The run, is practically over by 

 April 1 on the lower river. From that date on it will be noted that 

 the examples taken gradually increase in size, showing them to be in 

 a manner summer residents.*^ 



In the Karluk the adults first appear about the mouth of the river 

 in May and continue in small numbers into August. They are known 

 to spawn in the river below the lake late in August, or at approximately 

 the same season as in California. The different time of migration of 

 the fry is accounted for by the difference in average water temper- 

 ature. In the Sacramento the eggs are deposited in water of a tem- 

 perature of 56° to 46° F., the winter temperature rarely reaching as 

 low as 40°. In the Karluk the lake surface in August varies between 

 40° and 50°, or slightly above, and as the spawn of this species is 

 deposited in the stream below the lake this may be taken to be the 

 approximate temperature of the spawning beds. It is improbable 

 that any great number enter the lake as adults to spawn in the lake 

 tributaries. At an average temperature of 45° (it is probably less) 

 during August and September eggs deposited in the latter part of 

 August could not hatch before the middle of November. By tliis 

 time it is probable that the temperature has dropped to freezing, and 

 it is doubtful whether even the earliest eggs hatch before the advent 

 of spring. The lake probably clears of ice and the water begins to 

 warm up late in April or early in May. With the increased warmth, 

 due to the long periods of day in that latitude, the fry would have 

 developed at about the date noted, namely, late in June and early 

 in July. As there is little rain at that season, there would seem to 

 be no cause for the downstream movement except age (develo]>ment) 

 and instinct. 



"Rutter, op. oit., p. 93. 



