96 SALMON AND TROUT IN ALASKA. 



than females. Dolomi August 4-11 showed a surplus of 21 males 

 in 990; at Quadra August 24-29, 967 examples had an excess of 

 45 males. These figures show an average preponderance of males 

 by 1.3 per cent. There seems to be no difference in the time of 

 arrival of the two sexes. One sex may be more numerous on one day's 

 fishing and the other on the follo^ving day. 



It is stated that in the Fraser during the first of the run, the males 

 are greatly in excess. The presence of unmated males is to a cer- 

 tain extent damaging, since they go through the spawming move- 

 ments alone, and thus disturb the beds. Under wholly natural con- 

 ditions there should be practical equality in numbers of the two 

 sexes. 



PREFERENCES OF THE KING SALMON. 



The king salmon spawns in higher temperatures th&n the sockeye. 

 On the McCloud River it begins spawning at a temperature of about 

 56°, the summer run completing the season within 3° or 4° of that 

 temperature. In Battle Creek the fall run spawns in practically 

 the same range. That they habitually seek a less depressed tem- 

 perature than the socke^^e is shown by their spawning below the 

 lakes into or beyond which the latter species invariably continues. 

 This has been noted at Karluk, on the Wallowa, and on the Salmon 

 and Payette rivers in Idaho, though in short streams like the Yes 

 Ba}' Stream the straggling king salmon may also go above the first 

 lake. But while this temperature is suitable a higher can not be 

 endured. It has been found that the summer run can not be suc- 

 cessfully confined in lower Battle Creek. These fish naturally travel 

 to the cooler upper reaches, and retention in the warmer water of the 

 lower course causes their death. 



At the Trocadero Aquarium it was found that fish of 3 and 4 years 

 can not endure a summer and fall temperature of more than 61°; an 

 addition of 3 or 4 degrees is fatal. Moreover, at that period an 

 abundance of water is essential. This latter condition, perhaps, 

 enables the fish safely to make the ascent of the heated waters of the 

 Sacramento. During ]May, when the height of the summer run is 

 passing, the river temperatures range closely about 60°, at which 

 temperature the fish are able to move at the rate of 10 miles per day. 

 In August, when the fall run is traveling up the river, the temperatures 

 are decreasing from about 80° to 74°. At this temperature they 

 travel but half as fast, though at a more advanced stage of maturity. 

 During October and November the temperatures continue to fall, 

 varying at Sacramento City from 70° to 60°, and 60° to 50° during 

 the respective months. At this time the spawning temperatures of 

 50° to 55° are found in the middle course of the river, and in seasons 

 when the depth of water is suitable it is found that the salmon spawn 

 largely on the shallows below Tehama, thus withdrawing large num- 



