ALASKA FISHERY AND FUR-SEAL INDUSTRIES, 1924 107 



Last fall the water of the lakes reached its lowest level on September 5, which 

 was during the height of the salmon spawning period, after which it rose steadily 

 until on October 21 it was 18 inches higher. As the height of the spawning 

 period was during the lowest stages of the lakes, and as the shallowest nest 

 located during that time was covered with 12 inches of water, few spawning 

 areas were covered with less than 30 inches of water at the time of the freeze-up. 



On January 3 the level of the lakes had fallen 26 inches below the level of 

 October 21 and 8 inches below the level of September 5. The position of the 

 ice along the shore did not indicate that the level of the lakes fell after the freeze- 

 up, but this is believed to be the case. During the months of January and Feb- 

 ruarj^ there was no change in the level of the lakes but a great increase in the 

 thickness of the ice that covered the lakes, especially during January. 



On January 3 the average thickness of the lake ice was 12 inches, and it in- 

 creased rapidly to 30 inches during the cold weather of that month. During 

 February the increase was slow, and on February 24 the average thickness was 

 36 inches. There was no difference in the ice on Aleknagik and Nerka Lakes. 



Upon first reaching Aleknagik Lake and finding the low level of the lake and 

 the thickness of the ice it was believed that spawning nests in shallow lake-shore 

 areas would be frozen, but this was found not to be the case. All of the nests 

 marked last fall were relocated and found to be centered in what are known 

 in this district as "hot holes." Many of these "hot holes," most of which are 

 located along the shores of the lakes, remained open during the coldest periods. 

 Others formed a thin sheet of ice that increased in thickness as the water became 

 deeper away from shore. All "hot holes" observed opened up promptly during 

 periods of moderate weather. In travehng along the shores of the lakes it was 

 noticed that important spawning areas observed last fall during the salmon 

 spawning period were centered in "hot holes." 



Tributaries of Aleknagik and Nerka Lakes that could be reached were examined 

 to determine the effect of the winter cold on their flow, to ascertain their tempera- 

 ture, and to locate Dolly Vardens. With the exception of Little Togiak River, 

 Creeks Nos. 11 and 27, and Lynx Creek, conditions in all tributaries examined 

 were identical. All were laid over with from 6 to 12 inches of ice, which in turn 

 was covered with many feet of snow. They were discharging approximately one- 

 half the amount of water that they did last fall, and their temperature was 32° F. 

 Little Togiak River was open in mid-channel and discharging only slightly less 

 water than last fall. Its temperature was 32° F. Creeks Nos. 11 and 27 were 

 dry or entirely frozen up. Lynx Creek was open throughout most of its length, 

 being covered with ice only in reaches where the current is slow. Lynx Creek 

 was discharging about two-thirds the amount of water that it did last fall, and 

 its temperature was 32.5° F. 



WATER TEMPERATURES 



The temperature of the lake water was taken in many places, at various depths, 

 and at different times when the temperature of the air ranged from 38 to 42° 

 below zero. Immediately under the ice the temperature of the water was at all 

 times 32° F. When the glass was lowered to a depth of 25 feet or more a slight 

 rise in temperature was noticed. The highest water temperature found was in a 

 group of "hot holes" on the east shore of lower Nerka Lake, which maintained a 

 constant temperature of 35° on the bottom, the water at the surface being colder 

 in proportion to the depth of the "hot hole" and the air temperature. 



WORK ON PREDATORY FISH 



Work on Dolly Varden trout was made difficult by the depth of ice and snow 

 that covered the lakes and streams. This condition prevented the intelligent 

 use of nets, as the fish could not be located. Camps were chosen with reference to 

 favorable locations for trout, and many holes were cut through the ice but no 

 concentration of trout was found. Fishing was carried on through these holes 

 with hand lines at all available times, but with meager results. Only 56 trout 

 were taken. 



We feel that the failure in this part of the work was due largely to lack of ex- 

 perience with winter conditions. Last October at the close of the fall work 

 P. Knutsen, who spent the winter trapping at the head of Aleknagik Lake, was 

 furnished two trout gill nets to be used for Dolly Vardens. With these two nets 

 and one of his own Mr. Knutsen took 1,300 Dolly Vardens at the liea ; of Aleknagik 

 Lake after our departure. They were taken just before and after the freeze-up, 



