THREESPINE STICKLEBACK OF KODIAK ISLAND 



539 



from below -18° C. in winter to above 29° C. 

 in summer. 



Karluk Lake is drained by Karluk River, 

 which flows some 23 miles and empties into Kar- 

 luk Lagoon, and thence into the ocean. Several 

 small streams plus the drainage of two small 

 lakes, Thumb and O'Malley, flow into Karluk 

 Lake. 



The physical and chemical characteristics of 

 Karluk Lake have been described by Juday et al. 

 (1932). The lake lies at an elevation of 350 feet 

 above sea level. It is 12 miles long; its greatest 

 width is 2 miles, and its area 15 square miles. 

 It has relatively little shoal area, only 10 percent 

 of the total area being less than 30 feet deep. 

 The maximum depth is 410 feet. The beaches are 

 of gravel and rubble, the predominant rock mate- 

 rial being shale. The water is clear, has a pH 

 ranging from 7.0 to 8.7, and is low in carbonate 

 and in total dissolved minerals. It contains an 

 abundance of dissolved oxygen at all depths 

 throughout the summer. 



Bare Lake is only 15 miles from Karluk Lake 

 but belongs to another drainage. It is drained 

 by a small stream, Bare Creek, that flows into 

 Red River. 



Bare Lake is 380 feet above sea level. It is 

 slightly less than 1 mile long; its greatest width 

 is 1,600 feet, and its area about 120 acres. The 

 maximum depth is 25 feet and the mean depth 

 13 feet. The bottom is gravel and rubble on the 

 shoals and soft mud in the deeper area. The 

 chemical characteristics are similar to those of 

 Karluk Lake. 



In both Karluk Lake and Bare Lake, vegeta- 

 tion is sparse. The predominant forms are water 

 moss, Fontinalis; quilhvort, Isoetes; and water 

 buttercup, Ranunculus. There are scattered 

 patches of filamentous algae, and in Karluk Lake 

 there are beds of sparse Potamogeton. 



Juday et al. (1932) have described the plankton 

 of Karluk Lake, and Nelson and Edmondson 

 (1955) that of Bare Lake. Bottom-dwelling ani- 

 mals are few in numbers of species. Diptera 

 larvae, especially of Chironomidae, are abundant 

 in places, and there are larvae of caddis flies 

 (Trichoptera), mayflies (Ephemeroptera), and 

 other insects. Included also are pea clams (Pele- 

 cypoda) and snails (Gastropoda). 



The fishes of Bare Lake consist of seven spe- 



cies: red salmon (Oncorhynchus nerka), coho 

 salmon (Oncorhynchus kisutch), and king sal- 

 mon (Oncorhynchus tshawytscha) ; rainbow or 

 steelhead trout (Salmo gairdnerii), Dolly Var- 

 den charr (Salvelinus malma), threespine stickle- 

 back (Gasterosteus aculeatus), and a fresh- water 

 sculpin (Cottus aleuticus). 



Karluk Lake has, in addition to these species, 

 arctic charr (Salvelinus alpinus) and chum sal- 

 mon (Oncorhynchus keta). Pink salmon (On- 

 corhynchus gorbuscha) spawn in Karluk River 

 and a few enter the lake. Small numbers of the 

 ninespine stickleback (Pungitius pungitius) have 

 been seen in Karluk Lake (Charles E. Walker, 

 private communication, 1956). 



Karluk Lake has been the site of extensive 

 biological investigations. These date back to 

 1889, when Tarleton H. Bean made a reconnais- 

 sance survey of the lake. Various scientists vis- 

 ited Karluk Lake in the years between 1900 and 

 1920. Henry O'Malley and Charles H. Gilbert 

 made a survey of the salmon spawning grounds 

 in 1921. 



In 1926, a party led by Willis H. Rich con- 

 ducted a limnological study of the lake including 

 a physical survey (Juday et al., 1932). Studies 

 of the lake, especially of its red salmon runs, 

 have been carried out on a year-to-year basis 

 since then. 



A weir for counting adult red salmon ascend- 

 ing the Karluk River was installed near the 

 mouth of the river in 1921. It was moved in 

 1942 about 13 miles upriver, and moved again 

 in 1945 to its present location just below the 

 outlet of Karluk Lake. The current investiga- 

 tions include counts and estimates of adult sal- 

 mon entering the lake, of spawning salmon in 

 the tributary streams, and of young salmon leav- 

 ing the lake to go to the ocean. Studies also are 

 being made of certain aspects of the life history 

 of the red salmon and of the limnology of the 

 lake. 



Bare Lake was selected by the Fish and Wild- 

 life Service (Nelson and Edmondson, 1955) for 

 experiments in lake fertilization, because it rep- 

 resents the waters of the area and yet is small 

 enough to be worked on feasibly. Preliminary 

 surveys were conducted in 1949, and each sum- 

 mer, starting with 1950, the lake has been treated 

 with commercial fertilizer. Various limnological 



