THREESPINE STICKLEBACK OF KODIAK ISLAND 



543 



Table 3. — Number of dorsal fin rays on sticklebacks from 

 Karlvk and Bare Lakes 



Table 4. — Number of anal fin rays on sticklebacks from 

 Karluk and Bare Lakes 



Table 5. — Number of pectoral fin rays on sticklebacks from 

 Karluk and Bare Lakes 



The ranges of the counts differ also. For dor- 

 sal rays (table 3) , the fish in Karluk Lake range 

 from 10 to 14 with no individuals having 8 or 9. 

 The Bare Lake counts range from 8 to 12, and 

 no individuals have 13 or 14. For anal rays 

 (table 4), the ranges are 6 to 10, and 6 to 9, for 

 Karluk Lake and Bare Lake, respectively. 



Heuts (1949) shows, for Gasterosteus aculeatus 

 in Europe, a negative correlation between the 

 number of dorsal and anal rays and the water 

 temperature during development of the embryo. 

 The water temperatures at the time of embryo- 



logical development, in Karluk and Bare Lakes, 

 are not known with any degree of accuracy. 



For the sample from both lakes, there is a 

 significant positive correlation between the num- 

 ber of dorsal rays and the number of anal rays 

 in an individual fish. The figures for Karluk 

 Lake are r=0.46, P< 0.005; for Bare Lake, 

 r = 0.22, P<0.005. 



The number of pectoral fin rays is remarkably 

 constant (table 5). Of 800 fins counted (both 

 fins of each of 400 fish), only 48 (6.0 percent) 

 had more or fewer than 10 rays. The data are 

 too few to yield information on correlation be- 

 tween numbers in the left and right pectoral fins. 



Numbers 



Almost every published account of the three- 

 spine stickleback in any location describes it in 

 such terms as abundant, plentiful, or numerous. 

 Low egg counts per female, and the fact that it 

 spawns only once or, at the most, twice during 

 its life, are balanced by a high rate of survival 

 of young and the adaptability of the species to 

 various physical conditions and types of food. 



No quantitative estimates of stickleback popu- 

 lations have been made for Karluk and Bare 

 Lakes. During three summers, a considerable 

 number of fish marked by fin clipping were re- 

 leased in Bare Lake, but recoveries were inade- 

 quate to produce a reliable estimate of population 

 numbers. Nelson and Edmondson (1955) state 

 that the stickleback is the most abundant fish 

 species in Bare Lake, and it may be so in Karluk 

 Lake. Morton, 2 on the basis of fyke net catches, 

 believed the stickleback outnumbered by far the 

 juvenile red and coho salmon in the littoral zone 

 in Karluk Lake. 



Over almost any shoal of either lake, on almost 

 any day in summer, sticklebacks may be seen in 

 widely varying numbers. Usually they are more 

 or less evenly distributed over a considerable area 

 and are not in tightly packed clumps or streams. 

 A single haul with a 70-foot beach seine, sweep- 

 ing some 200 square yards, often catches from 

 300 to 1,500 sticklebacks. Large concentrations 

 have been observed at the mouths of tributaries 



2 The ecology of two Alaskan cliarrs as shown by their para- 

 sites. By William Markham Morton. Master's thesis, Univer- 

 sity of Washington, Seattle. Typewritten, 31 pp., 1042. 



