304 
BULLETIN OF THE BUREAU OF FISHERIES 
CLEAR LAKE 
All Clear Lake specimens were collected with the “new” nets. Tables 76 and 77 
show the average lengths of the different age groups according to the gear by which 
they were captured. Because of differences in growth rate the sexes are treated 
separately. Table 78 and figure 11 present the length frequencies and the average 
lengtn of the catch according to mesh size for the total 1931 and 1932 catch of ciscoes 
from Clear Lake. The Clear Lake data differ from those of the three populations 
just considered in two important respects. First, the relationship that increase in 
size of mesh is correlated with an increase in the average size of the fish taken does not 
hold for Clear Lake as it did in the other three lakes; while the differences in the aver- 
age size of the fish taken in different meshes are great, the larger mesh does not always 
take the larger fish (table 78, fig. 11). Second, in Clear Lake, fish were taken in all 
seven of the sizes of mesh used, and were most abundant in nets that were totally 
ineffective in all the other three populations, that is, nets whose mesh size was greater 
than 2 inches. The circumstance that the largest mesh (3 inches) took the greatest 
number of fish indicates that in making these collections it would have been desirable 
to use additional nets of mesh size greater than 3 inches. There is, however, 
reason to believe that the selection resulting from failure to fish with larger mesh 
nets affects chiefly the relative abundance of the larger fish in the sample. The 
increase in size of mesh from 2 % to 3 inches had little effect on the average length of 
the individuals captured. If this trend were to continue, nets of a mesh size greater 
than 3 inches would be expected to add to the number of large fish without producing 
any important upward extension of the size range of the sample. 
Table 76. — Effect of size of mesh of gill nets on the determination of the average lengths of the age groups 
of the Clear Lake cisco, 1931-32 Collections 
[(Males) Number of specimens in parentheses] 
Size of mesh 
Age group 
Average 
length 
I 
II 
III 
IV 
V 
VI 
VII 
VIII 
IX 
173 (12) 
176 (24) 
190 (2) 
311 (1) 
336 (3) 
212 (16) 
185 (28) 
275 (14) 
296 (35) 
281 (49) 
307 (42) 
236 (3) 
245 (3) 
250 (12) 
256 (25) 
267 (5) 
254 (1) 
291 (4) 
286 (5) 
289 (12) 
291 (18) 
307 (3) 
328 (4) 
338 (2) 
310 (1) 
326 (2) 
328 (2) 
324 (3) 
341 (1) 
347 (3) 
334 (2) 
344 (4) 
2J4 inches. 
2 y 2 inches 
314 (4) 
319 (6) 
324 (4) 
333 (5) 
329 (1) 
334 (6) 
355 (1) 
Average 
176 (38) 
254 (48) 
289 (40) 
318 (15) 
323 (9) 
324 (8) 
334 (15) 
343 (10) 
355 (1) 
Table 77. — Effect of size of mesh of gill nets on the determination of the average lengths of the age groups 
of the Clear Lake cisco, 1931-32 collections 
[(Females) Number of specimens in parentheses] 
Size of mesh 
Age group 
Average 
length 
I 
II 
III 
IV 
V 
VI 
VII 
VIII 
IX 
X 
XI 
1% inches 
1)4 inches 
1% inches 
155 (1) 
179 (5) 
180 (12) 
186 (7) 
201 (1) 
336 (1) 
350 (1) 
357 (1) 
360 (3) 
360 (2) 
351 (7) 
358 (7) 
246 (2) 
245 (8) 
227 (17) 
268 (22) 
316 (29) 
315 (54) 
319 (65) 
351 (1) 
364 (1) 
279 (1) 
263 (7) 
259 (4) 
265 (14) 
260 (14) 
356 (3) 
336 (1) 
351 (9) 
357 (6) 
350 (11) 
301 (1) 
300 (9) 
308 (14) 
310 (15) 
325 (1) 
323 (3) 
332 (5) 
332 (8) 
338 (1) 
376 (1) 
2 inches 
371 (1)1 
342 (4) 
334 (4) 
335 (3) 
347 (4) 
378 (1) 
352 (1) 
379 (1) 
Average-, 
181 (26) 
263 (40) 
307 (39) 
330 (17) 
341 (8) 
342 (9) 
352 (30) 
355 (22) 
360 (3) 
372 (2) 
378 (1) 
