may have drifted down into the intertidal 

 area and been included in the nneasurements 

 of intertidal spawners. 



Comparisons of Lengths of Pink Salmon from 

 Various Segments of the Run 



Comparisons were made of the lengths of 

 males and fennales from the early and late 

 runs in 1962 to the fresh-water and intertidal 

 spawning areas. In 1963 comparisons were 

 limited to areas in the intertidal zone. 



1962 . --In 1962 the MEHP length was de- 

 termined for 984 adult pink salmon from early 

 and late runs to one fresh-water area (East 

 Fork) and three intertidal areas (main streann 

 of Olsen Creek, Little Creek, and Middle 

 Slough), A nnodification of the graphic method 

 of Dice and Leraas (1936) suggested by 

 Simpson, Roe, and Lewontin (1960) was used 

 to compare the lengths of males and females 

 from early and late runs (fig. 7). The amount 

 of vertical overlap of the black bars (95- 

 percent confidence interval on each side of 

 the mean) indicates a statistical significance. 

 If the black bars are about the same size and 





' I I I I I I I ' I ' I ' I 



FRESH-WATER (EAST FORK), 



T — 1—1 — I I I — I — r 

 N = 60 



INTERTIDAL (MAIN STREAM) 



INTERTIDAL (MIDDLE SLOUGH) 



FRESH-WATER (EAST FORK 

 INTERTIDAL(MAIN STREflM2 

 INTERTIDAL (MIDDLE SLOUGH) 



I 



-L. 



I 



I ■ I ■ I ■ 



' I I I I I I I I I 

 INTERTIDAL (MAIN S TREAM) 



INTERTIDAL (MIDDLE SLOUGH) 



I I I I I I 



INTERTIDAL (LITTLE CREEK 



INTERTIDAL (MAIN STREAM) 



INTERTIDAL(MIDDLE SLOUGH) 



INTERTIDAL (LITTLE CREEK) 



I ■ I ■ ■ ' 



27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 

 MIDEYE-HYPURAL PLATE LENGTH (CM.) 



Figure 7. — Comparison of MEHP length of pink salmon 

 from the early and late runs in one fresh-water area 

 (East Fork) and three intertidal areas (main stream ol 

 Olsen Creek, Little Creek, and Middle Slough), 1962. 

 Horizontal lines represent range in length; black bar indi- 

 cates 95-percent confidence Interval on each side of the 

 mean (vertical line). One-half of the black bar plus the 

 white bar at either end is one standard deviation. N equals 

 the number of specimens in each sample. All except 

 East Fork are in intertidal area. 



do not overlap, the two samples are nearly 

 certain to be significantly different. 



Measurements of males and females from 

 the same areas demonstrate that the lengths 

 of males were more widely dispersed around 

 the mean (fig. 7), as evidenced by ranges and 

 standard deviations. The mean lengths of males 

 and females from the early run in Middle 

 Slough were significantly less than those of 

 other early-run intertidal spawners (t-tests; 

 P < 0.01). 



For males and females (considered sep- 

 arately by sex) the average lengths of late-run 

 fish in Middle Slough and Little Creek in 

 1962 were significantly less than those of 

 late-run fish in the main stream of Olsen 

 Creek (t-tests; P < 0.01 for all except the 

 difference between females from Little Creek 

 and the main stream, which was at P < 0,10). 

 This tendency for fish in the small intertidal 

 creeks. Middle Slough and Little Creek, to be 

 shorter was also noted in the parent year, 

 1960 (Helle et al., 1964). Two possibilities 

 are suggested to account for this size differ- 

 ence: Stocks that are genetically different 

 nnay home to specific portions of the Olsen 

 Creek tideflat, or behavioral patterns may 

 cause segregation of large and small fish. 

 Large adults might find it difficult to spawn 

 in the smaller channels, or large adults might 

 drive small adults away from "preferred" 

 redd locations in the main stream of Olsen 

 Creek. 



The mean lengths of females from the early 

 run in the East Fork were significantly less 

 (P < 0.05) than those of early- run females from 

 the main stream, but the mean lengths of the 

 males fronn the two areas were not significantly 

 different (fig. 7), The mean lengths of males 

 and females in the early run were greater 

 (but not significantly so) than the mean lengths 

 of males and females in the late run from 

 corresponding areas; this relation also held in 

 1960 (Helle et al., 1964). 



1963 . --In 1963 the MEHP length was de- 

 termined for 622 adult pink salmon from the 

 early and late runs to the main stream of 

 Olsen Creek and the late run to Little Creek. 

 Sampling was restricted to these two intertidal 

 areas because the parent year (1961) showed no 

 intraseasonal differences in mean lengths be- 

 tween fish from the main stream and the two 

 forks of Olsen Creek or between those from 

 Middle Slough and Little Creek (Helle et al., 

 1964). 



In 1963 length differences of late- and early- 

 run fish of the same sex were not significant 

 (fig. 8)--in contrast to 1961, when late-run 

 fish were significantly longer than early-run 

 fish. 



Only late-run pink salmon spawned in Little 

 Creek in 1963. Males from Little Creek did 

 not differ in mean length from late spawners 

 in the main stream, but females in Little 



13 



