is an account of the development of the petasmata, 

 thelyca, and appendices masculinae. 



600. Birectilinear Recruitment Curves to Assess 

 Influence of Lake Size on Survival of Sockeye 

 Salmon (OncorliyHcltiix nerka) to Bristol Bay 

 and Forecast Runs. By Ralph P. Silliman. 

 March 1970, iii + 9 pp., 13 figs., 2 tables. 



ABSTR.ACT 

 Comparison of the sizes of latces and the sizes of 

 sockeye salmon runs to Bristol Bay shows that the 

 two variables are closely related. Birectilinear 

 reproduction curves express quantitatively the 

 dependence of small returns on escapement num- 

 bers and of large returns on lake capacity. Com- 

 parison of "hindcasts" from the birectilinear curves 

 with published forecasts for 1961-67 showed that 

 those from the birectilinear curves were closest to 

 the actual returns. This situation changed in 1968- 

 69. A composite of birectilinear return estimates 

 and "probability tree" age allocations is worth con- 

 sidering. 



601. Effect of Flow on Performance and Be- 

 havior of Chinook Salmon in Fishways. By 

 Clark S. Thompson. March 1970, iii + 11 pp., 

 8 figs., 3 tables. 



ABSTRACT 



Adult fall-run chinook slamon {Oiicorhyttchiis 

 tshawytscha) were studied during plunging and 

 streaming conditions of flow in a pool-and-overfall 

 fishway that permitted recycling of fish after each 

 completed circuit. P^lows were controlled by adjust- 

 ment of valves in a lock at the head of the fishway. 

 Individual fish were timed as they ascended a 

 specified number of pools un(ler each condition. 



Combined data on the performance of individual 

 fish and comparisons of combined data from all fish 

 tested suggest that plunging and streaming flows 

 may be equally suitable for the passage of chinook 

 salmon in a pool-and-overfall fishway. .About 60 

 percent of the fish ascended slightly faster in the 

 streaming flow, but the average rate of ascent for 

 all fish was slightly higher in a plunging flow. 



Orientation of the fish is described in relation to 

 type and velocity of flow. Most fish preferred to 

 rest in the lower downstream quadrant of the pool 

 in the plunging flow; conversely, the lower upstream 

 quadrant was preferred in a streaming flow. Resting 

 fish always faced the current. 



602. Biological Characteristics of I ntertidal and 

 Fresh-Water Spawning Pink Salmon at Olsen 

 Creek, Prince William Sound, Alaska, 1962- 

 63. By John H. Helle. May 1970, iii -I- 19 pp., 

 11 figs., 5 tables. 



ABSTRACT 

 Prince William Sound is unique among major 

 pink salmon-producing areas in that a significant 

 portion of the spawning takes place in the inter- 



tidal zones of streams. Olsen Creek is one of the 

 major spawning streams in the sound. 



The percentage of fines (solids passing through 

 an 0.833-mm. sieve) in spawning-bed materials in- 

 creased progressively from higher to lower intertidal 

 levels, i.e., higher intertidal levels contained 

 coarser spawning gravel than lower levels. 



Although less than one-third of the spawning area 

 available in the Olsen Creek drainage is subject to 

 tidal influence, 70 percent of the total pink salmon 

 spawners occupied this area in 196li and 30 percent 

 in 1963. Late-run fish of the even-year line spawned 

 only in the intertidal area; fish of both the early 

 and late runs of the odd-year line spawned in both 

 the intertidal and fresh-water areas. The size of 

 the spawning populations was estimated by a 

 repetitive stream survey technique, which is des- 

 cribed and compared with the three methods used 

 in 1960 and 1961. 



The length of pink salmon was compared between 

 sexes, between spawning areas, and between times 

 of spawning. F'ish in the even-year line that spawned 

 in the small intertidal creeks tended to be smaller 

 than those that used the main stream, but in the 

 odd-year line this difference was confined to females. 

 The mean lengths of females were about the same 

 in 1962 and 1963, but females from the odd-year 

 line were more fecund. In both years a significant 

 positive correlation was shown between lengths 

 of females and numbers of eggs. 



603. Di.stribution and Abundance of F^ish in the 

 Yakima River, Wash., April 1957 to May 

 1958. By Benjamin G. Patten, Richard B. 

 Thompson, and William D. Gronlund. June 

 1970, iii -I- 31 pp., 26 figs., 37 tables. 

 ABSTRACT 

 Fish were collected from the main stem (lower 

 281 km.) of the river at 2-month intervals. Native 

 fish consisted of six families, with 23 species and 

 three hybrids; exotic fish consisted of five families 

 with 10 species. The water temperature from the 

 mouth of the river to 14.5 km. upstream was high 

 in summer compared with the stretch between 

 km. 153 and 281. Eleven species were taken princi- 

 pally from the lower 145 km. of the river; 14 other 

 species were taken mostly from the upper area. 

 The greatest numbers of fish were collected from the 

 mouth to km. 64 and from km. 120 to 177. These 

 abundances coincided with centers of abundance of 

 the families Cyprinidae and Catostomidae. Ontrar- 

 chids were abundant below km. 97. and Cotidae and 

 Salmonidae were most abuntant above km. 161. The 

 fewest fish were collected between km. 72 and 89, 

 possibly because of slow current, high summer 

 temperatures, and a muddy bottom. Seasonal dis- 

 tribution and abundance of each species are dis- 

 cussed. Although cyprinids and catostomids were 

 the most abundant fish, salmon (genus Oiicurhyiicns) 

 and trout (genus Sahno) are the most valuable to 

 man. Trout and juvenile salmon were most common 

 from km. 1.t3 to 281. 



14 



