higher than survival in fresh-water areas. 

 Their study also showed that the salinity of 

 the water in the gravel at redd depth was 

 dependent on the salinity of the water covering 

 the area. This saline water in the gravel was 

 thoroughly flushed out by fresh water as the 

 tide ebbed. 



Rockwell (1956) demonstrated in laboratory 

 experiments with pink salmon that at salinity 

 concentrations up to 18 parts per thousand 

 (°/oo) fertilization was not inhibited, and that 

 even at 30°/oo some fertilization could take 

 place. He also showed that better growth, 

 survival, and activity were attained by larvae 

 in dilute sea water as opposed to those in 

 fresh water. At Herman Creek in Southeastern 

 Alaska, Rockwell found survival of pink salnnon 

 to the eyed egg stage higher in some inter- 

 tidal areas than in upstream areas. 



Pink salmon mature at 2 years of age, with 

 rare exceptions (Anas, 1959). Adults spawn 

 in streams in the summer or fall and like 

 all Pacific salmons ( Oncorhynchus spp.) die 

 shortly after spawning. The resultant fry 

 emerge from the gravel after absorbing the 

 yolk sac and migrate directly to sea. They 

 return as adults after about 1 year in salt 

 water. Because of their strict adherence to a 

 2-year life cycle, pink salmon from con- 

 secutive years do not interbreed. This results 

 in two genetically distinct stocks. 



Royce (1962) reports the pink salmon pack 

 in Prince William Sound from 1910 to I960. 

 He demonstrates that several reversals in 

 odd- and even-year dominance have taken 

 place. After 1950, the even year has been the 

 strong cycle; however, the unexpected large 

 return of pink salmon in 1961 might be indi- 

 cative of the strengthening of the odd-year 

 cycle. 



Studies were begun at Olsen Bay, Alaska, 

 in 1960 to study life history, ecology, and 

 survival of pink salmon in an intertidal spawn- 

 ing area. Olsen Bay is located in Prince 

 William Sound where intertidal spawning (more 

 than 50 percent) is of major importance. The 

 ultimate objective is to determine the con- 

 tribution of the intertidal spawners to the 

 total production of pink salmon. 



This paper covers the first 2 years of in- 

 vestigations which were undertaken as an in- 

 ventory to describe the environment, assess 

 the characteristics and magnitude of the fish 

 populations, and measure rates of survival of 

 eggs and larvae. 



OLSEN BAY DRAINAGE 



General Area 



Location .- -Olsen Bay is located on the east 

 shore of Prince William Sound in the northern 

 part of Port Gravina at lat. 60° 45' N. and 

 long. 146°12' W. A research field station was 

 constructed at the head of the bay where two 



forks of Olsen Creek join to become the nnain 

 intertidal streann (fig. 1). 



The surrounding terrain is steep timbered 

 mountains, the tops of which are snow covered 

 most of the year. Streamflows are maintained 

 entirely by runoff and ground-water depletion. 



Climate .- -Olsen Bay is close enough to the 

 open sea for the climate to be tempered by 

 oceanic influence, Cordova, 30 miles south- 

 west, is the nearest place where daily weather 

 records are kept. These records show pre- 

 cipitation to be high (annual average, 98.64 

 inches), with the greatest amounts occurring 

 in the fall months (U.S. Weather Bureau, 

 1959). 



Records of precipitation and air tempera- 

 ture were kept during the summer months 

 the station was in operation in 1960 and 1961; 

 and during those periods in both years, Olsen 

 Bay had less precipitation than Cordova (table 

 1). The total annual precipitation at Cordova 

 was 89 inches in 1960 and 97 inches in 1961. 

 Probably Olsen Bay has less annual precipi- 

 tation than Cordova. Daily maxinnum and mini- 

 mum air temperatures for Olsen Bay and 

 Cordova are quite sinnilar. 



Intertidal Study Area 



The Olsen Bay intertidal study area con- 

 tains three streams: Olsen Creek (the nnain 

 stream). Middle Slough, and Little Creek 

 (fig. 1). The main stream is formed by the 

 convergence at the 11 -foot tide level of its 

 two streams. East Fork and West Fork, which 

 make up the principal Olsen Creek drainage 

 system. The 12-foot tide level (approximately 

 mean high tide) on the main stream was 

 chosen as the separation point between the 

 intertidal study area and the fresh-water area. 

 Middle Slough is a small stream with low 

 velocity, and only the intertidal portion is 

 available to spawning salmon. Little Creek, 

 also a small stream with low velocity, drains 

 from the east side of the drainage and is 

 utilized by spawners only in its intertidal 

 area. The surface flow of both these streams 

 freezes in winter and stops for unknown 

 periods. One snnall tributary joins the West 

 Fork at the 11 -foot tide level, and another 

 joins Olsen Creek at the 5-foot tide level. 



Table 2 shows the average intertidal area 

 of each of the spawning streams and the total 

 for the combined areas. An area of 39,375 

 square feet bounded by the 9- and 10-foot tide 

 levels contains the only pool in the intertidal 

 portion of the main stream. The pool takes up 

 approximately 30 percent of the area and seems 

 to discourage spawning by pink salmon, al- 

 though chum salmon (O. keta) have been ob- 

 served spawning there. The width of each 

 stream and hence the area available for sal- 

 mon spawning varies independently with 

 fluctuations in flow. 



