factors have been studied rather extensively 

 in the fresh-water environment but compara- 

 tively little in the intertidal zone. Kirkwood 

 (1962) and Tait and Kirkwood (1962) described 

 methods of assessing production of salmon 

 fry in the intertidal zones of streams in Prince 

 William Sound; Kirkwood (1962) showed that 

 survival of pink and chum salmon was higher 

 in the 8- to 12-foot (2.4- to 3.7-m.) tide levels 

 than in the 4- to 8-foot (1.2- to Z.4-m.) levels 

 and was negligible below the 4-foot (1.2-m.) 

 tide mark. Hanavan and Skud (1954) found that 

 the lower limit of survival was about 4 feet 

 (1.2 m.) above nnean low tide in Lovers Cove 

 Creek in southeastern Alaska. 



In 1960 the BCF (Bureau of Commercial 

 Fisheries) began studying the ecology of the 

 pink and chum salmon in the intertidal zones 

 of streams inOlsenBay, Prince William Sound, 

 to determine the factors that limit abundance 

 of pink and chum salmonin the intertidal zones. 

 Olsen Creek is one of the major spawning 

 streams for pink and chum salmon in Prince 

 William Soxind. Helle, Williamson, and Bailey 

 (1964) reported the results of the first 2 years 

 of investigations. 



The present paper describes the quality of 

 the intertidal streambed and the abundance, 

 timing, distribution, length, and fecundity of the 

 pink salmon spawning populations in the fresh- 

 water and intertidal areas of Olsen Creek in 

 1962 and 1963. These features are compared 

 between habitats and between years to deter- 

 mine possible causes of observed differences. 

 The quality of the streambed and the length of 

 adult pink salmon were determined also in 

 two small nearby intertidal streams. Middle 

 Slough and Little Creek, for comparison with 

 the data from Olsen Creek. 



Middle Slough and Little Creek are so small 

 that they were not divided into study sections. 



STREAMFLOW AND PRECIPITATION 



Because of the importance of streamflow in 

 the ecology of the spawning areas, we collected 

 data on flow and its related factor, precipita- 

 tion. The volume of streamflow is very closely 

 related to rainfall at Olsen Creek because the 

 watershed is steep and contains no lakes for 

 water storage. 



Beginning in 1961, BCF maintained gages 

 to record the level of the stream onboth forks 

 of Olsen Creek in the 3 summer months, and 

 used a Price* current meter to measure 

 stream discharge at various stream heights. 

 Because a long drought in 1962 resulted in 

 streamflows so low that the recorder on the 

 West Fork did not operate properly, only the 

 data for the East Fork for 1962-63 are con- 

 sidered here (fig. 2). Because concurrent 

 measurements in the two forks at all water 

 levels above the minimum flow for 1961-63 

 showed that the fluctuations were practically 

 identical in the forks, I believe the data for 

 the East Fork represent stream level fluctua- 

 tions adequately for all of Olsen Creek. The 

 concurrent data for the two forks of Olsen 

 Creek in 1961 were givenby Helle et al. (1964). 



Precipitation at Olsen Creek in 1960-63 was 

 measured only in July to Septennber, but the 

 daily observations for these 3 months (table 1) 

 were similar to those for Cordova (U.S. 

 Weather Bureau, 1961-64), which is about 48 

 km. from the bay. Therefore the figures for 

 the annual precipitation for Cordova are prob- 

 ably indicative of the annual precipitation at 

 Olsen Creek. 



DESCRIPTION OF STUDY AREA 



Olsen Creek is in Olsen Bay, which is in 

 Port Gravina on the eastern side of Prince 

 William Sound, Alaska. Olsen Creek is at the 

 head of the bay and has two branches, East 

 Fork and West Fork; the branches converge 

 at the 11-foot (3.4-m.) tide level to form the 

 main channel in the intertidal zone (fig. 1). 

 Middle Slough and Little Creek drain the east 

 side of the tideflat parallel to Olsen Creek. 

 Salmon can go up each fork of Olsen Creek 

 about 2.5 km., but this study mainly concerns 

 the area below the 12-foot (3.7-m.) tide level 

 (about mean high tide), which is considered to 

 be the boundary between the intertidal and the 

 fresh-water zones. The spawning grounds in 

 Middle Slough and Little Creek are entirely 

 intertidal. 



Olsen Creek was divided into five study 

 sections on the basis of ecological differences: 

 upper intertidal, holding pool, low gradient, 

 middle intertidal, and lower intertidal (fig. 1). 



QUALITY OF STREAMBED 



I based my evaluation of the quality of the 

 streambed in Olsen Creek on the sizes of 

 bottom materials in the spawning areas. An 

 analysis in 1961 had shown an increase inma- 

 terials less than 1 mm. in size from higher to 

 lower tide levels in the intertidal zone (Helle 

 et al., 1964). In 1962 this relation was investi- 

 gated in more detail. 



McNeil and Ahnell (1964) found an inverse 

 relation between streambed permeability and 

 the proportion of silt and fine sands in the 

 bottom materials. They also found that the 

 pink salmon spawning streams that contained 

 relatively low percentages of silt and fine 

 sand produced more salmon than streams 

 containing higher percentages of these mate- 

 rials. 



"^ Trade names referred to in this publication do not Imply 

 endorsement of commercial products by the Bureau of 

 Commercial Fisheries. 



