Intertidal Ecology and Life History of Pink Salmon a\ 

 Olsen Creek, Prince William Sound, Alaska 



by 



John H. Helle, Richard S. Williamson, and Jack E. Bailey- 

 Fishery Biologists Research 

 Bureau of Commercial Fisheries Biological Laboratory 

 U.S. Fish and Wildlife Service 

 Auke Bay, Alaska 



ABSTRACT 



Intertidal spawning of pink salmon is of major importance in Prince William 

 Sound. Studies were initiated at Olsen Bay in 1960 to ascertain how much these 

 intertidal spawners contributed to the total production of pink salmon. 



Olsen Creek is inundated with tidewater about 80 percent of the time at the 

 3-foot tide level and about 7 percent of the time at the 11-foot level. Saline water 

 was shown to penetrate the gravel at redd depth during high tides. The highest con- 

 centration at the 11 -foot tide level was 9. 3°/oo during a 14.5-foot tide. Temperature 

 changes of up to 10 F. would occur within 1 hour at elevations up to the 8-foot level 

 on floodtide. 



The occurrence of spawners in 1960 and 1961 was bimodal; however, in 1960 

 the late run utilized only the intertidal spawning area, while in 1961 the late run 

 utilized both the intertidal and fresh-water areas. During the 2 years the early run 

 spawned in both environnnents. In 1960, 98,574 pink salmon spawned in Olsen Creek 

 and in 1961, 135,905 spawned. During both years 74 percent of the total run spawned 

 in the intertidal portion of the stream. 



Temporal and spatial distribution of spawners, size differences, and seasonal 

 changes in sex ratios provide evidence for the existence of discrete spawning groups 

 or races. 



Live egg densities and survival over winter to the preemergent fry stage were 

 progressively greater from the lower to the higher levels in the intertidal area. 

 Overwinter survival between egg and fry stages below the 4-foot level was 0, Sur- 

 vival at the 7- to 9-foot level and the 10- to 11-foot level was 20 and 54 percent re- 

 spectively. 



INTRODUCTION 



Pink salmon ( Oncorhynchus gorbuscha ) re- 

 produce in intertidal (defined here as the 

 portion of stream inundated by periodic tidal 

 flow) as well as strictly fresh-water portions 

 of many streams along the southern and 

 southeastern coast of Alaska. Hunter (1959) 

 reports the occurrence of intertidal spawning 

 in British Columbia, Canada. In many streams, 

 steep gradients or waterfalls occur at the 

 high tide level and only the intertidal zones are 

 available to spawners; but even when both 

 types of environment are present and up- 

 stream areas are uncrowded or barren of 



spawners, pink salmon will reproduce in the 

 intertidal zone (Conkle).' 



Hanavan and Skud (1954) in their study of 

 intertidal spawning of pink salmon at Lover's 

 Cove stream in Southeastern Alaska found that 

 survival of spawn in the area between the 4- 

 and 11.5-foot tide levels was as high as or 



' Temporal and spatial relationships of spawning pink 

 salmon in a Prince William Sound stream. A paper read 

 at the Twelfth Alaskan Science Conference, College, 

 Alaska, 1961. On file Bureau of Commercial Fisheries 

 Biological Laboratory, Auke Bay, Alaska. 



