



Figure 1. -Mature pink salmon-male (upper), female (lower). 



in southern British Columbia and Puget Sound, runs large 

 enough for profitable commercial fishing occur only in 

 odd years. Conversely, in western Alaska since 1954, the 

 even-year runs have been the larger. Fortunately the 

 major pink salmon-producing areas of Alaska do not suf- 

 fer from this type of off-year scarcity. 



Spawning 



Pink salmon usually ascend streams only short dis- 

 tances to spawn, although in British Columbia and Cali- 

 fornia some migrate more than 200 miles from the sea to 

 the spawning grounds, and in Asia they migrate up to 

 400 miles from the sea. In Alaska, pink salmon typically 

 spawn in the lower reaches of short coastal streams, 

 although many use the intertidal areas of these streams, 

 where the eggs are alternately bathed by fresh and brack- 

 ish water as the tides ebb and tlow (fig. 4). In Prince Wil- 

 liam Sound, for instance, between 50 and 75 percent 



of the pink salmon fry are produced in intertidal zones. 



Spawning usually begins in August or September when 

 stream temperatures are about 50 F. Water tempera- 

 tures near freezing are common in winter. The spawning 

 season and the time of fry emergence are related to the 

 temperature regimes of the streams. Pink salmon tend to 

 spawn earlier in colder streams and later in warmer ones. 

 The eggs hatch from 3 to 5 months after they are spawned, 

 but the try remain in the gravel until .April or May. 



To prepare the spawning nests, the females dig pock- 

 ets, called redds, in riflles with gravel bottoms. The redds 

 are from 4 to 10 inches deep, depending on the size of 

 the female and the velocity of the water current. After 

 she has dug her redd, the female releases her eggs a few 

 at a time and the male releases a cloud of milt containing 

 sperm which fertilize the eggs as they fall to the bottom 

 of the redd. Egg laying is alternated witli more digging 

 at the upstream face of the redd so that each release or 

 cluster of eggs is quickly covered with sand and gravel, 



