ALASKA'S FISHERY RESOURCES - THE PINK SALMON 



By 



JACK E. BAILEY, Fishery Biologist 



Bureau of Coinmercial Fisheries Biological Laboratory 



Auke Bay, Alaska 99821 



INTRODUCTION 



Pink salmon, Oncorhynchus gorbusclia, are called the 

 bread and butter fish of the Alaskan salmon industry 

 because they are the most consistently abundant of the 

 five Pacific salmons in Alaska-pink, sockeye, chinook, 

 coho, and chum. The name "pink" comes from the deli- 

 cate color of the tlesh of the pink salmon, which is also 

 known as "humpy" or "humpback" salmon because of 

 the hump that develops on the back of the spawning 

 male (fig. 1). 



DESCRIPTION 



As with all salmon, the pink salmon change their ex- 

 ternal color as they mature. In the late spring just after 

 the fry emerge from the streambed, they have a general 

 silvery appearance and their backs are often deep blue to 

 green. They are easy to distinguish from other salmon 

 fry because they do not have the dark bars or spots, 

 called parr marks, that are prominent on the sides of 

 other salmon fry, such as the chum salmon, which are 

 found most frequently with pink salmon fry (fig. 2). 

 During the first 3 months after they enter the ocean, all 

 young Pacific salmon are silvery and have a similar gen- 

 eral appearance, but experts can recognize pink salmon 

 by their small and numerous scales and by subtle differ- 

 ences in shape and color and in internal structures. In 

 about Augusi of their first year in the sea, juvenile pink 

 salmon develop on tiieir backs and tails the large dark 

 spots that are characteristic of the adults. 



At the end of their second summer in the ocean when 

 pink salmon begin their migration back to fresh water, 

 they have further changes in color and body shape. The 

 silvery sheen is replaced by dark sides and a white belly, 

 and the dark spots on the back and tail become more 

 prominent. At this time the males develop their pro- 

 nounced hump, as well as an elongated hooked jaw with 

 large sharp teeth. 



GEOGRAPHIC DISTRIBUTION AND 

 ABUNDANCE 



Pink salmon occur in streams from California to the 

 Arctic Ocean on the North American side of the Pacific 

 Ocean and from the Arctic Ocean south to Hokkaido 

 Island of northern Japan on the Asian side. Their oceanic 

 distribution extends from North America to Asia north 

 of the 40th parallel through the Bering Strait into the 

 Arctic Ocean. 



Although several attempts have been made to trans- 

 plant pink salmon to waters outside their natural range, 

 no new important fishery has been established. The 

 United States planted them in rivers in Maine, the Rus- 

 sians in tributaries of the Barents and White Seas of 

 northern Europe, and the Canadians in tributaries to 

 Hudson Bay and in rivers in the Maritime Provinces of 

 eastern Canada. None of these efforts resulted in runs 

 that survived more than a few cycles. 



Although pink salmon do not usually complete their 

 life cycle in fresh water, an accidental release of several 

 hundred fry resulted in a population that perpetuated 

 itself for a few cycles in Lake Superior. 



The geographic distribution tells us nothing of the 

 importance of a fish-it is the abundance that determines 

 its value to the fishermen, and the best available measure 

 of the abundance of pink salmon is the commercial catch. 

 The catch in Asia is about twice that in North America. 

 Puget Sound is the southern limit and Bristol Bay the 

 northern limit of commercially important runs in North 

 America. Alaska produces more than half of the North 

 American total, and southeastern Alaska produces about 

 half of Alaska's total catch. Other important pink salmon- 

 producing areas in Alaska are Prince William Sound, Cook 

 Inlet, Kodiak Island, and the south side of the Alaska 

 Peninsula. 



NATURAL HISTORY 



The life of the pink salmon begins in late summer or 

 early fall when the fertilized eggs are deposited in the 

 gravel and start to develop. These eggs hatch in mid- 

 winter; the fry emerge from the streambed in the spring 

 and migrate directly to sea. There they spend 14 or 15 

 months feeding and growing before they return to their 

 home stream to spawn and die. The life cycle of the pink 

 salmon is illustrated in figure 3, and some of the biologi- 

 cal characteristics of this species are compared with those 

 of the other Pacific salmon in table 1 . 



Pink salmon have the shortest and simplest life his- 

 tory of any Pacific salmon. Because they have a 2-year 

 life cycle and return to their native streams to spawn, 

 two genetically distinct lines occur in each stream. The 

 lines are called "even-" or "odd-year" on the basis of the 

 year in which the adults spawn. Differences in the num- 

 ber and in the size of the fish in the two lines have been 

 the subject of speculation for many years. In some areas, 

 only one line spawns in significant numbers, leaving fish- 

 erman with few or no fish in an "off year. For example, 



