CHARACTERISTICS OF THE BLOOD OF ADULT PINK 

 SALMON AT THREE STAGES OF MATURITY 



By Kenneth E. Hutton, Department of Biological Sciences 

 San Jose State College, San Jose, California 95114 



ABSTRACT 



Selected characteristics of the blood of adult pink salmon 

 (Oncorhynchus gorbuscha) were studied in fish at three 

 stages of maturity — migrating fish approaching the general 

 area of spawning streams but still in the open ocean, fish 

 in the immediate vicinity of the spawning stream but in the 



estuary, and fish in the spawning stream. Although some 

 hematological characteristics changed little, blood proteins, 

 glucose, and cholesterol decreased progressively, and lipid 

 phosphorus increased. 



The blood chemistry of salmon of the genus 

 Oncorhynchus is especially interesting because 

 of physiological changes that occur during the 

 spawning migration from sea water to estua- 

 rine waters of reduced salinity and then into 

 fresh water. This change in the environment 

 is concurrent with the final stages of matura- 

 tion. 



Some information is already available on 

 changes in blood characteristics at this time 

 of the life cycle. Lysaya (1951) found several 

 physiological changes in the blood with ad- 

 vancing sexual maturity in the Asiatic pink 

 salmon (0. gorbuscha) and chum salmon (0. 

 kefa). The erythrocyte count, the hemoglobin 

 concentration, and the blood glucose, chloride, 

 and calcium levels fell; and the erythrocyte 

 sedimentation rate and the blood urea and 

 nonprotein nitrogen concentrations increased. 

 Biologists of the Fisheries Research Board of 

 Canada found that adult sockeye salmon (0. 

 nerka) on their spawning migration up the 

 Eraser River lost 11 to 30 percent of their 

 body weight and had decreasing blood choles- 

 terol (Idler and Tsuyuki, 1958) ; liver gly- 

 cogen decreased, except for a terminal in- 

 crease (Chang and Idler, 1960) ; and concen- 

 trations of adrenal corticosteroid hormones 

 increased (Idler, Ronald, and Schmidt, 1959). 

 Chinook salmon (0. tshawytscka) during 

 their spawning migration up the Sacramento 

 River and its tributaries in California showed : 



FISHERY BULLETIN: VOLUME 66, NO. 2 



increased activity of the pituitary with term- 

 inal degeneration ; hypertrophy of the islets of 

 Langerhans; hyperplasia of the adrenal cor- 

 tices (a rise in concentration of 17-hydroxy- 

 corticosteroids ended with degeneration of the 

 adrenal glands) ; and the deterioration of the 

 stomach, liver, spleen, thymus, kidneys, thy- 

 roid, and cardiovascular system (Robertson 

 and Wexler, 1960, 1962; Robertson, Krupp, 

 Favour, Hane, and Thomas, 1961; Robertson, 

 Wexler, and Miller, 1961; and Robertson, 

 I^rupp, Thomas, Favour, Hane, and Wexler, 

 1961). 



In 1963, under the sponsorship of the Bu- 

 reau of Commercial Fisheries, I had the op- 

 portunity to study the hematology and blood 

 chemistry of adult pink salmon in three stages 

 of maturity in Alaska: (1) maturing fish in 

 salt water migrating toward the spawning 

 areas; (2) nearly mature fish milling in the 

 estuary of a small creek; and (3) mature fish 

 spawning in a fresh-water stream. This paper 

 reports the results of these studies. 



COLLECTION OF SAMPLES 



Pink salmon in the three stages of maturity 

 were taken from three stocks on different 

 dates. Those migrating toward the spawning 

 grounds (termed "migrating"), were taken 

 from the open ocean near the community of 

 Elfin Cove, southeastern Alaska. They were 

 captured on August 5, about a month before 



195 



Published April 1967 



