SURVIVAL, MATURITY, ABUNDANCE, AND 

 MARINE DISTRIBUTION OF 1965-66 BROOD COHO SALMON, 

 ONCORHYNCHUS KISUTCH, FROM COLUMBIA RIVER HATCHERIES 



Robert H. Lander and Kenneth A. Henry* 



ABSTRACT 



Data are presented estimating the survival, maturity, and abundance of marked coho salmon, 

 Oncorhynchiis kisutch, of the 1965-66 broods from 18 to 20 Columbia River hatcheries. Also 

 presented are data depicting the distribution of these fish as caught in the northeastern 

 Pacific Ocean. Compared to fish from hatcheries on the upper reaches of the river, coho salm- 

 on from hatcheries near the estuary had a better survival until recruitment to the ocean 

 fishery, a greater proportion maturing as jacks (2-yr olds), and an apparent differential 

 migration pattern in the ocean. For hatcheries from all river sections combined, the param- 

 eter estimates differed little between broods. Estimates for both broods are as follows: 

 9-10% surviving during the 6.0 mo between release of smolts and the return of young males or 

 jacks to the Columbia River; 3-4% of survivors maturing as jacks; 10-12% surviving during the 

 last 12.0 mo of ocean life; 5-6% of the original number of smolts surviving until the time of 

 recruitment to ocean fishing 13.5 mo after release; and exploitation rates of 68-70% in the 

 ocean fishery during the last 4.5 mo of life at sea. 



A cooperative program was undertaken among 

 the various Pacific coast fishery agencies in the 

 United States and Canada to estimate the con- 

 tribution to various fisheries of coho salmon, 

 Oiicorhynchus kisutch, produced by 20 Colum- 

 bia River hatcheries. The hatcheries were placed 

 into four groups according to their locations on 

 the river (Figure 1). About 10% of the fish 

 released from each of the hatcheries on each of 

 the four river sections were identified with 

 section-specific marks (certain fins or bones 

 excised) for the 1965-66 brood years: 



Group 



Location boundaries Fins or bones excised 



' Northwest Fisheries Center, National Marine Fisheries 

 Service, NOAA, Seattle, WA 98 1 12. 



Manuscript accepted January 1973. 



FISHERY BULLETIN: VOL. 71, NO. 3. 19/j. 



I Kloskonine 5 Toulle 14 Coscod* 20 Leovcnworth 



2GraysRiver 6 LowerKolomo 15 Oxbow * 



3 Big Creek 7 KolomoFoMs 16 Corson* 



4 Erokomin 6 Lewis River 17 Liltle White Solmon 



9 Speel>oc |8 Willord 



10 EogleCreek 19 Klickilol 

 I I Sondy 

 )2 Woshougol 

 13 Bonneville 



* Did not porlicipole m 1966 brood study 



Figure 1. — Grouping of Columbia River hatcheries by 

 release area and marks applied to evaluate the contribu- 

 tion of 1965-66 brood coho salmon. 



Such studies are needed to determine the 

 economic justification for the large scale hatch- 

 ery program that has been developed for the 



679 



