CPUE was calculated as described for pink salmon using the 

 following efficiency factors: 



Puget Sound 



Gill net, set net, reef 







net, and drag seine 



1.00 





Indian trap 



7.36 





Purse seine 



1.98 



Area 20 



Canadian gill net 



0.63 





Canadian purse seine 



8.46 



Hatchery production. — Releases for upper Columbia River 

 hatcheries were adjusted as described for chinook salmon. Senn 

 (1970a, b) showed that the survival rate of coho salmon released 

 from hatcheries in northern Puget Sound is about 50% of that 

 for fish planted by other Puget Sound hatcheries. For Puget 

 Sound hatchery production, only one-half of the aggregate 

 weight of releases from northern hatcheries was included. 



Environmental conditions during preemergence. — We cal- 

 culated regressions of troll catch, troll CPUE, and sport catch in 

 areas north of Cape Elizabeth on rank indices (1 = lowest rate) 

 for pooled peak momentary discharge rates during October 

 (year i— 3) through February (year i— 2) in the North Fork of 

 the Stillaguamish, Skykomish, and Puyallup Rivers. Regres- 

 sions were also computed for the same dependent variables 

 against rank indices (1 = lowest temperature) of pooled air 

 temperatures at Sequim, Puyallup, Darrington, Concrete, 

 Newhalem, Quilcene, and Startup during the winter (October- 

 March) of preemergence. 



Summer streamflow during year i — 2. — Regressions of troll 

 catch and CPUE in areas north of Cape Elizabeth against ranks 

 of the average July-September flow rate in six Puget Sound 

 rearing streams (Newaukem Creek, Wallace River, Cascade 

 River, North Fork of the Stillaguamish River, Skykomish River, 

 and Puyallup River) were calculated. For each stream, average 

 flow rates were ranked from lowest (1) to highest. Then we 

 summed these ranks for each year and ranked the sums to ob- 

 tain the series of annual indices shown below. 



the Columbia River and Coastal Washington districts, 2) troll 

 CPUE in the same areas, and 3) combined annual sport catch 

 for Ilwaco and Westport on indices of Cascade Head upwelling 

 during April and April through June of the previous year. 

 Similarly, regressions were computed of 1) commercial ocean 

 troll catch in the Puget Sound and Vancouver Island districts, 2) 

 ocean troll CPUE in these areas, and 3) combined sport catch 

 for La Push and Neah Bay during June through October on in- 

 dices of Cape Flattery upwelling. 



Oceanographic conditions influencing catchability. — Regres- 

 sions of troll catch, CPUE, and sport catch on indices of upwell- 

 ing during April and April through June in year /' were 

 calculated. Also computed were the regressions of 1) monthly 

 troll CPUE in Canadian area 23 against mean surface sea 

 temperature and salinity for the same month at Amphitrite 

 Point and 2) monthly troll CPUE in Canadian area 27 against 

 the corresponding monthly means of surface sea temperature 

 and salinity at Kains Island. 



Jack returns.— We computed the regressions of 1) ocean troll 

 catch in the Columbia River and Coastal Washington districts, 

 2) troll CPUE in the same areas, and 3) combined Ilwaco- 

 Westport sport catch in year / on Columbia River jack counts in 

 year / - 1 . 



Average individual weight and monthly growth. — The 



average weight of troll-caught coho salmon was estimated as the 

 aggregate weight of the catch divided by the number of fish. The 

 average monthly weight increments were calculated as 



October average weight - July average weight . 



Then we compared annual troll catch, CPUE, and sport catch in 

 each area with 1) the average individual weight of coho salmon 

 caught there in August and 2) the average monthly weight incre- 

 ment. Also calculated were regressions of monthly troll CPUE 

 on monthly mean individual weight by area. 





Streamflow 





Streamflow 



Year 



index 



Year 



index 



1953 



14.0 



1964 



17.0 



1954 



20.0 



1965 



8.0 



1955 



18.0 



1966 



9.0 



1956 



13.0 



1967 



7.0 



1957 



2.0 



1968 



15.0 



1958 



1.0 



1969 



11.0 



1959 



19.0 



1970 



4.5 



1960 



10.0 



1971 



16.0 



1961 



4.5 



1972 



21.0 



1962 



12.0 



1973 



3.0 



1963 



6.0 







Oceanographic conditions affecting juvenile survival. — To 



estimate the influence of marine physical conditions upon sur- 

 vival during the first months of ocean residence, we calculated 

 regressions of troll catch and CPUE in areas north of Cape 

 Elizabeth on mean surface sea temperature and salinity at 

 Amphitrite Point during July through September of year /— 1. 

 Regressions were also calculated of 1) commercial troll catch in 



RESULTS 



Models discussed had the highest multiple correlation coeffi- 

 cients and smallest standard error of those developed. For each 

 species, the principal results are summarized, then details are 

 discussed in subsequent paragraphs. 



Pink Salmon 



1 . Troll catch south of Cape Flattery was highly correlated with 

 the level of nominal fishing effort. 



2. Troll catches in most areas were significantly correlated with 

 practically all indices of brood year abundance when com- 

 pared with Ricker curves. 



3 . Troll catches were highly associated with average individual 

 weight of pink salmon caught in terminal areas in the brood 

 year. 



We found no conclusive, consistently significant correlations 

 between indices of ocean fishing success and any environmental 

 factor. The following equation explained 80-85% of the varia- 

 tion in annual troll catch in most areas: 



