89 



Catch Tape recovered from catch Ratio 



year Origin of tag group Marine* Che. Basin* (Mar.+Che. ) /Che. 



1984 Chehalis system wild 949 

 Humptulips system wild 452 



1985 Simpson Hatchery 311 

 Chehalia system wild* 481 



1986 Chehalis system wild 1,083 

 Humptulips Hatchery 3,198 

 .Humptulips system wild 682 



1987 Chehalis system wild 329 



1988 Simpson Hatchery 366 

 Humptulips Hatchery 1,702 



Total Chehalis system 3,519 



Humptulips system 6,034 



289 

 63 



14J 

 «1 



540 



367 



56 



425 



S3 

 296 



1,S39 

 7B2 



3.29 

 8.72 



A. Sourcei: P»cificSui»t Mirjne Fuhery Coomiuioo ditto**, September 1991 1£ Wubiajton Department of Fuberiee uj 



recovery pubiicuiooe. 

 8. Source* Wufcingtoo Deptrunem of Fitberiee ttf recover}' publication tod daubue, September 1991. 



Table 9. Data used to calculate expansion factors for coho catch estimates. 

 Current Coho Run Sire and Historical Levels 



Table 9 indicates how the expansion factors for Chehalis Basin coho catches 

 were calculated. The current Chehalis Basin wild coho population is about 

 135,000 fish, clearly lees than the 229,000 reconstructed from historical 

 catch data (Table 10). The current hatchery run sire is about 131,000 (Table 

 11) so the combined wild and hatchery population of 266,000 appears to only 

 slightly exceed the historical level. This suggests that hatchery production 

 has replaced, not added to, natural production. 



The rapidly increasing hatchery influence since the late 1970 's, approaching 

 half the total escapement in 1990, raises concern regarding the long-term 

 adaptability of the total run to the Chehalis Basin. 



Terminal tag recoveries may or may not represent all estuarine and river sport 

 fisheries, depending on the year of recovery. The resulting tendency to 

 overestimate total catch may be more substantial than for chinook, since coho 

 sport catch averaged about 17.8 percent of the ■terminal area catch of Chehalis 

 Basin coho (NDF, unpublished data). 



32 



