JOINT COHO TECHNICAL COMMITTEE

Joint Coho Technical Committee. Interim Estimates of Coho Stock Composition for 1984-1991 Southern Area Fisheries and for 1987-1991 Northern Panel Area Fisheries. TCCOHO (94)-1. February 10, 1994.

In 1988, the Pacific Salmon Commission instructed the Coho Technical Committee (CoTC) to develop methodologies for estimation of stock compositions of coho harvested by Southern Panel area fisheries. Over the past year, the feasibility of applying these methodologies to estimate stock compositions for Northern Panel area stocks and fisheries has been explored. This report presents interim stock composition estimates based on the progress of research to date.

After investigating a number of approaches, including run reconstruction and production factor estimation, the CoTC determined that analysis of coded-wire-tag recovery data provided its first estimates of stock composition for Southern Panel area fisheries for 1984 through 1986 (CoTC, 1989) based on a Constrained Least Squares estimation model. Interception estimates associated with these stock compositions are summarized below.

Interim Estimates of Coho Salmon Interceptions By Southern Panel Area Fisheries, 1984-1991 and Northern Panel Area Fisheries, 1987-1991 (Thousands of Fish). Based on Constrained Least Squares Estimation and Recoveries of Coded-Wire-Tags.

 

Southern Panel Area Northern Panel Area
Year Canadian
Interceptions of
U.S Coho Stocks		 U.S Interceptions
of Canadian
Coho Stocks		 Canadian
Interceptions of
U.S Coho Stocks		 U.S Interceptions
of Canadian
Coho Stocks
1984 1,244.7 76.0    
1985 1,636.2 105.7    
1986 1,947.5 110.5    
1987 1,305.5 150.7 50.7 276.6
1988 1,087.7 155.8 29.0 127.7
1989 1,857.7 95.3 40.4 399.8
1990 1,079.3 160.2 122.3 559.8
1991 1,114.7 169.6 83.5 815.8

 

Further investigations into methodologies will be undertaken by the CoTC, including the refinement of estimation models and data. The estimates presented in this report are preliminary and, therefore, likely to be revised as work on development of joint methodologies progresses. Additional work is necessary to determine the sensitivity of the estimates to underlying assumptions. Furthermore, the statistical reliability of the estimates should be investigated and reported.