Stock assessments for British Columbia herring in 1983 and forecasts of the potential catch in 1984 / by V. Haist and M. Stocker.: Fs97-4/1751E-PDF

"Herring stock abundance in British Columbia waters was assessed for 1983, and forecasts were made for 1984 using three methods: (1) Hourston's method, (2) age-structured model analysis, and (3) surplus production model analysis. The abundance of the 1983 adult herring run in British Columbia waters assessed by Hourston's method was 344,000 tonnes. This is a decrease of 46,000 t (12%) from 1982. The 1984 run is forecast at 266,000 t with average recruitment. The 1984 forecasts for poor and good recruitment are 203,000 t and 375,000 t respectively. Average recruitment would provide a potential catch of 91,000 t. The potential catch predictions from age-structured model analysis, for 1984, do not vary greatly between the "constant" and "variable" assumptions. For the B.C. coast the catch estimates are 49,700 t and 47,900 t for the "constant" and "variable" assumptions respectively. Assuming average production the surplus production model analysis predicts a potential catch for 1984 of 162,000 t and 175,000 t for the "constant" and "variable" assumptions respectively. These unusually high catch levels result from poor model fits obtained for most of the separate stock data sets. The recommended target quota (20% of the weighted 1984 herring run size) is 61,000 t. Under conservative management and other constraints encountered administering fisheries, the catch levels recommended herein may be substantially reduced"--Abstract, page iv.

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