Trends in abundance and pre-season 2000 stock size forecasts for major sockeye, pink, and chum salmon stocks in the central coast and selected salmon stocks in northern British Columbia / D. Rutherford...: Fs70-1/2000-114E-PDF

This working paper includes pre-season 2000 stock size forecasts for nine sockeye, five pink and five chum salmon stocks or stock groupings in central and northern British Columbia, statistical areas 1-10. The forecasts are based on simple methods assessed and recommended in previous working papers. Salmon fry recruitment and smolt production at Babine Lake (Skeena River) was dramatically reduced by parasitic infections at the Babine Lake Development Project sites in 1994 and 1995. To be precautionary, and to include biological information relevant to these abnormal conditions, forecasts for Skeena River sockeye in 1998 and 1999 were based on the smolt and sibling age-class models rather than the 5-yr average model. These biological forecasting models are used again to forecast Skeena river sockeye recruitment from brood years returning in 2000. Sockeye returns to Rivers and Smith Inlet in 1999 were well below forecast and reached record lows of 4,257 and 5,900 respectively. These low returns reflect exceptionally poor marine survival of smolts entering the ocean in 1996 and probably 1997 too. If these conditions continue, the 5-yr mean model will overestimate returns for these stocks again in 2000. Accordingly, forecasts were also computed under the pessimistic scenario that conditions for marine survival have not improved, and under the optimistic scenario that marine survival has returned to the long term average.

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