ESTIMATING THE VALUE OF IN-SEASON ESTIMATES OF ABUNDANCE OF SOCKEYE-SALMON (ONCORHYNCHUS-NERKA)

Fishwheels have recently replaced a gillnet test fishery for in-season estimation of escapement of sockeye salmon (Oncorhynchus nerka) to th e Nass River, British Columbia. We used an empirically based Monte Car lo simulation model to estimate the potential benefits (in terms of fu ture harvests) of using this new method. We found that using the infor mation from the fishwheels in place of the gillnet test fishery may in crease the average annual catch from current ocean fisheries by 2.7% ( $229 000) due to the greater accuracy of in-season estimates. When the additional costs of operating the fishwheels instead of the gillnet t est fishery were taken into account, the fishwheel program still resul ted in an annual net benefit of about $180 000. Eliminating the deviat ions from the target escapement for Nass River sockeye salmon by havin g perfect monitoring of escapement and perfect control over harvesting has a potential annual value of more than $1 million (CAN). However, much greater benefits from fishwheels are unlikely to be realized beca use of the highly variable response of the commercial fishing fleet to additional fishing opportunities and the 5-day lag of the escapement estimates provided by fishwheels.