Research Document - 2000/163

Quota options for the geoduck clam (Panopea abrupta) fishery in British Columbia for 2001 and 2002.

By C.M. Hand and D. Bureau

Abstract

Quota options for geoduck clams (Panopea abrupta, Conrad 1849) for the 2001 and 2002 fisheries were calculated using new parameter estimates, and presented by Geoduck Management Area for the North Coast Region, West Coast of Vancouver Island Region, and Inside Waters Region. The habitat-based approach was continued from previous assessments where, for each geoduck bed, virgin biomass is estimated as the product of the spatial area of geoduck beds, estimated virgin densities and mean geoduck weights. Error ranges in each parameter estimate were combined to provide a range of biomass estimates, and a harvest rate of 1% was applied to derive quota options. Past harvest levels were incorporated into the process of applying a B_50% limit reference point. The resulting reduction in quota was 23% and 14% of the total potential quota in 2001 and 2002 and the closing of 57 and 24 geoduck beds, respectively.

Biomass estimates and quota options are higher in each Region in 2001 and in 2002. Increases are primarily a result of generally higher estimates of geoduck bed area and, to a lesser degree, to higher estimates for mean geoduck weight and density. For 2001 and 2002, 315 ha and 374 ha of new geoduck bed were discovered. Additional increases in bed area resulted from modified bed-area scaling factors, the inclusion of beds not fished in the last rotation for logistical reasons, or the conversion from imperial to metric charts. For the 2001 fishery, recommended low, medium and high quota options are 947 t (2.1 million lb), 2406 t (5.3 million lb) and 4020 t (8.9 million lb), an average increase of 56% over the previous 1998 quotas in the same rotational area. Quota options for the 2002 fishery are 1245 t (2.7 million lb), 2875 t (6.3 million lb) and 4480 t (9.9 million lb), an increase of 49% over 1999 quotas. Given the uncertainty in parameter estimates, these quotas should be regarded as upper reference points. It is recommended that a large-scale bed verification and mapping program be initiated, that more extensive analysis of survey and fishery data be undertaken with spatial software, and that a rigorous assessment of the resource and management system be conducted.

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