HABITAT THRESHOLDS AND BOTTLENECKS IN PRODUCTION OF THE SPINY LOBSTER(PANULIRUS-MARGINATUS) IN THE NORTHWESTERN HAWAIIAN-ISLANDS

Variations in landings from the lobster fishery among banks of the nor thwestern Hawaiian Archipelago were compared with bank topography and benthic habitat characteristics. Summit depth, harvest area, amount of shallow habitat, and latitude were considered in relation to pre-expl oitation research catch rates and 6 years of commercial fishery landin gs. A threshold between lobster production and the depth of bank summi t was observed; banks with summits deeper than 30 m yielded few lobste rs. The effect of benthic habitat relief was then examined for three s elected, bathymetrically similar banks, two commercially productive an d one unproductive. Percent cover of habitat variables with characteri stic relief such as sand, algae, and coral outcrops were measured on e ach of the banks during 70 scuba dives. Juvenile lobster stages were f ound significantly associated with habitat scale. The nonlinear relati onship indicated both high and low extremes in relief yield poor catch per unit of effort (CPUE). Only the variable intermediate relief (5-3 0 cm) was associated with high sublegal lobster CPUE. The two producti ve banks had much more benthic relief at this scale than did the unpro ductive, suggesting that the abundance of intermediate relief habitat represents a bottleneck to adult lobster production.