484 



Fishery Bulletin 90(3). 1992 



encing juvenile and adult stages may substantially 

 dampen this variation and produce fairly stable recruit- 

 ment to the fishery (Pollock 1986). 



In the Northwestern Hawaiian Islands (NWHI), a 

 substantial drop in catches and catch-per-unit-effort 

 (CPUE) of spiny lobster P. marginatus Quoy and 

 Gaimard 1825 was recently documented (Polovina 

 1991). This study examines whether these declines in 

 catches and CPUE are due to overfishing or to ocean- 

 ographic factors which impact spiny lobster population 

 dynamics. 



NWHI lobster fishery 



The NWHI region is an isolated range of islands, islets, 



banks, and reefs that extend 2775km northwest from 

 Nihoa Island to Kure Atoll (Fig. 1). In 1977 after re- 

 search cruises documented a substantial lobster pop- 

 ulation in the NWHI, a commercial trap fishery was 

 initiated. The fishery targeted two species: the endemic 

 spiny lobster P. marginatus and the slipper lobster 

 Scyllarides squammosus Mike-Edwards 1837. A fish- 

 ery management plan implemented in 1983 mandated 

 that vessels submit logbooks recording daily catch and 

 number of traps set (effort); the plan also established 

 a minimum harvest size for spiny lobster and prohibited 

 the harvest of egg-bearing females. Subsequent amend- 

 ments to this plan added a minimum legal size for slip- 

 per lobster and required that traps have escape vents. 

 In 1990, low catches and CPUE prompted a 6-month 

 closure of the fishery (May-November 1991). 



-« — N.|£quatorlol < ■ S i 

 Equatorial Counter » —n 



Kure I. 



^) , Mi<i»0, I. 



French Frigole 

 Shoals 



Figure 1 



Pacific Ocean and major cur- 

 rents with an inset of the 

 Hawaiian Archipelago, includ- 

 ing the Northwestern Hawai- 

 ian Is. 



