Stock units and fisheries
The rock lobster fisheries extend from the Three Kings Islands in the north to the Snares Islands in the south, and to the Chatham Islands in the east.
J. edwardsii stocks
J. edwardsii (CRA) accounts for nearly all landings. There are currently ten quota management areas for CRA although one (CRA 10) is only an administrative designation and no fishing of any consequence is carried out there.
Preliminary morphometric studies have been conducted on run and resident J. edwardsii near Stewart Island. Study results show that the two groups can be distinguished on the basis of the telson length to carapace length ratio, but that such differences may be environmentally induced.
The lack of genetic differences between areas, the long larval phase and long-distance movements of adults in some areas all suggest a single J. edwardsii stock around the mainland.
Stock assessments have addressed individual CRA areas. For earlier assessments, the seven principal mainland areas were grouped on the basis of similarities in relation to:
- Size at maturity
- Timing of biological cycles
- Perceived interchange between areas.
As a result three sub-stocks were designated:
- Northern sub-stock (NSN): CRA 1 and CRA 2
- Central sub-stock (NSC): CRA 3, CRA 4, and CRA 5
- Southern sub-stock (NSS): CRA 7 and CRA 8.
Genetic and morphometric samples have not been collected at the Chatham Islands. In any case, because of their geographical isolation the rock lobsters from this area are treated as a separate stock for management purposes.
S. verreauxi stocks
S. verreauxi (PHC) is caught mainly in the north of the North Island and there is only one quota management area for all New Zealand waters.
Genetic and morphometric samples have not been taken for S. verreauxi. Because of the limited distribution of mature females near Cape Reinga, and the highly directional movements of tagged animals to this area, the species is considered a single stock.