A proposal to subdivide CCAMLR Statistical Division 58.4.1 using environmental data

A precautionary catch limit for krill was established for CCAMLR Division 58.4.1 in 1996 based on the results of an acoustic survey (BROKE) of the southernmost 873,000 km2 of this area (CCAMLR 1996). Detailed subsequent analysis of the results of this survey have indicated that Division 58.4.1 is not meridionally homogeneous in its oceanographic or biological characteristics. Division 58.4.1 can be divided into two approximately equal sized subdivisions: 80-115?E and 115-150?E on the basis of environmental data. Krill is more abundant in the western subdivision and its biomass is more latitudinally extensive in this area. This observed pattern appears to be historically stable. Because of the unequal distribution of krill in this Division, and because of its extremely large size (4.68 million km2) we propose the formal subdivision of Division 58.4.1 into two based on the analysis of the scientific data collected on BROKE. The revised krill biomasss estimates for these areas are: 3.04 million tonnes for the western portion and 1.79 for the eastern one. We suggest the calculation of new precautionary catch limits for the two subdivisions of Division 58.4.1 based on the revised krill biomass estimates.