Alternative methods for determining subarea or local area catch limits for krill in Statistical Area 48

CCAMLR Conservation Measure 32/X sets a 1.5 million metric ton precautionary catch limit on krill (Euphausia superba) in Statistical Area 48. The measure also asks the Scientific Committee to provide the Commission with advice on how precautionary limits could be applied to subareas or local areas. Nine alternative methods of determining subarea or local area krill catch limits are evaluated relative to six criteria: 1) the degree to which information on biological relationships is considered, 2) the cost of data collection, 3) the reliability of required information, 4) the ease of enforcement, 5) the effects on current fishing patterns, and 6) the potential for delay in implementing the alternative. The probability of adverse impact on dependent species is minimized when a high amount of biological information is considered and the potential for delay is low. Therefore, we consider the following tradeoff to be important: choosing a biologically explicit alternative and delaying implementation, or choosing a biologically unrealistic alternative and implementing a management scheme immediately. We recognize that other tradeoffs may be equally important. Alternatives that allocate the 1.5 million ton limit by evenly dividing the catch among subareas or by using historical catches to set limits can be categorized as having a low potential for delaying implementation, but they ignore information on biological relationships. Alternatives based on protective zones, critical periods, predator censuses, and predator-prey models include large amounts of biological information, but may not be practical in the near future. Alternatives based on continental shelf area, simple pulse fishing, and krill surveys are not biologically explicit and result in delayed implementation. None of the alternatives are categorized as being both biologically explicit and immediately available for implementation. However, two of the alternatives (i.e. protective zones and critical periods) are unsatisfactory only because they would alter current fishing patterns. These two alternatives could be implemented immediately if the member nations are willing to tolerate changes in current fishing patterns.