C-28 



stocks must be identified. Data is needed on the abundance, 

 distribution, age structure, and reproductive physiology of 

 krill. 



Limited commercial harvesting can provide some of the 

 data necessary for calculating sustainable yields. In the 

 event of any krill harvest, data should be collected, 

 reported and analyzed: location, time, search time to 

 locate a swarm, gear used, swarm size, shape and depth, 

 size composition of the catch, and breeding condition. 



Monitoring the rest of the system for a response to 

 the krill harvest is also essential. Nutrient levels and 

 primary production rates in the vicinity of krill harvesting 

 should be measured. If possible, fish and cephalopod popu- 

 lations should be evaluated. Birds, particularly penguin 

 populations, should be monitored closely as potential 

 indicators of changes in krill abundance. Seal and whale 

 data are already being collected under existing conventions. 



A controlled krill harvest can be treated as an exper- 

 imental manipulation of the Antarctic marine ecosystem. With 

 careful observations, data pertinent to the ecology of the 

 system as well as to management of the fishery can be 

 obtained. 



