c-v 



tons estimated consumption, not from some hypothetical 

 unused portion of the population. Potential harvest esti- 

 mates range from 70 to 150 x 10" tons annually. A harvest 

 at the higher end of that range would displace half of the 

 predators, causing large changes In the Antarctic ecosystem. 

 From an ecosystem perspective, a smaller sustainable yield, 

 say 30 - 60 X 10° tons, seems more reasonable. 



It Is difficult to calculate potential krlll harvest 

 from productivity of the stock Itself because of uncertain- 

 ties In the life span and development rates of krlll. 

 Whether the clrcumpolar krlll population consists of one or 

 several distinct breeding stocks is also unknown. 



Management and conservation concerns on a krlll harvest 

 from an ecosystem standpoint are a possible reduction in the 

 rate of recovery of baleen whale stocks and limitation of 

 eventual population totals, reduction in abundance of other 

 potentially harvestable populations such as fish, squid and 

 seals, and alteration of the trophic structure of the 

 Antarctic marine ecosystem in the event of overexploitation 

 because of the central position of krlll in the food web. 



A controlled harvest of krlll can provide some 

 essential data on krlll population parameters and the 

 response of the rest of the ecosystem to changing krlll 

 abundance. In addition to usual catch and effort fishery 

 data, nutrients, plant productivity, and populations of 

 krlll predators should be monitored. 



