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unregulated harvest to overexploit the krill population is 

 real . 



Commercial exploitation of krill may have direct im- 

 pacts on the stock other than a change in overall popula- 

 tion size. , Krill distribution patterns, productivity or 

 secondary production rates, or behavior such as swarming 

 patterns could also be affected. 



In evaluating the potential impacts of various har- 

 vesting levels on krill populations, the different time 

 scales of krill and predator populations must be taken 

 into account. The life span of krill may be 2 to 4 years. 

 The life span of krill predators such as a crabeater seal 

 may be as much as 30 years. Since adjustments of predator 

 populations to changes in krill abundance may take a long 

 time, consumption by a large predator population v/hich 

 has not yet adjusted to a decreasing krill population must 

 be taken into account in estimating impacts of harvesting 

 on the krill population as a whole. Time lags in response 

 vary for different predators, and are factors to be con- 

 sidered. 



The present level of krill harvesting in the explora- 

 tory phase is roughly 20,000 - 40,000 tons per year, 

 certainly too low for any direct impact on the krill stock. 

 Practical considerations limit the total krill harvest now. 

 Processing of krill must occur within a few hours of catch- 

 ing, and processing capacity is limited. Markets are not 

 yet extensive. However, with improving ability to locate 

 swarms, increasing vessel and processing capacities, and 

 rising demand for protein, krill harvesting operations may 

 soon be profitable. Considering the potential need to 

 redeploy long distance fishing fleets as a consequence of 

 extension of national fisheries limits (Eddie, 1977), the 

 potential capacity to overexploit krill probably exists 

 already. 



Several fish species are already harvested in the 

 Antarctic. Unregulated harvesting could lead rapidly to 

 local overexploitation. The fishery techniques for fish 

 harvesting are already well developed. 



The southern blue whiting, Micromesistius australis , 

 is a migratory fish. It is present in the Antarctic only 

 during the summer season while it is feeding there. The 

 rest of the year it is in the Magellanic and New Zealand 

 regions. Harvesting of this species would not be regula- 

 ted while it is outside the Antarctic ecosystem under the 



