C-27 



MANAGEMENT AND CONSERVATION CONCERNS 



Management concerns from an Antarctic ecosystem per- 

 spective in the area of environmental sensitivity to a 

 krill harvest are: 



(1) recovery rates of baleen whale populations. 

 Baleen whales are not a significant predator on krill at 

 present. Even when whale populations were greatest, baleen 

 whales probably consumed only about half of the krill avail- 

 able to predators (Green, 1975). Recovery rates of baleen 

 whale populations depend on the age ^t which whales reach 

 sexual maturity as well as on total population numbers. 

 Whales now become sexually mature sooner than they did at 

 the turn of the century (Gambell, 1976). This promotes a 

 rapid recovery of the population and may be due to good 

 physiological condition from abundant food supply. A reduc- 

 tion in krill might cause a rise in the age of first repro- 

 duction and, consequently, slower recovery of the baleen 

 whale populations. In addition, a harvest will be competi- 

 tion for food, limiting the potential sustainable baleen 

 whale population size. 



(2) abundance of potentially harvestable fish and 

 squid. Fish and squid are potentially harvestable resources. 

 They are probably easier to market than are krill even though 

 they may be more difficult to catch. Some commercial fish- 

 ing is already occurring in Antarctic waters. A substantial 

 krill harvest could interfere with existing and potential 

 fisheries by reducing prey availability and consequently 

 overall population size, 



(3) populations of penguins and seals. A large krill 

 harvest acting as a competitor for penguins and seals could 

 easily result in a reduction in penguin and seal populations. 

 The most affected would be crabeater seals, a potentially 

 harvestable resource. 



(4) trophic structure of the Antarctic marine ecosys- 

 tem. The harvest of krill is not analogous to the harvest 

 of whales. A whale is a top carnivore or an end of a food 

 chain. Some baleen whale populations were reduced to less 

 than a fifth of their highest levels. While there have 

 been adjustments within the Antarctic ecosystem to changes 

 in whale populations, the basic structure of the system 

 remains the same. If krill populations were reduced com- 

 parably, the entire character of the Antarctic ecosystem 

 would be changed. 



Some additional information is necessary for the 

 conservation and manapeTnp>nt n-F krill stocks. Breedinor 



