K. Reid et As. Brierley, The use of predator-derived krill length-frequency distributions to calculate krill target strength, CCAMLR SCI, 8, 2001, pp. 155-163
The relationship between krill abundance and predator performance is fundam
ental to an ecosystem-based approach to resource management. We propose a m
ethod using krill sampled from the diet of predators to provide a length-fr
equency distribution of krill at times when it is possible to run automated
shipboard acoustic systems but not to conduct scientific netting, i.e duri
ng logistic/resupply operations, This will allow a robust estimate of krill
abundance to be calculated from acoustic data. Changes in the length-frequ
ency distribution of krill over a period of a few weeks produced a 10% diff
erence in TS, whereas simultaneous samples from predators and nets produced
only a 1% difference, illustrating the need for simultaneous length-freque
ncy data. By integrating data from land-based predators directly with autom
ated on-board data collection systems it will be possible to gain important
estimates of krill biomass at times of the season hitherto unavailable fro
m shipboard scientific surveys.