Estimating the density of Antarctic krill (Euphausia superba) from multi-beam echo-sounder observations using distance sampling methods


Martin J. Cox, Pelagic Ecology Research Group, Gatty Marine Laboratory, University of St Andrews, St Andrews, KY16 8LB, UK.


Summary.  Antarctic krill is a key species in the Antarctic food web, an important prey item for marine predators and a commercial fishery resource. Although single-beam echo-sounders are commonly used to survey the species, multi-beam echo-sounders may be more efficient because they sample a larger volume of water. However, multi-beam echo-sounders may miss animals because they involve lower energy densities. We adapt distance sampling theory to deal with this and to estimate krill density and biomass from a multi-beam echo-sounder survey. The method provides a general means for estimating density and biomass from multi-beam echo-sounder data.