Bioacoustic study of krill (Euphausia superba) in the Bransfield Strait, Antartica

Abstract

Hydroacoustic evaluation of the distribution and biomass of krill (E. superba) was held on board the BIC Humboldt, in February 2013. The area evaluated between the Bransfield Strait and near the Gibbs Island totaling 11,712 nm2. During the day, krill swarms were record at high densities between 20 and 50 m deep, during the night dispersed and scattered swarms were detect from the surface to 20 m deep. The highest densities were observe at the eastern end of Bransfield Strait, followed by a regular distribution between the islands King George and Gibbs with average densities (500-1,000 m/mn²) and high (> 1000 m/mn²). A low density core was observed between Deception and Torre islands. The temperature range of the swarms of krill was between -1.0 and 1.5 °C. Aggregations of krill were observe between 33.96 and 34.35 ups salinity. A hydroacoustic biomass of krill 876.368 t was estimated by Stochastic Distorted Wave Approximation (SDWBA) method.