Assessment of escape mortality of Antarctic krill (Euphausia superba) in trawls

The overall purpose of this study was to estimate the mortality rate of Antarctic krill (Euphausia superba) that escape from the most common mesh size used in the current commercial fishery. The experiment was carried out on the krill fishing grounds off South Orkney Islands (60°35’S, 45°30’W), during January-February 2014. The method applied consisted of a covered trawl codend system for retaining escapees, thereafter kept on the surface in tanks to monitor rates of mortality. Hauling depth and duration as well as handling effects on land including exposure to temperature differences likely influenced on the mortality rates found. A decrease in body length was also found significantly correlated with increased mortality rate. The escape mortality rate from experiment parallels and considered to be closest to a realistic catching process in a 16 mm mesh size, was found to be 1-6%. Krill may be more tolerant to mechanical damage than other taxon due to their durable exoskeletons.