Antarctic krill and ecosystem monitoring survey off the South Orkney Islands in 2024

Abstract

Environmental monitoring along 5 set transects off South Orkney Islands in the Southern Ocean have been carried out annually (since 2011) by the Institute of Marine Research, Norway. Hydro-acoustic as well as net derived data are used to calculate biomass of Antarctic krill (Euphausia superba) but also to assess spatial distribution and demographic composition of krill and other macrozooplankton and fish taxa. Systematic sighting data of cetaceans, penguins and pinnipeds are registered along the transects during daylight hours. Acquisition of data from the deployment of sensors that have been anchored to the seabed since previos year is also part of the procedyre. During this survey, trials were made to develop a method for extracting krill total body length frequency data by processing images from a custom build stereo camera that was attached inside the trawl. Using a custom-trained machine learning model, detection of krill segments shall be used to construct three-dimensional images that form the basis for the automated length measurements, and this will be validated against manually measured sub-samples of krill taken from each haul. The standard procedure for calculating biomass from acoustic data depends on input of representative length measurement variables from the same area and time period. This is part of a development process of automating krill biomass monitoring, which will form an important element of a data feedback management system regulating commercial fisheries. During this survey we also tested possibilities for satellite tagging whales in order to be able to study migration patterns and foraging behavior. Herein we report on the survey activities from 2024 and present preliminary results.

Antarctic krill and ecosystem monitoring survey off the South Orkney Islands in 2024