An overview of the ecosystem survey to quantify krill abundance for krill monitoring and management in Eastern Sector of CCAMLR Division 58.4.2: Trends in Euphausiids off Mawson, Predators, and Oceanography “TEMPO”

This report provides overview and early results of the multidisciplinary large-scale survey of the Eastern Sector of CCAMLR Division 58.4.2 conducted in February to March 2021. The survey consisted of six major acoustic line-transects to estimate krill biomass and to observe swarm behaviour across ecological and density gradients within the survey area south of 62°S between 55° and 80° E, with a single fine-scale krill box acoustic survey off the Mawson coast. The voyage successfully estimated mean areal biomass for the region. Along with acoustic survey we conducted net sampling, deployed swarm study system, deep-sea camera and light trap, deployed Krill Observational Moorings for Benthic Investigation (KOMBI)  on the seafloor that will record the behaviour of krill throughout a full year to understand the dynamics and use of habitat in the surface layer as well as at seafloor. Comprehensive oceanographic (CTDS, XBTs, ARGSO floats) and biological (plankton) sampling were also conducted to understand the habitat environment of krill and its predators. Predator observation was undertaken throughout the voyage to improve our understanding on predator abundance, distribution, and its relationship with krill distribution and their habitat environment. The information gathered contributes to the design of tractable and sustainable long-term monitoring plan and to evaluate spatial management of the krill fishery.