Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p35
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 35/48)
Character Range: 157449–160426

with contraction to their southern limits and resulting in possible declines in abundance and/or biomass (Murphy et al. 2017, Atkinson et al. 2019, Veytia et al. 2021). Climate change alters the extent and structure of sea-ice environments, and krill are highly dependent upon sea-ice habitats for survival in their early life stages (Murphy et al. 2007). Climate change is predicted to negatively impact krill and whale population dynamics, with predicted declines in southern right whale abundance resulting from krill biomass (particularly in latitudes 50 - 60°S) and increased interspecific competition between whale species (Tulloch et al. 2019).

    3.8.2     Prey depletion from overfishing
Over-exploitation of prey stocks may impose a further major threat to southern right whales that are dependent upon them for food (section 2.9). Antarctic krill (Euphausia superba) are an ecologically and commercially important species in the Southern Ocean (McBride et al. 2021), with the Antarctic Krill Fishery being the largest fishery by tonnage in the Southern Ocean (Nicol et al. 2012). The krill fishery is managed through CCAMLR on an ecosystem basis that takes into account the needs of predators such as whales (McBride et al. 2021). Risk frameworks for vulnerable marine ecosystems, seabirds, and marine mammals have been developed.
Australia is a Member of CCAMLR, and krill fishery catch limits off the Australian Antarctic Territory are determined using a precautionary approach that aims to minimise the threat of overfishing by krill fisheries to species such as southern right whales. The CCAMLR Working Group on Fishery Stock Assessments undertake regular risk assessments of the fishery. Vulnerable marine ecosystems and impacts on the environment, including impacts to food chains, are considered in the management of CCAMLR fisheries.

    3.8.3     Prey depletion from seismic survey
Current understanding of the potential impacts of seismic survey airgun noise on zooplankton is limited, despite their importance in marine ecosystems, although high mortality can occur on small localised scales of < 10 m (Fields et al. 2019). Exposure of zooplankton to the intense, low-frequency, acoustic impulse signals in the first large experimental field setting found a decrease in zooplankton abundance with associated mortality within the area of seismic activity up to 1.2 km from the source (McCauley et al. 2017). A modelled simulation scenario based on these findings, utilising the same mortality rates and ocean circulation models, found the decline in zooplankton can be spatially dependent and affected by ocean circulation. Zooplankton biomass within 15 km recovered quickly (~ 3 days) based on fast growth rate parameters. Greater declines were estimated at closer distances (up to 15 km), with minimal impact at regional scales (≥ 15 km) (Richardson et al. 2017).
Any impacts of seismic activity on prey abundance or distribution are unlikely to have