Document ID: chunk:federal_register_of_legislation:F2013L00289:body:0:p31
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animals to reproduce in more marginal environments and by increasing their exposure to other risks such as entanglement, predation, vessel disturbance and pollution. Associated industrial activities in the coastal zone may also reduce habitat suitability.

Chronic chemical pollution and acute chemical discharge
Southern right whales may be exposed to pollution and high nutrient loads both during their time in Australian waters and on their feeding grounds, although the extent and implications of this exposure remain largely unknown. However, given that southern right whales feed primarily in the mid-high latitudes waters of the southern ocean, the impact of toxins from chemical discharge is likely to be low.

While in Australian waters they may encounter chemical pollution in the form of sewage and industrial discharges, and run off from onshore activities such as agriculture. This is most likely to create impacts in coastal aggregation areas. In their feeding grounds they are most at risk from bioaccumulation of human-made chemicals such as organochlorines most commonly from herbicides and pesticides and industries such as dry cleaning, tanneries and electrical equipment.

Southern right whales could also be exposed to acute chemical discharge, such as from accidental oil or condensate spills from oil rigs and other at sea operations.

G: Overharvesting of prey
Southern right whales rely on krill and copepods as a major food source and require adequate supplies of food to accumulate energy reserves for migration and breeding. Depletion of prey through over harvesting may be a potential future threat for the Australian population of southern right whales. Changes to climate and oceanographic processes may also lead to decreased productivity and different patterns of prey distribution and availability. Such changes would certainly affect dependant predators such as southern right whales. The extent to which dietary shifts could compensate for any reduction in krill availability is unknown. Currently, the krill fishery is managed through the CCAMLR on an ecosystem basis which takes into account the needs of predators such as whales, and fishing is believed to occur well within precautionary limits41,68,69,71.

5.2 Threat Prioritisation
Each of the threats outlined above has been assessed using a risk matrix in order to determine their impact on each of the south-west and south-east populations. This in turn determines the priority for action outlined in Section 6. The risk matrix considers the likelihood of occurrence of a threat relevant to southern right whales, and the consequences of that threat or impact considering existing mitigation measures. The precautionary principle dictates that the threat category is determined by the group at highest risk. Population-wide threats are generally considered to present a higher risk but the low numbers in the south-east population mean that threats acting at the individual level may also