Humpback Whale Recovery Plan 2005-2010
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Potential threats
- Climate and oceanographic change
Most of the world's leading scientists agree that global warming caused by human activity is occurring. The exact implications of these changes are unknown, but it is predicted that there will be reduced productivity of Southern Ocean ecosystems and unpredictable weather events caused by increasing ocean water temperatures, changing ocean currents, rising sea levels and reductions in sea ice.
The potential impacts of climate and oceanographic change on humpback whales are twofold:
- Habitat availability
Humpback whale migration, feeding, resting, and calving site selection may be influenced by factors such as ocean currents and water temperature. Any changes in these factors could affect humpback whale population recovery by rendering currently used habitat areas unsuitable.
- Food availability
Changes to climate and oceanographic processes may also lead to decreased productivity and different patterns of prey distribution and availability. Such changes would certainly effect dependant predators such as humpback whales.
- Prey depletion due to over harvesting
Humpback whales rely on krill as the main food source and require adequate supplies to accumulate energy reserves essential for migration and breeding. Depletion of krill through over harvesting may be a potential future threat for Australian populations of humpback whales. However, it should be noted that:
- the krill fishery is managed through the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) on an ecosystem basis which takes into account the needs of predators such as whales; and
- while the fishery is likely to grow, fishing currently occurs well within the current precautionary limits.