Blue and sperm whales in the waters around New Zealand will migrate south to cooler waters as global warming continues. This reduces the habitat of the largest marine mammals.
the essentials in brief
- The study, conducted by the University of Zurich, the Universities of Massey and Canterbury in New Zealand, and Finders University in Australia, shows that the southerly shift of these whale populations increases as the oceans warm.
The habitat suitable for blue and sperm whales is likely to be reduced by 61 percent at worst and 42 percent at best. The northern waters of New Zealand would be mainly affected, as the University of Zurich announced on Monday.
Even in the best scenario, the habitat of the blue and sperm whales in New Zealand would change dramatically, says research leader Katharina Peters from the University of Zurich.
According to the study, island nations such as New Zealand are particularly vulnerable to climate change and the associated changes in the ocean. Sperm whales, for example, are tourist magnets in New Zealand and therefore an economic factor. Whale-watching tours in boats would plummet if fewer marine mammals were seen, wrote study co-author Karen Stockin of Massey University.
In addition to the economic impact, the ecological impact of the disappearance of large whales from a habitat is also costly, the study further points out.
Whales play an important role in the food chain. For example, they bring nutrients from deeper ocean layers to the surface. They also convey these substances on their migration between feeding and calving areas over several degrees of latitude.
The shift in habitat of the blue and sperm whales towards Antarctica will thus impair the functioning of the ecosystems around New Zealand and possibly destabilize ecological processes.
While the study highlights the negative impacts associated with ocean warming on populations of blue and sperm whales, it also points to the habitats both species find around the South Island and offshore islands of New Zealand. These sea areas could serve as climate refuges for them.
The previous knowledge of the areas in question represents a way to protect the sea giants. This applies in particular to the establishment of protected areas and legislation for the exploitation of oil and gas, it said.
The Sperm Whale (Physeter macrocephalus) is found in all oceans and is the only large whale among the toothed whales. The animal feeds mainly on squid from the deep sea. Large bulls can grow over 20 meters long and weigh over 50 tons. The females are significantly smaller.
The blue whale (Balaenoptera musculus) is one of the largest and heaviest animals on earth. Its length can be up to 33 meters and its weight 200 tons. On average, the animal grows to 26 meters in length, although its southern hemisphere counterparts are larger.
The blue whale can also be found in all oceans. The females are larger than the males. The blue whale is a member of the rorqual whale family. Like all baleen whales, it feeds on plankton.
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