The Chatham Islands in New Zealand, which are surrounded by sharks, have seen 4,000 whales perish on their shores in the past 120 years.
Over the past week, two mass pilot whale strandings have occurred on two different areas in the Chatham Islands, an incredibly remote place off the eastern coast of New Zealand's South Island. According to marine mammal rescue organization Project Jonah, a total of 477 whales were stranded in just a few days.
Marine mammal strandings happen globally. They are a common occurrence, but the cause remains a mystery to scientists.
This area of New Zealand is not new to the phenomenon. The Chatham Islands is a whale stranding hotspot, and a deathtrap for whales. It is in the top three places for strandings to occur in New Zealand.
The remoteness of the area makes rescue efforts nearly impossible, especially when such large numbers of mammals wash up. The coastal areas are also populated by great white sharks, making it potentially dangerous for humans to attempt to refloat the stranded whales.
The largest stranding to occur in the Chatham Islands occurred in 1918, when 1,000 whales washed ashore at once. The New Zealand Department of Conservation estimates that over 4,000 pilot whales have stranded in the Chatham Islands since 1901.
Scientists have tried to make sense of what could be causing the strandings at these particular beaches, but so far, they can only guess.
Culum Brown, professor at the School of Natural Sciences at Macquarie University, told Newsweek that he thinks the pilot whales that strand in Chatham Islands are initially drawn to the area for food.
The area is home to an abundance of aquatic wildlife. Pilot whales feed mainly on squid, octopus and fish.
"I think they are initially drawn to the location for food but then the tides shift and perhaps a few get stranded but the others won't leave them so more get trapped," Brown said.
Pilot whales are socially complex creatures, with strong social bonds to each other. They travel in pods, meaning that if one becomes disorientated by the changing tides, then others follow.
Peter Evans, a professor at the School of Ocean Sciences at Bangor University, told Newsweek that it could be down to the shallow waters being adjacent to deep water areas.
"Particularly if the seabed is mud or sand, [it makes] it very difficult for whales to navigate using their sonar," Evans said.
He added that whales may enter this area for a wide variety of reasons.
"Simply accidentally, in pursuit of prey, or because one or more members of the group are sick (and the others follow). Occasionally, they can also be disoriented by sonar introduced into the environment by humans; this affects their dive cycle causing them to change behaviour such that they miss the important recovery dive that prevents nitrogen uptake after rising to the surface from great depths.
"The beaked whales are most affected by that, but this is less relevant to why certain sites get more mass strandings. Some researchers also believe that whales can strand in response to magnetic anomalies, but the extent to which whales may navigate by biomagnetism remains in doubt."
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October 14, 2022 at 08:01PM
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Island of Death Circled by Sharks Has Seen 4,000 Whales Perish in 120 Years - Newsweek
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