Sydney, September 23
Rescuers are attempting to free a pod of long-finned pilot whales stranded off the Australian island of Tasmania. Around 470 whales are within the pod, greater than half of which have already died, in one of many world’s largest beachings.
WHY DO WHALES BEACH THEMSELVES?
It’s the query that has puzzled marine biologists for years, and continues to take action. Mass whale strandings have occurred all through recorded trendy historical past, and sure earlier.
“Strandings around the world are complete mysteries,” mentioned Vanessa Pirotta, a Sydney-based wildlife scientist.
While scientists do not know the precise cause, they do know that whales – and dolphins, that are additionally susceptible to mass beaching – are very sociable animals. They journey collectively in pods, typically following a pacesetter, and are recognized to collect round injured or distressed whales.
“There are many different factors that can cause a stranding,” mentioned Australian authorities marine scientist Kris Carlyon mentioned. “Often it’s simple misadventure – one or two or a few animals get themselves into trouble and the rest of the group might follow them in.”
Many of the recorded mass strandings embrace long-finned or short-finned pilot whales – a species of oceanic dolphin that grows 7 metres (23 ft) lengthy and may weigh as much as three tonnes.
Olaf Meynecke, a whale researcher at Australia’s Griffith University, mentioned pilot whales use refined sonar to search out prey and for orientation, so some theories hyperlink strandings to modifications in electromagnetic fields.
“These changes can be caused by solar storms or earthquakes (seismic activities) but there is also a strong connection between active sonar, e.g. naval sonar, and dolphin strandings including pilot whales,” Meynecke mentioned.
HOW ARE THEY RESCUED?
Refloating stranded whales from seashores and sandbanks is a labour-intensive, tough and infrequently harmful job.
Several individuals are wanted per whale to attempt push them again into deeper water at excessive tide. Harnesses and stretchers are sometimes used, generally to connect a whale to a ship to be dragged out to sea.
Rescuers attempt to hold the whales upright to keep away from disorientation.
“It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help,” mentioned Meynecke.
The carcasses of people who do not survive are disposed of by being dragged into open sea or buried onshore, each additionally arduous duties.
BEACHING EVENTS AROUND THE WORLD
New Zealand and neighbouring Australia are hotspots for mass whale strandings, due to massive colonies of pilot whales dwelling within the deep oceans surrounding each island nations.
“They are feeding on squid in the offshore waters in these areas and it is where some of their main food sources occur supporting many thousand pilot whales,” Meynecke mentioned.
The largest mass stranding in trendy recorded historical past was 1,000 whales on the shores of the Chatham Islands, a New Zealand territory within the Pacific Ocean in 1918.
Pilot whales are repeatedly trapped in Farewell Spit, a slim sand bar that stretches out from probably the most northern level of New Zealand’s South Island into the Tasman Sea for about 26 kilometres (16 miles). About 600 pilot whales beached there in February 2017.
In Australia, the latest mass stranding concerned round 150 short-finned pilot whales off the nation’s western coast in 2018. Australia’s largest ever beaching was 320 long-finned pilot whales, additionally off its western shoreline, in 1996.
Cape Cod in Massachusetts, a hook-shaped peninsula extending into the Atlantic Ocean, is one other international hotspot, with a median of greater than 200 stranded whales or dolphins annually.
More than 300 sei whales died in distant waters off Patagonia, Chile, in 2015.-Reuters