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- Sperm and bottlenose whales have been known to chase fishing boats to catch fish that escape the nets.
- Experts say it is an easy way to get food but it makes them more dependent on fishing boats.
- Whales are also at high risk of entanglement in fishing nets, which leads to thousands of deaths each year.
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Humans catch about 95 million metric tons of fish each year, contributing trillions of dollars to the global fishing industry.
Interestingly, some whale species have even found ways to profit from the fishing business.
They are not after the money – they are after the fish which outsmarts even the fishermen.
whales find a way to get a free lunch
Sperm whales and northern bottlenose whales have been repeatedly observed chasing fishing trawlers off the coast of Newfoundland to catch fish left over from fishermen’s nets.
But the whales didn’t catch any old fish. They were apparently finicky and only followed one ship when it was fishing for Greenland halibut.
None of the whales the scientists observed chased a trawler when it was catching fish other than redfish, spiny skate, or Greenland halibut. The scientists published their results in August in the journal PLOS ONE.
Fishermen’s nets are very large and whales can easily get entangled in the net by mistake if they get too close. usua oyarebide
“The whales have learned to identify fishing vessels as an easy source of prey, reducing the time it takes them to catch fish,” lead researcher Usua Oyarbide told Insider.
Oyarbide first observed this behavior in 2007 as part of his master’s thesis project. Then five to six years later, he said a fisherman sent him a video of one of the same whales still chasing fish.
This study is not the first to report whale and fishing boat encounters. Oyarbide said scientists have found similar behavior among at least 17 other whale species in different parts of the world since 1997.
“This is a behavior that has been reported more and more in many parts of the world over the past 20 years.” Hal Whitehead, a sperm whale expert and professor of biology at Dalhousie University, told Insider. He was not involved in Oyarbide’s study.
Even more interesting, whales are not the only ones that have learned to catch fish by avoiding fishermen’s nets.
The birds mingle with the whales in the hope of catching fish. usua oyarebide
“As time goes on we’re hearing more and more reports of everything from sperm whales to dolphins doing this. Presumably, nearly every species of marine mammal that eats fish takes advantage of a free meal from time to time.” picks up,” said director Andrew Triets. of the Institute for Marine Mammal Research at the University of British Columbia, who was not involved in the study.
Oyarbide further suggests that this behavior may become more common among whales in the future because whales learn from each other socially and, therefore, can pass on tips and tricks to the next generation, and so on.
Is it good to chase fishing boats for whales? No.
Oyarbide said this change in whale behavior may at first appear to be beneficial to them because it increases their access to prey and reduces the time it takes them to find food.
But it could make them more dependent on fish vessels for food, affecting their survival and reproduction. Oyarbide said the whales probably started chasing the trawlers because the boats were overlapping their feeding areas.
Overfishing in such areas threatens to indirectly reduce the availability of whales or change the size or diversity of their prey. “Understanding the impacts of fisheries on marine ecosystems is critical,” Oyarbide said.
Another issue is that “habitat degradation caused by bottom trawlers can have indirect, negative effects on marine mammals that depend on those habitats for food,” he said.
Fishing nets kill an estimated 300,000 marine mammals a year. Vince Strino / Getty Images
Rather than searching for food, some whales find it easier to catch prey by following trawlers. And that often leads to more risky contact with vessels or fishing gear, Oyarbide said.
“It’s probably bad for the whales in the long run,” Whitehead said. “They sometimes get hit, or shot by angry fishermen, and can get caught in nets. We saw a sperm whale killed by a trawler net close to the area mentioned in the study. Skills can also be lost.”
According to the International Whaling Commission, 300,000 whales, dolphins and other cetacean mammals die each year from entanglement in fishing gear alone. And a study published in January suggested that estimate was an underestimate.
In addition, a report by the National Oceanic and Atmospheric Administration suggests that females of the endangered North Atlantic right whale species are producing fewer offspring due to stress and injuries from repeated entanglement in fishing gear.
Old observations can still teach something new
Although Ouarbide is no longer researching whales and her comments in the study are several years old, Trites said her research is still helping the scientific community because it offers a glimpse of past whaling behavior in Canada that can be compared to Can be done with data from other parts of the country. Worlds like Africa, China and Australia.
“I learned something I didn’t know before,” said Trites, who has been studying marine mammals for more than 30 years. “I know about sperm whales being linked to different fisheries, but I didn’t know that northern bottlenose whales show similar behavior, so I learned something new.”
“The study tells us how whales can exploit new resources, plus, sometimes with really good data, we can get a better understanding of how they interact with each other,” Whitehead told Insider. how to learn new behavior.
Oyarbide said his coauthors are using the study’s data to better understand the hunting of bottlenose whales in Canada, which may be under-reported.
Source: www.bing.com
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