New discoveries about basking sharks blow assumptions out of the water

Basking shark larvae south of Malin Head, Ireland.Credits: Emmett Johnston, Queen’s University Belfast

If basking sharks are like Canadians, their travel habits can be easily explained. Head south to avoid the cold of winter and head north again to enjoy the warmth of summer.

Basking shark turns out to be a more complex puzzle. Western biology professor Paul Mensink and his colleagues discovered it while investigating the seasonal movements of giant fish.

Mensink and fellow researchers at Queen’s University Belfast in Northern Ireland track and winter four sunbathing sharks (large enough to reach the size of a school bus) from the northernmost tip of Ireland. I investigated the reason.

They tagged it to record the location of the shark along with the water temperature And depth.

“They were supposed to swim in the coastal waters of Ireland in the summer and south in the warm winters because they have a really productive feeding ground. Initially, the water temperature triggered them to leave. I thought it should be, “said Mensink.

“They have blown our assumptions out of the water.”

Two of the four sharks that surprised the researchers remained.

The other two, as expected, moved south to tropical and subtropical waters off the coast of Africa.

But instead of relaxing there in the warm waters, these two spent more time in deeper and much colder water than if they stayed near Ireland.

Early each morning, these sharks dive to a depth of 200 to 700 meters, return near the surface near noon, and sink to chilly depths in the evening.

“It was like a clockwork,” said Mensink, a marine ecologist who specializes in educational technology and is an educational fellow at the Faculty of Western Sciences. “It’s like a diving pattern for animals that have to rise to the surface to breathe air, but of course it’s not.”

During the dive cycle, sharks are placed in extreme water temperatures. It is 27 degrees near the surface of the water and 7 degrees near the surface of the water. depth..

So why do rational and cold-blooded creatures do it?

New discoveries about basking sharks blow assumptions out of the water

A pair of basking sharks in the Irish Inishtrahull sound.Credits: Emmett Johnston, Queen’s University Belfast

“In the end, I think they’re going to eat what they call the deep-sea scattering layer, which is packed with gelatinous zooplankton and other things,” Mensink said. .. And at noon, as their name suggests, they rise near the surface to bathe in warmth.

Sharks, on the other hand, staying in shallow water near the Irish coast did not experience extreme cold or warmth, as winter water temperatures ranged from 9 ° C to 17 ° C.

Unlike offshore sharks, stay-at-home sharks had little change in depth during the six months in which the four animals were followed.

Their newly published research is published in the journal Environmental biology of fish..

Mensink’s team does not yet have an answer as to why the two stayed longer and the other two swam south.

Jonathan Houghton of Queen’s University Belfast, co-author of the study, said:Reluctantly go out Ocean If you lower the water temperature, the water temperature will be forcibly lowered. “

The findings remind us that studies of marine habitats and marine animal habitats must include both depth and distance, Mensink said. “We must think of the sea as a three-dimensional place.”

One of the key lessons of the study is that conservation of deep-sea habitat is essential for the survival of the organism, said Emmet Johnston, a researcher at Queen’s University Belfast, the lead author of the study.

“Similarly, further evidence of individual basking sharks occupying Ireland Coastal waters It has a great impact on national and European conservation activities throughout the year. ”

Basking sharks are the second largest fish in the ocean (after whale sharks) and use their huge mouth and gill raker to filter and feed small organisms such as zooplankton. They are considered vulnerable species worldwide.

In Canada, it is designated as an endangered species off the Pacific coast.

The team works with basking shark sunbathing as part of a major EU SeaMonitor and works with partners in Ireland, Northern Ireland, Scotland, Canada and the United States to develop a variety of marine life mass conservation strategies. ..

Education and research of Mensink Basking shark Includes plans to take Western undergraduates to the sea of ​​fish Habita Through the March Augmented Reality app, they will effectively immerse themselves in the marine ecosystem and “swim” by creatures.

Relief of sharks found in cross-conformation

For more information:
EM Johnston et al, Cool Running: A Realized Thermal Niche of Behavioral Plasticity and Basking Sharks, Environmental biology of fish (2022). DOI: 10.1007 / s10641-021-01202-8

Quote: A new discovery (February 10, 2022) that basking sharks blow assumptions from water from https: // on February 10, 2022. It was acquired.

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New discoveries about basking sharks blow assumptions out of the water

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