Why sharks like it hot - but not too hot

From BBC - March 12, 2018

Scientists have calculated the water temperature at which tiger sharks are most active and abundant.

They say the sharks, which are second only to great whites in attacking people, prefer a balmy 22C.

Shark populations may shift range as the oceans heat up, bringing them into greater conflict with humans, according to the scientific study.

For instance, tiger sharks may move into waters off Sydney in both winter and summer months.

Dr Nicholas Payne of Queen's University Belfast and the University of Roehampton led the research.

"Our study suggests that 22 degrees is not too cold for the animals and it's not too hot for them," he said."It's about right in terms of their optimal preference for temperature."

Cold blooded

Most sharks are cold blooded. Their body temperatures match the temperature of the water around them.

The research, reported in the journal Global Change Biology, could lead to new ways to predict when and where tiger shark attacks might happen.

Increases in coastal water temperatures of one or two degrees could lead to a southern shift in the population of tiger sharks.

"At the same time places like Sydney might start to see more tiger sharks during winter months whereas at the moment you very rarely see tiger sharks in Sydney in winter," Dr Payne added.


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