Marine Biologist reveals how to redirect a tiger shark

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Researchers have sounded the alarm after a study showed the migration pattern for tiger sharks – second only to great whites in recorded fatal attacks on humans – are moving northwards. They believe it is attributed to climate change. Experts warn they are now more vulnerable to interactions with humans and commercial fishing as they move out of protected areas.

The team, from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, say the location of tiger sharks is shifting due to rising ocean temperatures.

Tiger sharks are the largest cold-blooded apex predator and need to stay in warm waters.

Waters away from the US northeast coastline have historically been too cold for tiger sharks, but temperatures have warmed significantly in recent years.

In UK waters, mean annual sea temperatures have risen by 0.8C since 1870, and have shown a consistent warming trend from the Seventies onwards.

Study lead author Professor Neil Hammerschlag, director of the UM Shark Research and Conservation Programme, said: “Tiger shark annual migrations have expanded poleward, paralleling rising water temperatures.

“These results have consequences for tiger shark conservation, since shifts in their movements outside of marine protected areas may leave them more vulnerable to commercial fishing.”

The team found the climate-driven changes by analysing nine years of tracking data from satellite-tagged tiger sharks.

It showed that, during the last decade, for every one-degree Celsius increase in water temperatures above average, tiger shark migrations extended farther poleward by roughly 250 miles and sharks also migrated about 14 days earlier to waters off the US coast.

The results may have greater ecosystem implications, according to the researchers.

Prof Hammerschlag added: “Given their role as apex predators, these changes to tiger shark movements may alter predator-prey interactions, leading to ecological imbalances, and more frequent encounters with humans.”

The findings were published in the journal Global Change Biology.

It comes as new research from LSU and the University of Florida suggests that more shark attacks occur during fuller phases of the Moon.

While the exact cause remains unclear, the researchers found that more shark attacks than average occur during periods of higher lunar illumination and fewer attacks than average occur during periods of lower illumination.

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Many different types of animals show behaviours that are linked to moon phases yet few studies to date have looked at the connections between lunar phases and shark attacks.

Although sharks rarely bite humans, the tiger shark is reported to be responsible for a large share of fatal shark-bite incidents, and is regarded as one of the most dangerous shark species.

They often visit shallow reefs, harbours, and canals, creating the potential for encounters with humans.

The tiger shark also dwells in river mouths and other runoff-rich water.

While the tiger shark is considered to be one of the sharks most dangerous to humans, its bite rate is low.

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