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Diver encounters 23 sharks in one spot: Why they're converging

STUNNING: A dive at Rainbow Beach's Wolf Rock on the weekend gave divers an up-close encounter with more than 20 sharks.
STUNNING: A dive at Rainbow Beach's Wolf Rock on the weekend gave divers an up-close encounter with more than 20 sharks. Carl Charter- carlcharter.com.au

UNSEASONABLY warm waters and recent rain mean the chances of a shark encounter on the Sunshine Coast are still fairly high.

Marine education expert Tony Isaacson said unusual water movements as a result of eddy currents pushing north from the south-moving East Australian Current were bathing the Coast in unusually warm waters.

That often led to a spike in algal blooms, which fed plankton, small fish and sardines which attracted mackerel and tuna.

When those bigger fish arrived, so too do the apex predators, often in the form of tiger sharks and manta rays.

Mr Isaacson believed the unusual occurrences were possibly down to a shift in broader weather patterns, as the region transitioned from a wet few years to a drier, El Nino pattern.

But out of season rains like last week's were also a trigger for 'local' bull shark activity.

At the end of their breeding season, Mr Isaacson warned bull sharks present at the moment would be actively hunting, and more likely to bump or bite first "and ask questions later".

He warned locals to be careful in canals and waterways following the recent rains, as visibility had been reduced.

 

It's not just bull sharks that the conditions have affected.

A weekend dive at Wolf Rock, off Rainbow Beach, left Mr Isaacson face-to-face with 23 endangered grey nurse sharks at the popular dive site.

Mr Isaacson said about half a dozen manta rays had also been sighted during what was a crystal-clear dive.

"I have never encountered 23 grey nurse sharks in the one spot on the one rock," he said.

"We didn't expect to see six manta at Wolf Rock the other day either, but six manta is what we got."

 

STUNNING: A dive at Rainbow Beach's Wolf Rock on the weekend gave divers an up-close encounter with more than 20 sharks.
STUNNING: A dive at Rainbow Beach's Wolf Rock on the weekend gave divers an up-close encounter with more than 20 sharks. Carl Charter- carlcharter.com.au

He believed the spike in grey nurse numbers at Wolf Rock was down to a combination of factors, including seasonal variability and lucky timing, with two groups of sharks converging on the site.

Mr Isaacson said tiger shark sightings may reduce now around local surf zones, as loggerhead turtle nesting has wrapped up, but there was still plenty of food for the predators around Old Woman Island, and warmer waters favoured tiger sharks.

He advised awareness when out at Old Woman Island, given the amount of food source there for any interested sharks.

He believed an increase in the number of tiger shark sightings last summer was due to an increase in turtle nesting in the region, and noted Rainbow Beach had some of the highest numbers of tiger shark catches in the State Government's shark control program.

Two hundred and seven tiger sharks were caught across the state as part of the control program last year, with 17 of those caught off Rainbow Beach, the biggest a whopping 3.95m tiger shark.

A string of tiger sharks were caught off Coast beaches in October last year, with two caught off Noosa on the same day, while a 3.76m tiger shark was caught off Coolum in late October.

Eleven bull sharks were caught off the Sunshine Coast last year, while three were caught off Rainbow Beach.

Topics:  animals community diving environment lifestyle marine biology marine life nature offbeat recreation sharks sunshine coast weather



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