How Many Sharks Are There?

6 Feb 2019 32 Share

Nick Carroll

Senior Writer

Photo: YouTube/PanasonicEUBatteries

Photo: YouTube/PanasonicEUBatteries

COASTALWATCH | NICK CARROLL

Sydney to get SMART — but what will it tell us?

Maybe you have one of the shark apps. They make your phone go “ping!” all day and night, telling you about sharks.

The shark app goes “ping!” partly because it is tapped into 85 or so SMART drumline shark-catcher buoys along the NSW coast.

If, like me, you live in Sydney, you might have noticed your phone has almost never gone “ping!” anywhere around Sydney.

That’s because there have never been any SMART drumlines off Sydney.

Well all that is about to change. On February 11, that’s next Monday, the NSW Dept of Primary Industries will drop a series of SMART drumlines into waters off Sydney’s northern beaches.

Specifically: Palm Beach, Whale Beach, Avalon, Bilgola, Newport, Dee Why, Curl Curl, Freshwater, Queenscliff, North Steyne and Manly.

Yep! Finally your phone will tell you when a threatening shark species has been captured directly off some of the nation’s most populated beaches!

One can hardly wait for the media response.

But what are these pings telling us about the bigger questions? The ones raised during the infamous attack cluster on the NSW north coast three years ago, that led to all the shark apps and political holy-shit and SMARTness in the first place?

You may have read about the recent Southern Cross Uni marine wildlife tracking study. The study used drones at various times over two years to survey inshore wildlife along the north coast. It found a lot of wildlife, but says it saw very few sharks.

This is probably because the sharks are further out.

SMART drumlines are set 500m or more offshore and operate solely during daylight hours. They are designed to catch “target species”, ie whites, tigers and bulls, but are not designed to attract them — just to pick 'em up if they're cruising by. The sharks are then tagged and released a bit further offshore.

Three-hundred-and-seventy individual target species of sharks have been caught, tagged and released on them in NSW waters in just under three years. Three-hundred have been white sharks, 43 have been tigers, and 27 bulls.

It’s when you start heading down into those raw figures that maybe one of the questions – why that terrible attack cluster happened –finds its way toward answers.

For instance: 52 of those white sharks, over one sixth of the entire catch, have been caught during just TWO MONTHS, July 2017 and July 2018, in ONE AREA, off Lennox/Ballina and Evans Head – the same area surveyed by the Southern Cross Uni team.

This just happens to coincide with the annual northern humpback whale migration, which comes in close to that part of the coast at that time.

How about that folks? When there’s lots of whales, there’s lots of sharks!

And maybe some years, when the whales go away, the sharks hang around.

Here’s another thing: The SMART catch rate has remained consistent throughout the three years, and may even have increased. For instance, 26 new whites and three new tigers were caught off Le/Ba/Evans in the last four months of 2018. This is pretty much right on the average for the whole coastline.

This suggests we’re a long way from exhausting the supply of available tag-ees – which should not be a surprise. After all there’s only been 85 drumlines along 2000-plus kilometres of coast. And they’re only set during the day. And only when the weather isn’t hectic.

So how many of the total number of whites and tigers and bulls have we tagged, do you reckon? Five per cent? Ten? Less? More?

There’s no way to tell, is there?

Therefore the answer to the Big Question, how many sharks actually are there, stays pretty much the same:

A: Nobody fucken knows.

Enjoy the next few months of pings.

Read about the drumlines here


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