Shark attack data

 While I was bored a little while ago I put these graphs together.  They are based on recorded all recorded shark attacks in WA.  There are two graphs - one for all shark attacks, and one for fatal attacks.  Notes on reading the graphs:

1.  The green line is total population, read off the left side axis.

2.  The yellow bars are the number of attacks in each year, read against the right side axis.

3.  The blue line is the rate of attacks in that particular year, calculated as number of attacks per million population, read against the right side axis.  This is meant to normalise for population growth.

4.  The red line is the 10 year moving average of the blue line, read against the right side axis.

5.  This data does not have any species information.

6.  The fatal attacks are a subset of the total attacks i.e. the total attacks includes fatal attacks.

 

A couple of things that they point out to me:

- historically, the rate of total attacks is fairly consistent, although we appear to be in an upswing, but not significantly higher than past peaks.

- there has been a large increase in fatal attacks since the early nineties.

 

**UPDATE - added marker on graphs to show when GWS were protected in the late '90's.***

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so in a nut shell based on

Tue, 2018-04-17 13:22

so in a nut shell based on your graphs since the GWS was protected circa 1999/2000 the rate of attacks has been steadily increasing.

Daryn's picture

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 I am not sure the

Tue, 2018-04-17 13:54

 I am not sure the correlation between population and attacks should be considered in a linear fashion. If a hungry white comes along and there are 100 times more people, it can still only eat one of them. 

 

Yes, there may be people in the water in places they never were, but this explains a small increase, not the large one we see now.

 

 

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Possibly

Tue, 2018-04-17 14:45

I don't have any insight as to the reasons why the increase. 

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Auslobster's picture

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Percentages....

Tue, 2018-04-17 18:41

 ...in 90 years, the WA population has increased 5X (500%). But what is the percentage increase of WATER USERS? I'm guessing, over that 90 year period, it's way more.

 

Surfing was invented in the early 1900s by the Hawaiians...and didn't become mainstream around the world (and WA) for many years. SCUBA diving wasn't invented until the 50s, and I doubt the average Joe Bloggs was doing that with any frequency until at least the 60s/70s. Probably safe to assume that snorkeling wasn't hugely popular until later in the century, too.

 

Point is, yes more people in WA, but of those people, an even higher number entering/using the ocean than even just 30/40 years ago.

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Good point

Tue, 2018-04-17 19:19

I’d also bet more people diving for crays and spear fishing.

 

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sea-kem's picture

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 I saw it through the early

Tue, 2018-04-17 19:32

 I saw it through the early 90's where SCUBA became more affordable for the average punter and dive shops were popping up everywhere. In my class where two Japs who couldn't even swim lol. 

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 It's a numbers game or so i

Wed, 2018-04-18 16:43

 It's a numbers game or so i thought until I read that acting fisheries head honcho mr cook say that drumlines were a indescriminate way of killing sharks to make the public think there are less sharks in the water. excuse me but i thought if you kill one shark then yes there is one less and the only way to reduce shark attacks is to reduce the number of sharks if there is a attack and more than one shark is take from the area i would call that a bonus 

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Whales and seal numbers

Wed, 2018-04-18 18:22

Add humpback whale and seal numbers to the graph and see what that brings.

 

As someone who has spent years at sea and one notices the huge increase of whale numbers heading up and down the coast since they stopped commercial whaling to what they are now plus the growth in seal numbers in the same period. One example is the colony on Cape Naturaliste, go back 15 years and there wasn't a colony there yet a mate told me not long back that he has seen up to 40-50 there on good days.

 

Allright a whale carcass washes up on a beach and the media say it attracts sharks to the area, well bugger me dead, how long has it been floating out there attracting them. The media are the main cause of all the histeria from these attacks. Go back to when Ken Cruse? got his leg bitten off at Cottesloe beach, we had Rory Mc Cauley from Fisheries shark research on board at sea out of Port Hedland and when we heard of the attack he was dreading coming in to phone range because of all the media attention that he was going to receive.

Auslobster's picture

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So basically...

Wed, 2018-04-18 20:49

 ...if there are more people in the water, and more prey (whales), and attacks increase, the solution is to kill more sharks?

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GPS

Thu, 2018-04-19 20:13

 So where on that graph would the introduction of cheap accesable GPS come into it? I dont own a boat but have many mates that do and when i go out with them i look at their screens and see multiple marks that give the exact location of where they have caught fish. Im not a greeny but  im smart enough to know that if you take away a predators food source it will go look elsewhere, those 2 attacks occured where there was a dead whale in the area and the second attack the dickhead knew that sharks were in the area but he chose to go out anyway, its a shame stupid cant be a crime. As i write this on the news they are reporting about a car crash with multiple people being injured, but im sure in the morning you and i will get in the car and not give a second thought that there is a possibility that you/i can be involved in a crash, maybe even a fatal one. And i love how the government agency involved decided to tow the whale carcass along the shore line instead of taking it kilometres offshore, thus taking any sharks that were attracted to the area away and out of possible harm to anyone in the water, just my opinion and im sure many will disagree but hey, just like you, my opinion is the only one that matters to me

 

sea-kem's picture

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 You sortta lost me with your

Thu, 2018-04-19 21:26

 You sortta lost me with your first statement about GPS and catching fish from a certain location That correlation is a load of shit imo, just my opinion. 

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