Great White Shark Attack Paddle vs Pedal Numbers

[PAL]

After the recent great white strike on two Hobies, a lot of people blamed the pedal drive. I wanted to see for myself how the numbers stack up. I've kept pretty good records of all the white shark on kayak strikes in California since the first attack on an angler in 2007. It was time for an update anyway.

Give it a look. Since 2007, the score stands at 7 paddlers vs. 5 pedalers. If we limit it to kayak anglers only, it's 5 pedalers and 4 paddlers. That leads me to believe it doesn't matter what you drive if you come across an aggressive shark at the wrong time. In case you're interested, there have been 17 great white attacks on kayaks since 1989, far fewer than on surfers and swimmers. Of those 17 incidents, two fatalities are more or less documented. Otherwise injuries are incredibly rare.

Since I posted these numbers in a story for Kayak Fish Magazine, many people have rightly pointed out that it would be instructive to compare the raw attack numbers vs. the proportion of each kayak type.

Until kayak manufacturers and dealers release that closely guarded information, we're at the mercy of on the water observation. Of course the proportion varies across the state.

Completely subjectively, on a typical day Hobies outnumber paddle kayaks by at least 3 to 1 at La Jolla. In a Facebook post Jason Self put the number about the same up in Trinidad, 3 Hobies for every one paddle kayak, but he was talking about anglers (I think).

Scroll down for that great white shark attack on kayaks in California listing I compiled. I attached it so you can all download it if you like. I invite you guys to take the data apart, all of it, not just the paddle vs. pedal question. Any statisticians here?

I'm also looking to fill in a couple blanks on the spreadsheet and for additional information such as water clarity, whether anglers had fish on board (personally I don't think it matters), if they were using sonar at the time, etc.

Here's the most pertinent part of my story for Kayak Fish Magazine:

Check out the chart beginning with the tragic case of Tamara McAllister and Roy J. Stoddard, who were presumably killed by a great white strike off of Malibu’s Paradise Cove in 1989. We could tally paddle versus pedal statistics from there (it’s 12 paddle, 5 pedal if you must know), but it wouldn’t make any sense. Hobie’s Mirage Drive wasn’t introduced until 1997. Another decade passed before a great white shark hit one of the company’s kayaks. Let’s start there.

Back to Dan Prather, whose red Adventure was the first Hobie attacked. The next two kayakers to feel the heat (both in 2008) were paddlers, recreationalist Bettina Pereira at Catalina and sea kayaker Tony Johnson off Tomales Head.

2009 was a quiet year, but August 2010 was tough. Adam Coca was hit hard at Bean Hollow, and a great white mouthed the bow of Duane Strosaker’s sea kayak offshore of Gaviota (yes, his legs were inside the shark’s mouth, inside his boat), a couple of particularly harrowing incidents. Both paddlers. If you’re keeping score at home, that’s one pedal kayak and four paddle kayaks since 2007.

From there, it’s neck and neck between the two propulsion types. Harry Pali was pedaling off Pigeon Point when his kayak was hit in 2011. Joey Nocchi was paddling off Leffingwell Landing the next year. Mel Camu was pedaling; Micah Flansburg and an as yet unidentified man related to a kayak angler known only by the handle FlyYaker both paddled. That takes us up to the Vandenberg duo, who both pedaled.

If you kept up, you already know the score since 2007 stands at 7 paddle, 5 pedal – all of the flipper variety. Prop-style pedal drives are relatively rare on western saltwater. None have been hit by a great white. Counting anglers only, the numbers swing to 5 pedal, 4 paddle. Inconclusive? From here it looks like what you drive isn’t the determining factor.

Here's the link to the entire story: http://www.kayakfishmag.com/features...r-great-white/

[flemdogg]

Informative, in depth, and very interesting. Thank you for the info.

[YTHunter]

Went out at LJ yesterday... no one for miles around.

Anyway, wonder if/how kayak color factors in.

[FISH11]

Same here. It was super hard to make any bait. So I trolled a rapala, not much fun trying to avoid the lobster trap buoys and the floating cut up kelp. No hits and finally found some spanish late and went deeper to try some more. Just lost 3 in a row to the knucklehead dogs. trolled and drifted for a couple more hours and nothing. After finding the bait late I did see some bait jumping so I threw a surface iron, but nothing. Was on the water from 8am to 5:30 with no luck. Still had fun drinking beer and enjoying the sights on a very calm day.

[blitzburgh]

Good stuff Paul!

[pbb]

As someone with a stats background (Ph.D. in Sociology with a quantitative focus, M.A. in Demography), I would agree that there is nothing here that suggests any conclusive "statistically significant" differences by propulsion method.

The OP is correct that you would really need to know how many people are out there in these types of kayaks at risk of getting attacked to do the analysis correctly.

In fact, you would ideally need to know not only what kind of kayaks are out there in consumers' hands, but how much they use them. In other words, if you had 1000 people with Hobie mirage kayaks and 1000 people with paddle kayaks, and the mirage drive kayakers spend twice as much time on the water as people with paddle kayaks, you would expect them to experience twice as the number of shark attacks even if the rate of shark attacks was exactly the same.

[PAL]

Originally Posted by pbb

As someone with a stats background (Ph.D. in Sociology with a quantitative focus, M.A. in Demography), I would agree that there is nothing here that suggests any conclusive "statistically significant" differences by propulsion method.

The OP is correct that you would really need to know how many people are out there in these types of kayaks at risk of getting attacked to do the analysis correctly.

In fact, you would ideally need to know not only what kind of kayaks are out there in consumers' hands, but how much they use them. In other words, if you had 1000 people with Hobie mirage kayaks and 1000 people with paddle kayaks, and the mirage drive kayakers spend twice as much time on the water as people with paddle kayaks, you would expect them to experience twice as the number of shark attacks even if the rate of shark attacks was exactly the same.

Great stuff! I'd like to quote you in an update to the original story. Please PM your name, and add any other statistical observations you'd care to share. Maybe something about the relatively small sample size?

[da22y]

Originally Posted by YTHunter

Went out at LJ yesterday... no one for miles around.

Anyway, wonder if/how kayak color factors in.

I was out in LJ yesterday too, 5 feet long hammerhead shark circle my yellow Hobie revo more than 3 times, I had my home make kage at hand , finally I smash my fishing pole on the water very hard, and the hammerhead shark dart away...

The shark look at me eyeball to eyeball, very scary moment...

[jruiz]

I just had to

[PAL]

Originally Posted by YTHunter

Went out at LJ yesterday... no one for miles around.

Anyway, wonder if/how kayak color factors in.

Since you asked...

I also broke down the attacks by kayak color. They span the spectrum. I'm sticking with brighter colors such as orange and yellow. Boaters are the greater danger.

Lame chart attached below. If sharks are color blind as one researcher discovered (I'm not sure about great whites), then contrast could be the crux of the matter. If that's the case and we're really looking at brighter kayaks vs. darker the chart could be read as 7 light vs. 4 dark, although I'm not sure of the actual shade of some of those reported colors.

The story in case you want to read it: http://www.kayakfishmag.com/features...olor-question/

[chris138]

The variable that sticks out to me are the dates of attacks. It appears that an attack has become significantly more likely in the last 4-5 years. That could be a function of more people being on the water kayaking, or perhaps an increase in GWS population as a result of more modern conservation efforts.

[GregAndrew]

Originally Posted by PAL

Great stuff! I'd like to quote you in an update to the original story. Please PM your name, and add any other statistical observations you'd care to share. Maybe something about the relatively small sample size?

I said essentially the same thing as a comment on the page the article appears on. It is the total number of hours spent in the "Zone" by the different types of kayaks divided by the number of attacks on each. That will give you the attacks per, probably, hundreds of thousands of hours in the "Zone".

Sample size is not a term that applies here. What you have is a small number of occurrences. Sample size is the number of data points that you survey in order to make a prediction about a population. Like the number of Hobie owners you question in order to find out if they have been attacked by a shark.

[PAL]

Originally Posted by GregAndrew

I said essentially the same thing as a comment on the page the article appears on. It is the total number of hours spent in the "Zone" by the different types of kayaks divided by the number of attacks on each. That will give you the attacks per, probably, hundreds of thousands of hours in the "Zone".

Sample size is not a term that applies here. What you have is a small number of occurrences. Sample size is the number of data points that you survey in order to make a prediction about a population. Like the number of Hobie owners you question in order to find out if they have been attacked by a shark.

I hear you, but who has the time (or the data) for that?

That is likely why the risk of suffering a shark attack is typically expressed in terms of the overall population. For instance, you have a better chance of getting killed by a falling coconut than you do a shark... blah, blah, blah. That's no help other than in simplistically illustrating the low overall occurrence of death by shark.

Someone who never dips a toe in the ocean has no chance of succumbing, not even if they are Austin Powers (just maybe if the sharks have fricken laser beams).

Life is one big judgement call.

[GregAndrew]

More than the color of the kayak, I would like to know the visibility of the water at the surface in each instance. If it is generally less than say 15' (at the speeds they are probably traveling) then you might infer that the sharks are attacking a silhouette more than anything else. That could also cloud the data if the sharks can't tell until last second that a Hobie has fins. However, if the sharks are seen before the attack or the water is generally very clear, then all bets are off on that.

[GregAndrew]

Originally Posted by PAL

I hear you, but who has the time (or the data) for that?

That is likely why the risk of suffering a shark attack is typically expressed in terms of the overall population. For instance, you have a better chance of getting killed by a falling coconut than you do a shark... blah, blah, blah. That's no help other than in simplistically illustrating the low overall occurrence of death by shark.

Someone who never dips a toe in the ocean has no chance of succumbing, not even if they are Austin Powers (just maybe if the sharks have fricken laser beams).

Life is one big judgement call.

Sharks don't have laser beams? Sorry, my pet peeve is people using data as statistics, especially politicians and environmentalists.

[PAL]

NCKA poster Northern Boy posted this. I think he's right. If all attacks had involved Hobies or none had, the trend would be convincing:

I'm not so sure about that. Statistics is an exact science, but the design and interpretation of statistical tests is not.

There are a lot of factors to be considered in the latter - the importance of those depends on the strength of the effect - to give a simplistic example - if the 12 attacks had all been on Hobies, then I don't think anyone would be worrying about whether Hobies spend more time on the water or what color they were.

However, as it is, the descriptive statistics available are indeed pretty muddled (I had not seen those before, they are very informative) and thus the small sample size is a problem, as are the other, potentially confounding, factors like the number of Hobies vs paddle etc. Hopefully not a 'problem' that will be fixed anytime soon.

NB

[pbb]

I agree you have a limited number of occurrences. Most likely it is the full universe of occurrences (at least for recent years). And this is different from the sample size. I'm working on a study of occupational injuries where about 13000 people were screened for (asked about) occupational injuries and less than 200 such injuries were identified. You sample size in that case is the 13000.

Here again, we really don't know how many hours people are spending on the ocean, so we have neither a sample nor a denominator for a rate of attacks.

But given that you have a similar number of occurrences, you would have to believe that the hours spent at risk (i.e., on the ocean) by the two groups was very different to conclude that you might have a higher risk for one group.

My sense (and here we depart from anything statistical or scientific) is that there aren't orders of magnitude lower person hours spent in Hobie Mirage kayaks on the open ocean compared to paddle kayaks, hence I don't see anything in the data that I would find to be convincing that there is a difference.

It wouldn't be scientific, but you could try to get a sense by creating a "poll" on various California kayak fishing forums about how many hours users fish or kayak in the ocean during an average month in mirage drive or paddle kayaks. That might give some more information, but it wouldn't be conclusive since it would be a convenience sample rather than a probability sample of kayak anglers. But I can't think of any feasible way of doing the latter, except possibly asking DFG to add that to their CRFS survey when they survey kayakers. (I guess you could ask DFG to let you do a mail or email survey to everyone with a fishing license and and ocean stamp, if you had a lot of money to burn).

[pbb]

BTW, it's not sharks with laser beams you should worry about if you are not in the ocean, it's the sharknados.

[PAL]

Originally Posted by pbb

BTW, it's not sharks with laser beams you should worry about if you are not in the ocean, it's the sharknados.

You're right! That's scary stuff.

[GregAndrew]

Originally Posted by pbb

My sense (and here we depart from anything statistical or scientific) is that there aren't orders of magnitude lower person hours spent in Hobie Mirage kayaks on the open ocean compared to paddle kayaks, hence I don't see anything in the data that I would find to be convincing that there is a difference.

I would wager that there were and still are magnitude differences in the numbers. Even in local SoCal markets, where Hobie does very well, they do not represent half of the kayaks or hours on the water. LJ might be the only notable exception to this, but only if you only consider fishing kayaks and not rentals. And the further you go back toward the inception of the Mirage drive, the larger the difference is going to be.