Monday, April 15, 2013

The Cretin's Guide to Commercially Killing Sharks

Don't get me wrong I am all for shark research. Having personally sponsored at least one ground breaking shark project for a number of years at Isla Guadalupe anyone who knows me knows I love fresh shark data.

But when does widely available shark data become a road map for commercial shark harvest?

In the hands of commercial fishermen who read english and who have access to basic Internet, it would seem the last secrets of many sought after shark species are now available to just about anyone.

Case in point my email box was hit with this recent report from Live Science that read Sharks Dive Deep Under Full Moon:

"Over the course of nearly three years, researchers from Australia observed 39 mostly female grey reef sharks (Carcharhinus amblyrhynchos) living near coral reefs in Palau, Micronesia, east of the Philippines. In the winter, the sharks stayed closer to the surface, at an average depth of 115 feet (35 meters), where water was consistently warmer, the team found. Meanwhile, the sharks plunged deeper in when seasonal temperatures started rising in the spring, averaging depths of 200 feet (60 meters)."

Wow, really?

Alright, so if I am a shark fishing boat, and I happen to be in and around coral reefs in Palau, Micronesia, and east of the Philippines (not north, south or west) all I have to do is set my hooks to 115 feet and clean house?

Oh, and when water temps rise drop them to 200?

Conservationists who have never worked a long line vessel (I have) have no idea that data like this often means the difference between a full hold and nothing at all. I might even posit the fact that some sets occasionally come back empty are the sole reason why some shark species have remained protected in certain high traffic areas.

Hooks were set too shallow or too deep and sharks survived.

Fact is fishermen do not have the financial incentive to reset and reset and reset on areas based on hunches that key note species might be available to them. They go with what they know, set and hope for the best.

Once though a species is "dialed in" you know where, when, and how to harvest them, there's nothing saving these critters from total annihilation. Word gets around quickly in the fishing community and data like this is a road map...treasure map is more to the point.

So it remains an open question, is the wholesale release of shark data good or bad for shark species?

I am 45 years old, I have lead an extraordinary life and seen far too much of humanity to believe for one instant that a commercial fishing boat would "do the right thing" and not capitalize on any specific data that gave them the back door to a key note species castle.

Sadly, life is not as altruistic as this, and it is high time this issue was addressed by the larger shark research community. Setting up firewalls with data would be an easy thing to do. The only thing missing in this equation is the desire and leadership.

Note: I have suspicion these sites may or may not be located in and around Shark Sanctuaries. Da Shark will be pointing that out shortly. I also have a dim view on sanctuaries that do not also feature robust enforcement. That debate will play out over the next decade. Irregardless, specific depth, time and location data for target sharks just makes the desire to run a sanctuary even more enticing when you know your full hold is just 115 feet away.


Patric Douglas
Shark Diver
Currently enjoying semi-retirement

About Shark Diver. As a global leader in commercial shark diving and conservation initiatives Shark Diver has spent the past decade engaged for sharks around the world. Our blog highlights all aspects of both of these dynamic and shifting worlds. You can reach us directly at


Angelo Villagomez said...

I'd argue that fishermen already know this and the researcher could have saved a lot of time just by looking at some log sheets. S/He'd probably have come to the same conclusion.

Angelo Villagomez said...

BROMHEAD, D. & CLARKE, S. & HOYLE, S. & MULLER, B. & SHARPLES, P. & HARLEY, S. 2012 Identification of factors influencing shark catch and mortality in the Marshall Islands tuna longline fishery and management implications. Journal of Fish Biology, in press

Shark Diver said...

If you want to know EXACTLY what is happening in the shark community call Angelo.

Sir, you are a fountain of sharky information.

DaShark said...


The paper in question is about vertical movements of Grey Reef Sharks, not a species commonly caught, let alone targeted by long liners.

Angelo, did you actually read the paper you cite?
Very much unsurprisingly, it reports a whopping 4 (four! caught and discarded Grey Reef Sharks - hardly the N for reaching any conclusions about where/when to set lines!

Long story short?
Interesting thoughts - wrong species!

Shark Diver said...

Wait a second....according to the Wiki and other sources:

"They are caught in many fisheries and are susceptible to local population depletion due to their low reproduction rate and limited dispersal. As a result, the International Union for Conservation of Nature has assessed this species as Near Threatened."

Granted not your flashy OWT or CITES Porbeagle (Lamna nasus) and mostly inshore long line or localized fisheries for now but - on the radar for sure.

What happens when species are harvested to the brink? The fishery continues they just step it down a species. Always.

My point is valid and instead of actually pointing out the most recent case of research shark media euphoria that might or might not have caused the loss of an entire breeding stock, you probably know of what I speak, if not I won't be your Judas Blogger on THAT one.

I think there's a strong case for some sort of self censoring, or knowledge that the conservation community are not the only ones who can read.

If I had the time and inclination that being of a man who is, as you well know, semi-retired, I am sure I could come up with many examples of papers that create a fisheries road map to the shark promised land.

It's an issue.

As far as this study is concerned the one I cited 39 sharks is enough to make a case for long lines commercial or inshore and if you read this article:

"In places such as Palau, which relies heavily on marine tourism and where sharks are a major tourist attraction worth $18 million a year, the fishing of a few dozen sharks from popular dive sites could have a very negative impact on the national economy," Vianna explained. "This is potentially a big concern because it could happen in just a couple of days." WHY does this report give away time, depth, location, and moon phase?

Meh, 3800 blog post, 1.9 million page views, and I'll take a double play on this one.

Shark Defenders said...

Yes, I read the paper. I was pointing toward the fact that fishermen know how to catch sharks in general, not necessarily the moon phases of grey reefs. Sorry for the misunderstanding.

Shark Diver said...

And good points too Angelo, I had not considered that research data may in fact be sub par to good old fashioned fisheries data.

Still a big fan.

DaShark said...

As I said, interesting thoughts! :)

Yours truly about the risk of publishing tracks here.

As always in science, the data can be used for good or bad purposes.

Shark Diver said...

Making you the better shark blogger, scooped again.

If it wasn't for that nifty period wood cut shark image I might not have been inspired to blog in the first place;)

DaShark said...

Nah nah - yer still the undisputed numero uno! :)

Just keep them coming buddy - being semi-retired is precariously close to being semi-retarded, and we sure want none of that!

Shark Diver said...

Semi-retired = semi-even less interested in the inane goings on out there by a host of Special Shark People.

Of course you already know this;)

As Socrates once said,"Nihil sub sole novum Michael Neumann"

DaShark said...

... and I betcha he didn't!

- because he was Greek not Roman

- because I learn that nihil novi sub sole is a vulgate translation at Ecclesiastes 1:10, from the Hebrew אֵין כָּל חָדָשׁ תַּחַת הַשָּׁמֶשׁ (en kol chadásh táchat hashámesh)

Detail detail - just like those Grey Reefs! :)

Gabriel Vianna said...

Hi Patric,
From the time I’ve spend doing research on long-liners in the Atlantic and from what I’ve seen patrolling for them in the Pacific and Indian Ocean, fishermen do not set lines randomly just hoping for the best. More often them not, they know exactly where to find their target species, that’s one of the reasons why commercial fishing is so effective. I’m sure you’ll agree with me that finding grey reef sharks on coral reefs (or at least where they haven’t been fished out) is not hard as the areas where they tend to aggregate are quite predictable. Any dive operator familiar with the species would be able to look at a nautical chart and identify areas on the reef where they would be likely to find the greys. As much as I would like that this knowledge escape fishermen, I’m afraid it doesn’t, and I don’t think that publishing information of residency and vertical movements of grey reef will make them massively more vulnerable. The reality is that by being site attached, these sharks are already vulnerable to local knowledge and populations can be easily affected by low levels fishing, commercial or artisanal. Now, it’s much harder to propose temporal and local closure to policy makers without good arguments. Showing that known natural aggregations of sharks are formed by a few resident individuals not hundreds of individuals in transit provide arguments against a common believe that the removal of sharks will be followed by migration of other individuals to the aggregations, which might help implementing fishing regulations in these sites. Also, knowing what sharks are doing in the water column might help promoting fishing regulations to try to minimize the capture of individuals when they are more vulnerable. Fishermen don’t need help to find sharks, that has been proven by the depletion of many populations in many places. However, police makers are unlikely to implement (or justify) fishing regulations without sound scientific research and that was the motivation for our study. Our research is done with conservation in mind but as DaShark said: “As always in science, the data can be used for good or bad purpose”, but not putting the information out there is basically not providing the tools the ones who can use it for a good purpose.
Regarding our study area, as you probably noticed reading the paper, we showed that the same grey reefs are highly resident to the aggregation (dive) sites, which means that localized (and cost effective) monitoring could help protecting at least part of the population. The sites monitored the sharks are among the most popular dive sites in Palau, where fishing is prohibited and dive boats and liveaboard boats are present during virtually all year around. I would say that if there are places relatively well monitored in Palau, those would be the places. I think that would make hard for commercial fishing vessels to go close to the reef, setting up a long-line and then leave unnoticed.

Gabe Vianna

Shark Diver said...

Yeah that's what you get for using Google Translate for Socrates...stupid Goggle;)

Shark Diver said...


Thanks for taking the time to post. From the outset let me make it abundantly clear I was not accusing your team of malfeasance and yes I am a fan and supporter of shark research.

More to the point I have spent a lot of time on long liners and yes there's an element of "hope for the best" once a line is set. That is after the following and other elements are taken into deep consideration:

1. Moon phase
2. Water depth
3. Water temp
4. Current
5. Salinity
6. Shift in variables(temp drops)

We knew the tuna, swordfish, and mako were in the region, but we did a lot of accounting before the set was dropped and any fresh data that came in was used, always.

Including tuna tracking data from researchers. Surprised?

My long line days are 20 years behind me and a career in conservation, strategy, and commercial shark diving replaced those days but I cannot help but wonder about a slew of shark research data that is available to anyone around the world.

Da Shark is correct "people use data for good and bad" but knowing that do we wash our hands of responsibility?

Could the bad be so damaging in certain cases as to mitigate any good?

As far as fisheries and government policy towards sharks, you and I diverge here.

I have zero faith that third world and second world governments use research data for anything but bad. Even here on the East Coast of the USA with our Cod fishery, data was ripped apart wholesale to push an entire species and 200 year old fishery to it's absolute breaking point. Smart people spent a lifetime doing Cod research and were ignored.

A lot of blogging that gets done here are trial balloons to much broader issues and examples are meant for discussion.

You brought some good points to this and having the discussion is healthy. This one hit a nerve around the research community.

By the looks of things this has not just been on my mind.

One thing we can never do is create a negative impression for shark research. It's hard enough to get funding and the little data that does come out can and sometimes does get used to great effect.

But the question about research data responsibility will remain and needs to be discussed.

I had my own "aha moment" at Isla Guadalupe, Mexico back in 2005.

The white shark site had just been discovered, we had enjoyed a few years of serious commercial shark site marketing in the form of tv shows, press releases, and even live radio broadcasts from the island.

Until we exposed this site these animals had been content to live here undisturbed for hundreds and perhaps thousands of years.

I had never imagined that our collective actions would attract trophy fishermen from the US and Mexico and yet...they did. Call it extreme ignorance but you can imagine my surprise in 2005 and again in 2006 when we had to literally chase three boats out of Pointe Norte. Two had actually hooked white sharks intent on killing them.

People use all kinds of information for good and bad, but having seen the bad, and having seen how fresh tuna tracking data made a 20% difference in catch ratios, I am concerned.

Thanks again for your comment.

Gabriel Vianna said...

No offence taken Patric, there is nothing wrong with a good discussion about science, as long as it's kept to a respectful and friendly level, of course. In fact I took the opportunity of your post to bring the subject to our research group and have had a couple of discussions about our responsibilities as scientists in regards to the information we make available.
Regarding your view about management and enforcement, I don't think our ideas diverge much. In my point view it's very important to provide the tools that will support responsible management but I agree that thinking that a model based solely on ecological arguments will work, this seems unlikely to be effective. That's why I believe that what you guys do as shark diving industry has an enormous potential and need to be better explore in terms of promoting conservation. But as you said, even that can be used for bad. However, in my point of view, if we don't do something and try the strategies we can to protect what is left thinking it can be used for bad we know exactly how bad the future will be.

Shark Diver said...

Something this well written needs to be seen twice. Hope you don;t mind.

"That's why I believe that what you guys do as shark diving industry has an enormous potential and need to be better explore in terms of promoting conservation. But as you said, even that can be used for bad. However, in my point of view, if we don't do something and try the strategies we can to protect what is left thinking it can be used for bad we know exactly how bad the future will be."

- Gabe