by Roger Payne*

Roger's article attached highlights the issues of shark drum lines and nets and calls for the public to hold their politicians to the rule that "ignorance of natural laws is no excuse" with a small message to Tony Abbott. Finally, he outlines some of the alternatives on offer that are currently available.

 

Tiger Shark at Tiger Beach, Bahamas. 
Photo: Heinz ToperczerIn today’s world where shark populations are being overfished globally to the point of collapse, spending millions of dollars per year to kill sharks with drum lines and shark nets amounts to spending money on an almost baseless hope—the hope that it will reduce further the smallest cause of death for which data are kept. In doing this the government expends tax dollars that exceed what other groups receive, per-person-saved, and who work to reduce deaths from other causes that kill vastly more people.

It is clear that shark nets and drum lines are blind, non-discriminating techniques that kill endangered shark species as well as shark species that are headed that way fast. Apart from the illegality of killing endangered species, removing top predator species doesn’t solve a problem, it creates a problem—one that is bigger and vaster and that will eventually impact the lives of billions of humans and trillions of non-humans.

The problem I’m referring to stems from the fact that sharks are apex predators (i.e.: ‘top predator’ species that die from causes other than predation and are eaten by scavengers). What we now know is that the presence or absence of apex predators causes outsized influences on the entire ocean ecosystem of which they are a part. This happens via a process known as a ‘trophic cascade’ in which the effects of wiping out an apex predator cascade down through the entire food pyramid of which it is top predator. The effects can be catastrophic because the populations of smaller predators that the apex predator once kept in check can now explode and cause havoc to the predators that occupy the next lower step of the food pyramid. In this way the disruption works its way, i.e. cascades, all the way to the bottom of the food pyramid—its plant base.

Modern understanding of trophic cascades clearly shows that if we destroy populations of top predators we do so at our own peril. In fact, it would be hard to imagine a way to create a bigger disruption for a smaller investment.

From which follows the counterintuitive conclusion that no matter how far away you live from the ocean your life and the lives of your children and grandchildren depend on how healthy the ocean is. That is because the health of the ocean affects so many conditions that are critical to all life.

It may take years to feel the effects of having destroyed an apex species, but the consequences of having taken that step will eventually appear, whereupon the cost of reversing those consequences will have become vastly greater than what it cost to set them into motion. In fact, like global climate change, fixing such problems usually ends up being too expensive to afford—a process that is aided by the nearly-universal spinelessness of politicians.

Ignorance Is No Excuse:

In matters of law, ignorance is no excuse. Yet, because people fear sharks your government chooses to ignore scientific truth and to fund programs that kill apex predators, simply because it knows that doing so scores political points with the punters. Such a decision is purely sarcastic. The government has access to solid scientific advice from its own, world-class Australian scientists. In fact, it has paid them to spend their entire careers learning about the complexities of such problems. Yet the current Australian government is taking a cheap shot; funding an action that makes a show of “helping” in ways they know are not just ineffective but counter-productive. It’s an old political story;

“I want another term in office. I’m going for the votes. My grandkids can deal with the consequences. My platform will be: ‘What has the future ever done for you and me? Our generation should get to enjoy the benefits of what we do; the next generation can pay the costs; after all, we paid the costs of their upbringing—they got to where they are free.”

Shark caught on drum line in Queensland. 
Photo: Sea ShepherdOf course, by the time the grandkids are old enough to try to solve problems, solving them will have become too costly to afford. That means they’ll just have to learn to live with a quality of life that you and I wouldn’t tolerate.

“Homelessness isn’t all that bad, is it? Lots of people survive it just fine; they look healthy enough to me.”

That is an opinion that is formed by watching documentaries about homelessness on a wide-screen TV, while tilted back in a lounge chair, drink in hand.

The world (and that includes every Australian) needs to hold its politicians to a new rule: not just that ignorance of the law is no excuse but that ignorance of natural laws is no excuse.

I urge you to press your government to spend that portion of the funds they will otherwise spend on drumlines on Aussie scientists who yearn for enough support to develop new techniques that won’t trigger trophic cascades that disrupt the health of the seas, but will reduce interactions between humans and sharks.

Here is my message to Tony Abbott:

Dear Prime Minister Abbott, this situation gives you a wonderful opportunity to lead. The world will applaud you for solving a nasty problem, and what it costs your government will be lost in the noise level of whatever accounting system you use. And don’t worry, there isn’t an economic test sensitive enough to detect what solving the shark threat will have cost your national budget.

And Solutions?

Shark nets and drumlines aren’t the answer. Shark nets have been outmoded for at least 70 of the 80 years they have been around. Is the world to believe that in those 70 years there was no Australian able to come up with a better way to keep sharks out of near shore waters where people swim? I’m confident that there are Australians who have aspirations to do such research and would be grateful even for modest funding to test their ideas.

One of the more promising techniques that you Aussies have already started to investigate is the use of bubble curtains made by forcing compressed air through lengths of perforated hose that are lying on the sea floor. Tests already show sharks avoiding bubbles from divers and such perforated-hose air sources, but it needs more funding for more comprehensive tests.

The main worry is that if bubbles are produced constantly the sharks may become habituated enough to no longer fear bubbles. How about finding out? Sharks could be motivated to dare to cross air curtains by baits on the other side. It has already been started. But how about more funding for such tests?

It might also be worthwhile to try developing a sonar that could sound a warning when a shark large enough to pose a problem approaches. Such a system would make it necessary only to deliver air to a specific length of hose when a large shark was detected—a protocol that would both save on the costs of compressing air and keep the presence of air bubbles novel to sharks, which might keep them un-inclined to approach air curtains.

Furthermore the appearance of masses of surface bubbles could alert lifeguards on beaches to the presence of large animals in their area. Such approaches might prove useful. Surely it’s worth trying out some innovative techniques rather than just continuing to kill endangered sharks when there is no solid evidence that it actually reduces the probability of shark attacks.

 

Roger Payne presenting at the Sea Shepherd summit. Photo: Eliza Muirhead

*Roger Searle Payne has written the following article on killing endangered sharks. Roger is a biologist and environmentalist, famous for the 1967 discovery (with Scott McVay) of whale song among humpback whales, and later became an important figure in the worldwide campaign to end commercial whaling. Roger has received a United Nations Environment Programme Global 500 Award (1988) and a MacArthur genius award (1984) among other awards for his research. He is a knight in the Netherlands Order of the Golden Ark (1977) and was a co-recipient of the Albert Schweitzer medal, Animal Welfare Institue (1980). The Humane Society of the U.S. presented Roger the Joseph Wood Krutch Medal in 1989 and the Lyndhurst Foundation conferred its Lyndhurst Prize on him in 1984. Most recently, he received Honorary Membership of the Society for Marine Mammalogy (2010).

Roger's article attached highlights the issues of shark drum lines and nets and calls for the public to hold their politicians to the rule that "ignorance of natural laws is no excuse" with a small message to Tony Abbott. Finally, he outlines some of the alternatives on offer that are currently available.