Riley Elliott: Why sharks matter

If you follow anything to do with the ocean, you should have realised that sharks are facing major issues.

Sharkman

The most common is their battle against the Jaws-driven, media-induced fear factor but, more recently, their over-exploitation because of shark finning.

Peoples’ general perception of sharks means that care or want for conservation is not commonplace — but when they are provided with science explaining why sharks matter, their perceptions often change rapidly.

Sharks have existed for over 450 million years, since well before dinosaurs. They are of the longest existing vertebrate lineage in history, one that has evolved a critical role in the marine ecosystem — the apex predator. Top-down predator pressure not only picks off the weak and sick but it has also forced animals to evolve camouflage, schooling behavior and predator evasion tactics. Sharks stabilise the marine environment and, in doing so, ensure that all its inhabitants exist in a balance crafted over millions of years. A large part of the oxygen we breathe comes from the ocean; its continual production relies on a healthy ecosystem — one that requires sharks.

In the last 20 years, however, sharks have been over-exploited for their fins, resulting in up to 90 percent of the world’s sharks being wiped out. One in five shark species are now threatened with extinction. 

Sharks have always been a major by-catch in tuna surface long-line fishing, with more sharks commonly caught than the targeted tuna. Historically sharks were worthless and were cut free. However China’s free trade and open markets during the 1990s resulted in an exponential increase in GDP, and thus accessibility to the expensive, status symbol dish that is shark fin soup. To provide for this demand, 70,240 million sharks were finned each year globally.

In the absence of historic catch data, stock size estimates have been and continue to be near impossible for most shark species, especially the highly migratory ones that make up the majority of by-catch. The blue shark is the most commonly caught and finned species in this trade — over 80,000 a year were finned in NZ waters — yes that’s right, New Zealand waters. We were one of the top ten exporters of shark fins! Yet stock assessments and impact of current catch on population sustainability are listed as “unknown” by our Ministry for Primary Industries. 

The impacts of large-scale removal of these apex predators has been well documented around the world, from entire shell fish industries collapsing to coral reef ecosystems breaking down. In New Zealand we earn NZ$1.65 billion a year from the marine ecosystem — so why, in the light of these trophic cascades, would we blindly fish these apex predators?

In my opinion it’s a trifecta — shark science is juvenile, only recently revealing even basic biology and behavior, especially for offshore species; government policy seems to start with economics first when it comes to environmental resource exploitation, with science trying to play catch up to prove whether decisions are adverse; and people are scared of sharks and thus do not mind their demise.
For the past five years I have used media, publication and stimulating imagery to increase the public uptake of science in order to change peoples’ perspective of sharks and thus allow for their conservation.

“People only protect what they love; they only love what they understand; and they only understand what they are taught” — Baba Dioum.

Over the past two years, in conjunction with Leigh Marine Laboratory and Professor John Montgomery, my PhD project has satellite-tagged 18 blue sharks, producing what will become the world’s most in-depth understanding of this highly migratory species. The extent of migrations, breeding and pupping grounds, trophic role and catchability are being defined. The communication of this science to the New Zealand public and increased knowledge of the issue around shark-finning contributed to the recent success of getting shark-finning banned in New Zealand waters as of October 2014.

A recipe that has become clear to me in addressing conservation issues is that public opinion counts and, if backed by science, it can be a very powerful tool in achieving necessary environmental protection. Just recently this approach proved successful again, in one of the major human-animal conflicts — the Western Australia shark cull — ruled as adverse to the environment largely due to mass public opinion backed by science.

I continue my PhD project, coupled with public communication, most recently through my book, published by Random House, and TV series Shark Man.

Shark man video

Riley is studying for his PhD in Marine Science at the University of Auckland.