Here's why we need sharks. | Alastair Pollock Photography/Getty
It’s likely that the word shark makes you think of one of the countless horror films released since 1975’s classic thriller Jaws. But movies and fear mongering have given us a skewed impression of both the danger sharks pose and their importance to ecosystems, the ocean, and the planet in general.
Simply put: Sharks are essential. These dinosaurs of the sea have been around for 450 million years for a reason. The Earth—and all living things on it—need sharks to survive. And one of the best ways to protect them is to get to know them (like, really know them). Here is everything you need to know about sharks.
Sharks are so ancient that their earliest fossil records predate tree fossils by nearly 100 million years. Sharks are also one of the select few species (along with horseshoe crabs) to survive four out of five of Earth’s mass extinction events.
They are a keystone species, which means that they are essential for the optimal health of all other creatures within the same ecosystem. Many sharks are apex predators, but keystone species can also be herbivores such as the snowshoe hare, and trees like aspen and willow.
Keystone species are typically broken down into three different categories: ecosystem engineers (such as beavers), mutualists (such as bees), and predators (such as sharks), though some experts disagree on exactly where these distinctions begin and end.
Because of their importance, changing the population of a keystone species affects all other life within their ecosystem and beyond. For example, one study from 2013 found that declining tiger shark numbers off the north-western Australia coast caused an increase in mid-level predators.
This, in turn, reduced algae-eating fish populations and significantly impacted the health of the local reef systems. The deteriorating reef systems affected the species that live on the coral itself, and so on throughout the surrounding waters.
A separate study also found that losing an apex predator such as the shark can increase the impact of marine tropicalization, a climate-driven change in the underwater ecosystem. As both studies show, losing sharks is nothing short of catastrophic, even in what appears to be one localized area.
“When you take away the top predators, it actually leads to incredible modifications within the food chain,” Christine Figgener, Ph.D., a marine conservation biologist and the director of science and conservation for COASTS, told LIVEKINDLY.
“Top predators are usually there to regulate any species that they are feeding on,” continued Figgener. “If they are not able to regulate their prey species anymore, it can have really incredibly detrimental effects to the ecosystem.”
Figgener, who is currently working on sea turtle conservation research in Costa Rica, particularly highlighted the way that diminishing numbers of tiger sharks have caused the overpopulation of green turtles, in turn causing the overgrazing of seagrass—an extremely effective (and important) carbon sink.
Sharks also store carbon themselves. And while the majority of shark species live for between 20 and 30 years, the North Atlantic ocean’s Greenland Shark can live for a scarcely believable 300 to 500 years, all of which is spent sequestering carbon.
Tuna, swordfish, and sharks are all around 10 to 15 percent carbon, while large ocean mammals such as whales (who also fulfill the same role) can sequester an enormous 33 tons of CO2 throughout their lifetime.
When large fish species such as the above die naturally—typically sinking to the bottom of the ocean—their stored carbon is further sequestered there for thousands (perhaps millions) of years.
“It’s about when they die and all the carbon they have in their bodies, they take it to the ocean floor,” explained Figgener. “So it doesn’t go into the atmosphere. They get eaten up by bacteria and by sharks and by all of the other animals.”
Research shows that the hunting and fishing of marine animals interrupts this process, releasing part of the stored carbon into the atmosphere in the days following the fish’s capture and death.
Scientists estimate that 6.4 to 7.9 percent of the world’s sharks are killed every year, exacerbating climate change and environmental destruction in general. For context, 7.9 percent of the current global human population is more than 600 million people.
It has taken less than 50 years for humans to wipe out 70 percent of the world’s total shark and ray populations, two species that previously survived for hundreds of millions of years.
Sharks are hunted for their meat, organs, and unique skin, like many other animals. They have a rough epidermis and are covered in very small, teeth-like scales known as dermal denticles. These point towards the tail and reduce friction in the water, helping them move faster.
Shark’s fins provide balance, and the large, iconic, dorsal fin helps steer and stabilize them in the water. Each fin is like a fingerprint, and thanks to varied pigmentation, marks, and scars, some scientists working closely with sharks are able to identify individuals based on their dorsal fins alone.
Finning, the practice of removing the fins and discarding the rest of the animal (sometimes while still alive), usually for soup or medicine, is now restricted or illegal in many parts of the world. However, a lack of meaningful importation restrictions to support such a ban facilitates demand—similar to the ivory industry in the U.S. and fur farming in the UK.
In addition to the intentional hunting of sharks, overfishing, bycatch, pollution, and climate change are all also having a detrimental impact on the global shark population. “Industrial fishing is bad, I would say almost for any large vertebrate animal in the ocean,” said Figgener.
She also highlighted the general perception and treatment of sharks as an additional threat. For example, sharks are killed (both intentionally and unintentionally) along much of Australia’s coastline to protect bathers. And representation in the media has a direct impact on public perception of sharks and their unnecessary deaths.
Despite their longstanding and formidable reputation (thanks, Shark Week), the chances of getting hurt by a shark are astronomically low. In the U.S. alone, and excluding all but regular beach-goers, a person’s chance of getting killed by a shark is less than 1 in 264 million—significantly lower odds than getting struck by lightning.
Also, while sharks may not be a significant threat to humans, we are entirely responsible for their declining population. A 2013 study published in Science Direct estimated that around 100 million sharks are killed every single year, far exceeding any practical rebound rate. This must change, and soon, if we are to have any hope of mitigating climate change and preserving ocean wildlife.
Here are just some of the ways that you can support these important animals in your own life and beyond.
As noted above, the perception of sharks’ as ‘undesirable’ animals persists despite ongoing global education efforts.
One key way to help support sharks is to learn all you can about them and the issues they face today. Then, pass that knowledge on to other people in your community through discussions, the sharing of educational resources, and perhaps even hosting film screenings and movie nights.
Documentaries such as Mission Blue (2014), A Plastic Ocean (2016), and the recent Seaspiracy (2021) all touch on the threats facing ocean wildlife today, including sharks. Figgener specifically recommends the Sharkwater documentaries, released in 2006 and 2018, as powerful takes on the treatment of sharks.
“There’s also this really cool platform called Ocearch,” she added. “They study white sharks and have really cool footage and a really cool curriculum. They put a satellite transmitter on and you can pretty much follow those sharks live on the internet.”
“You can learn a lot about their migratory routes, their ecology, and I think that it’s an amazing tool to really lose your fear,” continued Figgener.
Writing a letter or email to your representative is a fantastic way to let them know that people care about protecting sharks and other marine animals. You could also write to congress regarding a more specific issue, such as shark finning, the prevention of ocean acidification, reducing overfishing in your area, or minimizing plastic waste.
Around the world there are several ongoing campaigns for additional marine reserves that need public support, including in the U.S. and the UK. Let your representative or MP know how you feel, and why you think additional environmental protection is important.
Open States offers a free service to look up your state legislators in the U.S., while the UK parliament website allows British residents to find their local MP. If you require additional support, third party site Write to Them facilitates contact with both local and national politicians in the UK.
Supporting conservation efforts in general also helps protect sharks. You can do this by donating time, resources, or money to organizations such as the Shark Research Institute, the IUCN Shark Specialist Group, the Shark Alliance, Coral Reef Alliance, Shark Stewards, Fin Fighters, Sea Shepherd, and many more.
Conservation groups and NGOs often appreciate volunteers, plus there are countless grassroots, community-led beach clean events worldwide you can get involved with. You could also “adopt” a shark, a service offered by 501 nonprofit Oceana, or do so for a friend as a sustainable gift.
“Always support organizations that are trying to educate and really provide conservation for sharks. MarViva, for example, is one that operates here in Central America,” said Figgener. “Misión Tiburón operates in Costa Rica, and Fins Attached is particularly against shark finning.”
Even if you avoid eating shark meat itself (which is sometimes sold under alternative names such as dogfish, flake, huss, lemon fish, and rock salmon) the fishing industry, in general, has a huge impact on marine life, the ocean environment, and by default, sharks.
Overfishing has already exhausted around 90 percent of the global fish population, and bycatch—the unintentional catching of other animals—impacts sharks and countless other species.
While some communities living in coastal areas depend on seafood and fish for survival, many of us can easily replace these foods with the increasing number of meat-free fish options available in stores and supermarkets. Swapping traditional seafood for plant-based options, where possible, helps to minimize your participation in industrial overfishing.
Around 10 percent of all produced plastic (around 270,000 tonnes and around 5.25 trillion individual pieces) ends up in the ocean. Microplastics, in particular, can be found in all manner of flora and fauna (including sharks), as well as food, air, and water.
Around 67 percent of sharks contain plastic and other man-made fibers. But cutting back on problematic unnecessary packaging also helps to reduce your carbon footprint and overall impact on the environment.
“Our addiction to plastics combined with the lack of mechanisms to protect our oceans is suffocating marine life,” says Will McCallum, the head of Oceans for Greenpeace UK. “Sharks sit on top of the marine food web and play a vital role in ocean ecosystems. Yet, they are completely exposed to pollutants and other human impactful activities.”
“We need to stop producing so much plastic and create a network of ocean sanctuaries to give wildlife space to recover. The ocean is not our dump, marine life deserves better than plastic,” he added.
This post was last modified on April 19, 2023 3:48 pm