Sharks might seem mysterious, but that's because they are hiding a secret identity - they are Ocean Superheroes. For 450 million years, sharks have kept the oceans thriving and healthy. During this time, other organisms from seagrass to snails, have adapted to thrive in an ecosystem that includes sharks.
(Cover image photo by Alessandro de Maddalena)
However, because of their undeserved bad reputation, people seem to turn a blind eye to the hundreds of millions of sharks that are killed by humans every year. it doesn't matter whether you're a shark lover or a shark hater, you are almost certainly dependent on a healthy biosphere and economy - and sharks are hugely important in protecting it. Let's find out how.
Sharks regulate the ecosystem
As predators often at, or near the top of the food web, sharks are crucial to maintaining the balance between their own prey species, and the resources that their prey use.
Sharks allow smaller species to recover - Sharks control the abundance and distribution of mesopredators (smaller predators that fall somewhere in the middle of the food chain). With sharks controlling the numbers of the mesopredators, many smaller species are given the ability to survive in ecosystems where sharks are present, rather than being over-exploited by the smaller predators, that would otherwise flourish rapidly in the absence of sharks.
Sharks protect kelp forests, seagrass beds, and coral reefs - Where grazing species are present in large numbers, sharks show up! This affects the habitat of these grazers and forces them to spread out more - helping corals, plants, and algae by spreading out the burden of being consumed, instead of creating local depletion. The presence of sharks and other predators helps prevent trophic cascades, where the removal of one species collapses the entire food chain. Everything is connected eg. - in the absence of sharks, a predatory grouper can thrive. The grouper's small herbivorous prey starts to decline due to over-exploitation by the grouper. This decline causes the algae to flourish which in turn kills off corals... and the cascade continues.
Sharks help their prey stay healthy - Predators like sharks always aim to be as efficient as possible. This means that when a shark catches prey, they usually end up catching animals that are slower, less aware of their surroundings, or less effective at camouflage than the rest of their species. This has the benefit of removing sick animals, like those prone to parasite infections, or those with poor genetic traits, like more easily visible colours, and thus improves the health of the prey species population.
Sharks provide money, jobs, and security
Sharks are good for fisheries - By maintaining healthy habitats, sharks prevent the collapse of ecosystems. When sharks have been removed, fishing industries that depend on animals lower in the food chain have collapsed, resulting in economic impacts, job losses, and even affecting traditional practices. For example, in the early 2000s, a century-long scallop fishery in North Carolina was brought to a permanent end, as a result of the overfishing of sharks. The 11 largest local shark species were fished to depletion over a period of 35 years, and as a result, the small rays that these sharks would have regulated thrived and ate all the scallops in a trophic cascade.
Sharks promote tourism - Scuba diving, shark cage diving, eco-tours, and more - sharks and the diverse ecosystems they help facilitate can create significant employment opportunities for coastal communities in the form of tourism and recreational activities. Studies in the Bahamas have shown that individual sharks can be worth millions of US dollars in their lifetimes and tourism contributors, and unlike fishing, which has only a small albeit easy reward, sharks as boons to ecotourism have the prospect of creating stable income streams.
Sharks are part of healthy ecosystems, but they aren't alone and we need to protect our marine species, especially when food webs are complex and poorly understood. What is understood, are the economic benefits of biodiversity - and sharks are integral to maintaining that.