Why care about sharks?

The word “shark” can strike fear into the hearts of many people. Our primal terror of large predators means we often associate these animals with threat or horror. But in reality, there are very few species of sharks which actually pose a threat to human beings and even these ‘dangerous’ animals are critical for the health of our planet. So why are sharks so threatened? Why would this ever affect your life? In short, why should you care about sharks?

Sharks are seriously overfished, which has lead to massive population declines (Image Credit: Anastasios71 / Shutterstock)

We are now more aware than ever that our environment is threatened by human activity; climate change, plastic pollution, ocean acidification; we hear these terms in the news and on social media regularly. So, with the looming threat of melting polar icecaps, global desertification and extreme weather events, you might ask yourself why the plight of sharks should be a priority?

You should care, for many reasons... Let’s see if we can find one that applies to you:

Sharks are Critical for the Health of Ocean Ecosystems

Sharks are predators, meaning they gain their nutrition by eating other animals. Some sharks are “mesopredators” (middle predators), some are “apex predators” (at the top of the food chain), but either way they exert “top-down” control of the ecosystem (Roff et al, 2016).

A simple food chain with a shark as apex predator (Roff et al, 2016)

You might not think the shark at the top has anything to do with the plants at the bottom, but every species within a community is interconnected with every other in a delicately balanced web of interactions. The removal of sharks not only affects other species in their food web but also affect the dynamics of the entire community; shifting nutrient cycling and even altering the physical environment. This is known as a "trophic cascade" (Roff et al, 2016).

As an example, imagine an apex predator shark is removed from a community. The animals they normally eat (the mesopredators) are released from predation pressure and so their population sizes explode... More of these animals hunting means the populations of their prey then decrease... If these animals are herbivores, with fewer animals come less grazing on plant life... Plant growth booms, potentially even causing algal blooms, that can smother entire coral reefs! To keep our marine ecosystems healthy it is critical that healthy populations of every different type of species is maintained, including sharks (Roff et al, 2016, Ferretti et al, 2010).

As they create top-down control of the ecosystem, sharks are vital to the health of marine habitats like coral reefs (Image Credit: frantisekhojdysz / Shutterstock)

Sharks are Important for Our Leisure Activities

Many people use the ocean environment for fun during their free time. For example, some people enjoy a spot of fishing. Some fish for relaxation; enjoying time out in the fresh air and enjoying nature, others fish for sport in competitions. Many people also enjoy scuba diving or snorkelling to see corals, fish and (maybe) sharks, either on a regular basis or as an exciting treat during a tropical holiday (Cisneros-Montemayor et al, 2013).

If shark populations collapsed, these activities would no longer be on the schedule for the weekend or on your next holiday. I know that is something I would certainly miss.

Whale shark snorkelling trips are vital for the economy in the Philippines (Image Credit: Tatiana Nurieva / Shutterstock)

Sharks are Important for The Global Economy

Shark ecotourism is a massive industry all over the world and is only continuing to grow every year. Whether it's going out on a glass bottomed boat, snorkelling, SCUBA diving or cage diving, this booming industry is absolutely critical to the economy of many nations. Shark tourism creates both local and national capitol, and provides jobs for millions of people all over the world. This is not just limited to tropical climes, shark tourism is important to the economies of many western nations, like the UK (Cisneros-Montemayor et al, 2013).

It is not just ticket sales with the company itself that shark tourism has an impact on, but there are many jobs in the local community that are created surrounding tourism spots; hotels, restaurants, local shops. If ocean ecosystems are permanently damaged and these industries collapse, it could have a huge affect on individuals and communities around the globe (Cisneros-Montemayor et al, 2013).

Many people rely on shark meat or other fish as a protein source in their diets, so healthy stocks are critical to their communities (Image Credit: Toto Santiko Budi / Shutterstock)

Sharks Ensure Ample SeaFood Stocks

Some people (sadly) are not interested in environmental concerns, as these issues seem to be detached from their lives and, therefore, irrelevant. However, the survival of sharks may be more relevant to your daily life than you ever realised. As we have already discussed, top-down control can be critical in maintaining healthy populations of lots of different species... Many of these species are, in fact, our seafoods. If shark declines lead to a trophic cascade, we could very well see the collapse of fish stocks not far behind.

Shark declines could lead to collapses of commercially important fish stocks, affecting economies and threatening coastal communities with famine (Image Source: Roff et al, 2016)

If fisheries did collapse and were forced to close, not only may you not be able to enjoy certain seafoods anymore, but this could have an enormous impact upon countries which rely upon seafood at a substance level. Many communities of the coastal countries in Africa and Asia rely on fishing for their food and the Food and Agriculture Organisation (FAO) estimates that an excess of 1 billion people globally rely on seafood as their major source of protein. If we do not manage shark populations successfully, it is very possible we could see localised famines in the future (FAO, 2000).

Overfishing is the greatest driver of shark declines around the world (Image Credit: Andreas Altenburger / Shutterstock)

Ethics

Human beings as a species are consumerist; we exploit natural resources and engineer our environment for our own comfort and prosperity, but it could be argued that we are animals just like any other and we have no more right to this world than any other species. Don't sharks have just as much of a right to life as us!?

Sharks are some of the most threatened animals on the planet today, with as many as a quarter of all species at risk of extinction. It is our overfishing, our destruction of ocean habitats, our reckless overexploittaion of natural resources that has lead to these terrible declines... so don't we ethically have a responibity to try to fix it? I for one believe that we do.

If you want to learn more, you can read The Significance of Sharks and Threats to the Fin.

References

Cisneros-Montemayor, A., Barnes-Mauthe, M., Al-Abdulrazzak, D., Navarro-Holm, E. and Sumaila, U. (2013). Global economic value of shark ecotourism: implications for conservation. Oryx, 47:03, 381-388. Access online.

FAO (2000). The State of World Fisheries and Aquaculture. FAO, Rome, Italy. Access online.

Ferretti F., Worm B., Britten G.L., Heithaus M.R & Lotze H.K. (2010). Patterns and ecosystem consequences of shark declines in the ocean. Ecology Letters, 13, 1055-1071, doi: 10.1111/j.1461-0248.2010.01489.x. Access online.

Roff G, Doropoulos C, Rogers A, Bozec Y-M, Krueck NC, Aurellado E, Priest M, Birrell C & Mumby1 PJ (2016). The ecological role of sharks on coral reefs. Trends in Ecology and Evolution, 31:5, 395-589. Access online.

By Sophie A. Maycock for SharkSpeak