“Fish are friends, not food.” – Bruce from Finding Nemo. When I watched Disney’s Finding Nemo (2003) as a child, I was absolutely horrified by Bruce the Great White Shark. I was so afraid that when I went on family vacations to the beach, I would be wary of sharks patrolling. I would watch out for the triangular fin and didn’t want to stray too far away from the shore. Ironically, I’ve never seen the iconic Jaws (1975) movie. The director, Steven Spielberg, has said he “truly regrets” his portrayal of great white sharks and the movie’s contribution to the animal’s population decline. Even the author of the 1974 book Jaws, which inspired Spielberg’s movie, Peter Benchley, has apologized for the impact his book had on sharks and dedicated the rest of his life to shark conservation! Check out Benchley’s website–it’s awesome!

I’m not sure when I became a big fan of sharks, but I think it might’ve been because I watched a YouTube or TikTok video about them, and since then, I love sharks!

Background

Sharks belong to the class Chondrichthyes, or cartilaginous fish, meaning their skeletons are made of cartilage, rather than bone like other fish (Chapman, 2017). Fossil records have shown that members of this class have been around since 400-450 million years ago, which also means that sharks are older than trees and some dinosaurs (Chapman, 2017)! Chondrichthyans represent “one of the most species-rich lineages of predators on Earth and they continue to play important functional roles in coastal and oceanic ecosystem structure and function” (Chapman, 2017). The Chondrichthyes class has two groups: Holocephali and Elasmobranchii (“Shark Species”). The Elasmobranchii group has 8 orders of sharks, so each order classifies the “biology, physical characteristics, and behavior of sharks in that order” (“Shark Species”). Check out the Shark Research Institute’s website to learn more about sharks from different orders (you can also click on a shark to learn more about them). 

Sharks are typically found in marine habitats (although bull sharks, Carcharhinus leucas, may be found in estuaries and rivers in tropical/warm temperate regions), from shallow coastal waters and the continental shelf and slope to the deep ocean (Bennet, 2005). Sharks are highly diverse, with species ranging in size from about 20cm to over 18m (Dedman et al., 2024).

Here are some fun facts! Whale sharks are the largest fish in the sea—they can grow more than 12m long and can weigh over 21 tonnes (Chapman, 2017). You can visit Yushan, the whale shark, at the Georgia Aquarium (the only US aquarium with a whale shark). I visited the aquarium two summers ago, and whale sharks are really just gentle giants. Greenland sharks are the “longest-lived vertebrate known, with recent studies estimating a lifespan of about 390 years, give or take 120 years” (Nielson et al. 2016). Isn’t it crazy to think a species of shark could outlive three human family generations? 

Ecological Roles of Sharks

It’s actually a misconception that all sharks are apex predators (Chapman, 2017). Their exact role in the ecosystem depends on the “species, region, age/size, behavior, and/or sex” (Chapman, 2017). Chapman explains that apex predators must occupy the highest trophic level, control the ecosystem from the top down, and influence the productivity of the entire system (2015). In addition, “macropredatory and large mesopredatory sharks often induce behavioral shifts in their potential prey through predation risk and possibly competitive interactions with other predators” (Dedman et al., 2024). This means that sharks can impact how prey feed, hide, or move. Most sharks do not uphold these behaviors and would be classified as mesopredators (mid-level predators); only a select few sharks are considered apex predators, i.e., “great sharks” (Chapman, 2017). Sharks are not simply large predators: they can fill ecological roles at varying trophic levels (Dedman et al., 2024). Their diets range from filter feeding (like whale sharks) to parasites to small crustaceans to classic big predators that eat fish, turtles, seals, and other sharks (Dedman et al., 2024). However, it is challenging to create a comprehensive “understanding of ecological roles and the importance of sharks because of the inherent difficulties of studying their interactions and the mechanisms through which sharks may–or may not–affect ecosystems” (Dedman et al., 2024).

Sharks also have a bottom-up and/or facilitation role in ecosystems. Though research here is currently limited, we know that sharks move nutrients across great distances: “from pelagic environments to coral reefs, shallow to deep mesophotic coral reefs and vice versa, coastal oceans to estuarine waters, and across latitudinal gradients” (Dedman et al., 2024). These nutrients are deposited via “egestion and excretion or carcasses of sharks that die” (Dedman et al., 2024). It is worth noting that the ecological importance of this deposition needs to be further studied, as it remains unknown. 

Threats to Sharks

According to Dulvy et al.,”24% of shark, skate, and ray species are considered Threatened with extinction by the IUCN Red List’s Shark Specialist Group (2014). Targeted overfishing and bycatch (unintentional catches) contribute to the shark population decline (Shiffman and Hammerschlag, 2016). Shark fishing involves the sale of meat (for consumption), jaws (as tourist trinkets), cartilage and liver oil (as alternative medicine); the major reason for shark fishing is for shark fin soup (Shiffman and Hammerschlag, 2016). According to the Fisheries and Aquaculture Department (FAO), trade in shark parts is worth approximately US $1 billion annually worldwide (2010). Unfortunately, because of sharks’ slow growth, late maturity, and low reproductive rate, sharks are especially vulnerable to overfishing (Friedrich et al., 2014).

Conservation Efforts 

Raising awareness about shark issues and the destructive impacts human activities have on shark populations has been found to improve attitudes towards shark conservation (Friedrich et al., 2014). At a consumer level, we can consider purchasing sustainably sourced seafood or engage with campaigning for policy change (Friedrich et al., 2014). The image of sharks as fearsome predators greatly limits public engagement and support for shark conservation, which is due to cultural representations in media, such as Jaws and sensationalized media reports of shark attacks (Friedrich et al., 2014). Effective shark protection is rooted in “international strategy, changes to fisheries regulations, and tailored conservation tools (Friedrich et al., 2014). To determine effective conservation strategies, we must study ecological communities, species’ roles, and “the context of pervasive human presence in the oceans” (Dedman et al., 2024). 

Video of Yushan and Taroko from 2024 that I took! Unfortunately, Taroko died in August 2025.

Whale Sharks – Yushan and Taroko at the Georgia Aquarium’s Ocean Voyager

Sources:

Chapman, B. (2017). Shark attacks: Myths, misunderstandings and human fear. Csiro Publishing.

Bennett, M. (2005). The role of sharks in the ecosystem. St. Lucia: School of Biomedical Sciences, The University Of Queensland.

Dedman, S., Moxley, J. H., Papastamatiou, Y. P., Braccini, M., Caselle, J. E., Chapman, D. D., Cinner, J. E., Dillon, E. M., Dulvy, N. K., Dunn, R. E., Espinoza, M., Harborne, A. R., Harvey, E. S., Heupel, M. R., Huveneers, C., Graham, N. A., Ketchum, J. T., Klinard, N. V., Kock, A. A., … Heithaus, M. R. (2024). Ecological roles and importance of sharks in the Anthropocene Ocean. Science, 385(6708). https://doi.org/10.1126/science.adl2362

Dulvy, N.K., Fowler, S.L., Musick, J.A., Cavanaugh, R.D., Kyne, P.M., Harrison, L.R., Carlson, J.K., Davidson, L.N.K., Fordham, S.V., Francis, M.P., Pollock, C.M., Simpfendorfer, C.A., Burgess, G.H., Carpenter, K.E., Compagno, L.J.V., Ebert, D.A., Gibson, C., Heupel, M.R., Livingstone, S.R., Sanciangco, J.C., Stevens, J.D., Valenti, S. & White, W.T. (2014). Extinction Risk and Conservation of the world’s sharks and rays. eLife 3. (Online DOI: doi: 10.7554/eLife.00590).

FAO Fisheries and Aquaculture Department (2010). The state of world fisheries and aquaculture. Rome: Food and agriculture organization of the United States.

Friedrich, L. A., Jefferson, R., & Glegg, G. (2014). Public perceptions of sharks: Gathering support for shark conservation. Marine Policy, 47, 1–7. https://doi.org/10.1016/j.marpol.2014.02.003

Shiffman, D. S., & Hammerschlag, N. (2016). Shark conservation and management policy: A review and Primer for non‐specialists. Animal Conservation, 19(5), 401–412. https://doi.org/10.1111/acv.12265