Sharks Matter, Here’s Why

A call comes in on the town’s hotline. A man reports having witnessed a shark attack a seal. The hotline was installed specifically for people to report shark sightings. It is a service installed in response to an attack that occurred back in the summer of 2020. A woman swimming near the shore in about 20 feet of water was killed by a great white shark. Hers was the first fatal shark attack recorded in Maine. Afterwards, other communities, some many miles away from where the attack occurred, began posting signs warning people to beware of sharks. Recently, buoys transmit real-time notifications have been installed that alert researchers and beach lifeguards that a radio tagged shark is in the area. The mood along coastal Maine ranges from nervousness to excitement at the possibility that sharks are present. Fear of sharks is palpably real for some people but as one environmental educator specializing in marine life has pointed out, of the 400 or so species of sharks only a few are known to attack humans.

Sharks matter for a healthy ocean

 Sharks are both loved and maligned creatures of the deep. For those who fear the toothy, cartilaginous fish, efforts to eliminate the sharks might be the best solution. These people may be unaware that sharks play an important role in maintaining a healthy marine ecosystem. Ellen Johnson writing for the Mystic Aquarium reminds readers that sharks have long been a member of the ocean community. They’ve lived on Earth for 450 million years, long before the dinosaurs existed, and survived four mass extinction events. As a top predator in marine ecosystems, sharks help limit the population size of other fish. In so doing, sharks maintain a balance in the undersea world. “The removal of sharks from coral reef ecosystems has been shown to trigger an increase of smaller predators that prey on herbivorous fish.” As an example Johnson writes that as “herbivore populations decline, and without enough herbivores grazing on algae, algae can quickly overgrow a coral reef. This shift from a coral-dominated reef to an algae-dominated reef reduces biodiversity and decreases the resilience of the reef to disturbances such as coral bleaching and storms.”

Sharks need our protection

Today, as the result of human interventions, many shark species face the threat of extinction. According to an article by John Cannon published on Mongabay.com, sharks are one of the most threatened groups of vertebrate animals. About a third of all know sharks species are considered threatened with extinction. Noted shark biologist and author David Shiffman says that the “biggest threat facing sharks and their relatives is unsustainable overfishing. There’s no doubt about that. A hundred percent of threatened species have overfishing as one of one or their only threat.” Put another way, one third of all living shark species are classed between Near Threatened and Critically Endangered (CR) by the IUCN Red List.

While some fisheries target sharks for their fins, a practice known as shark finning, an increasing number of sharks are fished for their meat. One reason is the growing demand worldwide for protein and, unlike bony fish, the shark skeleton is made from soft, flexible connective tissue known as cartilage. Cartilage is the same tissue that makes up the external part of the human ear.

Fishing, however, is not in itself threatening sharks with extinction. That happens when fishing practices are unsustainable, meaning more sharks are removed from the ocean then can be replaced by the birth of new individuals. A June 2020 article in iScience by Shiffman and colleagues states that while “unsustainable fishing of sharks is common historically and currently, there is no scientific doubt that sustainable shark fisheries can and do exist.” Shiffman and colleagues also differentiate between the specific practice of shark finning and fishing for sharks as a food fish. Policy solutions that focus solely on reducing sharks in the fin trade ignore the significant and growing mortality from a broader set of fishing practices.  

Jennifer Kennedy compiled a list of other practices that threaten sharks:  

* Shark biology —Some sharks take a long time to reach sexual maturity and reproduce. For example, male great white sharks don’t reach sexual maturity until they are at least 26 years old and females aren't ready to carry pups until they are 33 years old. Female sharks produce only a few pups per mating cycle. This translates into a population that takes a long time to recover from pressures that threaten them..

*  Bycatch—Sharks may unintentionally be caught in the nets of commercial fishermen seeking other fish. The sharks are bycatch because they weren’t the targeted species. Because sharks must keep moving in order to breathe, when trapped in a net the sharks may suffocate and die.

* Recreational fishing—Some species of sharks are sought after by recreational fishers. This can result in overfishing in some areas.  

*  Commercial Fishing—Shark species are harvested commercially for their meat, liver,  cartilage, jaws, and fins. Between 70 and 200 million sharks are killed annually by shark fishing.

* Coastal Development—Coastal areas are important to sharks. These are areas that sharks use for birthing their young. These areas also serve as valuable habitat for immature sharks and their prey. As humans build on coastal lands, the  health of the habitat is put in jeopardy, and thus affects sharks and other marine species.

*  Pollutants—Because sharks are at the top of food chains, when they eat tainted fish, the  pollution is compounded in their tissues. This process is called bioaccumulation.

* Shark nets—Shark nets are installed at some swimming beaches as a safety measure to keep sharks and swimmers separate. Unless quickly released, sharks that caught in these nets suffocate and die.

Sharks economics

Fishing for sharks has its economic benefits. When the practice becomes unsustainable, in other words overfishing occurs, the economic benefits are short term. Over time, the catch rate declines and profits eventually decline too. Sustainable fishing practices, result in long-term economic benefits and  shark populations are not placed in danger.

Johnson writes that in some areas sharks are worth “more alive than dead due to the growing popularity of shark ecotourism. While a single dead reef shark in Palau might sell for about $108, the same live reef shark could bring in nearly $2 million to the tourism industry in its lifetime.”

Economics can be used as an important tool in protecting sharks. Here are a few ways the World Wildlife Fund suggests you can use the power of your purse to help sharks.

* Avoid buying shark teeth, and other shark curios. While sharks are not typically caught just for their teeth, buying them may support unsustainable fisheries.

*Seek responsible dive tour operators when diving and snorkeling with sharks and rays. Ask if the operators use the Responsible Shark and Ray Tourism Guide.

*Avoid buying squalene health capsules and cosmetics that incorporate squalene as a moisturizer, as it may have come from sharks. Squalene can be derived from the oil rich livers of deep sea sharks.

*Avoid buying shark teeth and other curios made from sharks. Buying these things may directly or indirectly support unsustainable fisheries.