A scientific mission to save the sharks

This article was initially featured on Knowable Magazine.

A hammerhead shark lower than one meter lengthy swims frantically in a plastic container aboard a ship in the Sanquianga National Natural Park, off Colombia’s Pacific coast. It is a fragile feminine Sphyrna corona, the world’s smallest hammerhead species, and goes by the native title cornuda amarilla — yellow hammerhead — due to the colour of its fins and the edges of its splendid curved head, which is stuffed with sensors to understand the motion of its prey.

Marine biologist Diego Cardeñosa of Florida International University, together with native fishermen, has simply captured the shark and implanted it with an acoustic marker earlier than shortly returning it to the murky waters. A collection of receivers will assist to observe its actions for a 12 months, to map the coordinates of its habitat — precious info for its safety.

That hammerhead is way from the solely shark species that retains the Colombian biologist busy. Cardeñosa’s mission is to construct scientific information to assist shark conservation, both by finding the areas the place the creatures stay or by figuring out, with genetic checks, the species which are traded in the world’s most important shark markets.

Sharks are underneath menace for a number of causes. The demand for his or her fins to provide the primarily Asian market (see field) is a really profitable enterprise: Between 2012 and 2019, it generated $1.5 billion. This, plus their inclusion in bycatch — fish caught unintentionally in the fishing business — in addition to the rising marketplace for shark meat, leads to the dying of thousands and thousands yearly. In 2019 alone the estimated whole killed was a minimum of 80 million sharks, 25 million of which have been endangered species. In truth, in the Hong Kong market alone, a serious buying and selling spot for shark fins, two-thirds of the shark species offered there are liable to extinction, in accordance to a 2022 research led by Cardeñosa and molecular ecologist Demian Chapman, director of the shark and ray conservation program at Mote Marine Laboratory in Sarasota, Florida.

Sharks proceed to face a sophisticated future regardless of many years of laws designed to shield them. In 2000, the US Congress handed the Shark Finning Prohibition Act, and in 2011 the Shark Conservation Act. These legal guidelines require that sharks introduced ashore by fishermen have all their fins naturally connected and goal to finish the observe of stripping the creatures of their fins and returning them, mutilated, to the water to die on the seafloor. Ninety-four different international locations have carried out related rules.

Perhaps the most important political and diplomatic instrument for shark conservation is in the arms of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), composed of 183 member international locations plus the European Union. The treaty provides three levels of safety, or appendices, to greater than 40,000 species of animals and vegetation, imposing prohibitions and restrictions on their commerce in accordance to their menace standing.

Sharks have been included in CITES Appendix II — which incorporates species that aren’t endangered however may turn out to be so if commerce is just not managed — in February 2003, with the addition of two species: the basking shark (Cetorhinus maximus) and the whale shark (Rhincodon typus). Following that, the listing of protected species grew to 12 after which elevated considerably in November 2023 with the inclusion of 60 extra species of sharks in CITES Appendix II.

But do these instruments truly shield sharks? To hunt down solutions, over the previous decade researchers have labored to develop checks that may simply determine which species of sharks are being traded — and decide whether or not protected species proceed to be exploited. They have additionally centered on finding out shark populations round the world so as to present info for the institution of protected areas that may assist safeguard these animals.

Which shark does that fin belong to?

The port of Hong Kong, together with the Chinese metropolis of Guangzhou, is certainly one of the world’s main facilities for the commerce in shark fins, thought-about by many Chinese communities to be a delicacy, usually served in soup. Hong Kong serves as a authorized importer, re-exporter and client of those cartilages, each recent and packaged in baggage of trimmings. A decade in the past, Cardeñosa, Chapman and different members of their staff started an investigation there, with the objective of answering a query: Are protected shark species being exploited?

Many fins look the identical, making it troublesome to know whether or not they belong to CITES Appendix II-listed sharks. But the scientists have been assured that, with the use of genetic evaluation instruments, their query may very well be answered.

After scouring a market that stretches for a number of blocks of storefronts cluttered with baggage and jars of yellowed shark fin clippings, Cardeñosa returned to his lab in Florida with a number of randomly chosen bundles. The problem, then, was to develop the evaluation for molecular identification in the useless materials. “The problem is that processed fins have degraded DNA, preventing their identification with established protocols,” Cardeñosa explains. “Genetic approaches to identify shark products exist, but they typically rely on sequencing large regions of DNA, which can fail when working with highly processed products.”

So Cardeñosa, Chapman and different colleagues developed a brand new take a look at, utilizing a way referred to as DNA barcoding, that reads quick items of DNA sequences to detect what species of shark is in a pattern. It works not solely on fin items but additionally on cooked shark fin soup and beauty merchandise fabricated from shark liver oil.

DNA barcoding expertise makes use of small segments of the cytochrome c oxidase I gene, COI, as molecular tags. Each animal species has its personal label or barcode of these DNA segments, and forensic geneticists evaluate the DNA sequences of the pattern with a database of genomic sequences from dwelling animals.

The technique designed by Cardeñosa and colleagues is simpler than the authentic barcoding expertise as a result of, as a substitute of getting to use all 650 DNA base pairs of the COI  gene to function a species barcode, the take a look at can determine a species with simply 150 base pairs — in impact, a mini-barcode. The take a look at additionally concurrently analyzes a number of mini-barcodes or the COI  gene for every species, as a substitute of only one. This makes it simpler to determine the species in extremely processed merchandise, even in a bowl of soup.

During 4 years of utilizing that protocol on 9,200 fin clippings bought in Hong Kong, Cardeñosa and colleagues confirmed that the species most traded for his or her fins included sharks listed on CITES Appendix II — particularly, a number of species of the household Sphyrnidae, which incorporates hammerhead sharks, in addition to the blue shark (Prionace glauca).

To make it less complicated to determine shark species being traded, Cardeñosa and Chapman determined to convey the lab to port. In 2018, they printed in Nature  the design of a transportable lab for fast, on-site DNA evaluation: In a single response that takes lower than 4 hours, it might detect 9 of the 12 shark species that have been listed on CITES Appendix II at the moment. “It’s a PCR or polymerase chain reaction test, just like a Covid test,” Chapman explains, however as a substitute of detecting fragments of viral genetic materials, it detects fragments of the COI  gene, that are totally different in DNA sequence for every of the 9 shark species. It is straightforward to use, and subsequently appropriate for port officers, and prices 94 cents per pattern, making it inexpensive even for low-income international locations.

Now that there are greater than 70 species of sharks underneath CITES safety, extra highly effective instruments will probably be wanted to determine protected species amongst the supplies being traded. Chapman is working with the firm Ecologenix, which has developed a modification to the PCR take a look at that permits it to determine many species directly.

Ecologenix’s improvement relies on a expertise known as FastFish-ID, which was created to determine bony fish. A small-scale research in Indonesia confirmed that the expertise will be tailored to be used in cartilaginous fish like sharks. The identification approach additionally makes use of the COI  gene however incorporates fluorescent dyes and machine studying into the PCR process to assist acknowledge species. Although it’s dearer — at $10 per take a look at — it’s extra highly effective as a result of it might determine many extra species directly.

Protecting sharks’ houses

Genetic evaluation not solely permits scientists to know what sort of shark the fin or meat being traded belongs to, it might additionally inform them the place the animal comes from geographically. Hammerheads are particularly suited to these research, not solely as a result of the DNA database that exists on them is so intensive, but additionally as a result of they have an inclination to return to breed in the place the place they have been born.

In 2009, Mahmood Shivji, director of the Save Our Seas Foundation at Nova Southeastern University in Fort Lauderdale, Florida, co-led with Chapman a research that demonstrated that the use of a forensic technique known as genetic inventory identification, or GSI, may very well be used to decide the provenance of fins traded in the Hong Kong market.

The researchers used GSI to look at the DNA in fins from 62 hammerhead sharks (Sphyrna lewini) obtained from the market. GSI appears to be like at DNA contained in the mitochondria, an organelle of the cell that’s transmitted by the mom and is subsequently traceable to the creature’s regional birthplace. The research discovered that the sharks got here from the Indo-Pacific, Eastern Atlantic and Western Atlantic basins, and that absolutely 21 p.c of them got here from the Western Atlantic the place they’re listed as a species liable to extinction. In different phrases, the worldwide commerce in shark fins continues to threaten endangered populations on this area.

A subsequent research in 2020 by Chapman and colleagues revealed that 75 p.c of hammerhead shark fin clippings present in Hong Kong markets got here from two populations originating in the Pacific Ocean, however largely from the Eastern Pacific — 61.4 p.c of all clippings — the place this species is listed as endangered underneath the US Endangered Species Act.

Identifying which shark species are being traded and monitoring their geographic origin is just a part of the conservation effort. Knowing the actions and inhabitants construction of various shark species can also be necessary in figuring out which marine areas ought to be underneath safety.

“Sharks are quite large, by marine fish standards, and have the ability to make long-range movements. The perception that they tend to be highly mobile has led many nations to wait for international management policies,” Chapman and coauthors wrote in an article in the Annual Review of Marine Science. But in actual fact, some populations of sharks would profit from protecting laws at smaller scales, the authors say.

After analyzing the outcomes of over 80 research on shark monitoring and inhabitants genetics, the scientists recognized a minimum of 31 shark species that present coastal behaviors, both by exhibiting residency (remaining in an outlined geographic space for an prolonged interval), constancy (returning after lengthy absences) or philopatry (returning to their birthplaces to reproduce). These shark populations would in all probability reply nicely to successfully designed protected areas and protecting laws at the nationwide degree, the authors conclude.

Monitoring such coastal sharks, together with these dwelling amongst coral reefs, is subsequently key, Cardeñosa says — therefore the significance of the Global FinPrint mission, of which Chapman is scientific director. It is the largest world survey of sharks that inhabit the coral reefs, achieved by attaching cameras to underwater constructions and deploying bait to appeal to sharks. The first part of the mission, which led to 2018, was carried out in 58 international locations and greater than 400 reefs, evaluating protected and unprotected marine areas.

During that first part of Global FinPrint, Cardeñosa was in control of monitoring the UNESCO Seaflower Biosphere Reserve, an enormous oceanic archipelago in the Colombian Caribbean. The outcomes have been surprising. Even although the corals in massive components of Seaflower are usually not doing nicely, the mission discovered a excessive abundance of sharks of all sizes and a minimum of seven species. Cardeñosa means that this may very well be as a result of the sharks are feeding in an space of the reef that also has considerable meals as a result of it’s troublesome for fishing boats to entry it. Another cause, he says, is that native communities are complying with safety rules.

The second part of Global FinPrint started in December 2023, with plans to return to 26 international locations to assess the standing of sharks inside marine protected areas: areas inside the ocean the place authorities businesses have imposed limits on human exercise. The information ought to help nations in figuring out which areas nurture wholesome populations of reef sharks, and in designing new protected areas that achieve this.

Chapman and Cardeñosa each say they’re reasonably optimistic about the way forward for sharks on a worldwide scale, so long as science, public opinion and laws — and that laws’s enforcement — work collectively.

“There are definitely serious problems,” Chapman says. “But the good news is that we’re starting to get things right. In the United States, we’ve seen a recovery in sharks” — he factors, for instance, to elevated shark sightings in Florida after new laws. “We simply stopped killing too many and allowed them to reproduce,” he says. “My career goal is to help as many countries as I can to do similar things to improve the situation. That’s a long way of saying I’m hopeful.”

Cardeñosa hopes that his analysis will assist be sure that legal guidelines and agreements on shark safety are literally enforced. “The idea is that with our research, CITES can start to tighten the screws on countries and say, ‘Are you saying this is sustainable? Show us where you got it from,’” he says.

Conserving sharks is not only a nice-to-have, Cardeñosa provides. These fish are primordial beings which have been navigating by means of underwater landscapes for 400 million years, guided by senses we’re solely starting to perceive. Sharks assist keep the carbon cycle in the water by feeding on useless organisms, and will not directly contribute to the ongoing steadiness of photosynthesis in flowers by controlling species that feed on seagrasses. Keeping them in our oceans, Cardeñosa says, is vital.

Article translated by Debbie Ponchner

This story is a part of the Knowable en español collection on science that impacts or is carried out by Latinos in the United States, supported by HHMI’s Science and Educational Media Group.

This article initially appeared in Knowable Magazine, an unbiased journalistic endeavor from Annual Reviews. Sign up for the publication.