Why are we seeing so many sharks? When is it OK to hunt them?

Why are we seeing so many sharks? When is it OK to hunt them?
Top to bottom: oceanic whitetip shark, great hammerhead shark. Credit: Zach Christensen / Northeastern

When images of a dead 600-pound tiger shark hanging on an Alabama dock hit social media this summer, some people reacted with horrified dismay.

But others applauded the Alabama Deep Sea Fishing Rodeo for reviving the shark hunting category after a seven-year hiatus.

They say that once declining have rebounded to the extent the apex predators threaten to become a nuisance fish if they are not hunted and fished in turn.

"It's all about who you ask. Which is a weird thing to say in science," says Northeastern University Ph.D. student Evan Prasky.

It's his job to help sort fact from fiction in order to develop policies that protect the ecosystem and promote the long-term sustainability of the fishing industry and fishing stocks in the Gulf of Mexico.

The goal is to quantify the amount of fish caught by fishermen that end up being wholly or partially consumed by sharks, a practice known as depredation, to determine whether anglers need to change their behavior or whether it's okay to hunt certain , Prasky says.

Working under advisers Steven Scyphers at Northeastern and Marcus Drymon at Mississippi State University on behalf of the National Oceanic and Atmospheric Administration, Prasky surveyed 1,000 in Florida, Alabama, Mississippi, Louisiana and Texas about their interactions with sharks and what role sharks play in fish depredation.

"The results are kind of interesting," says Prasky, who also conducted in-person interviews of fishermen coming off their boats during the Alabama Deep Sea Fishing Rodeo in July.

Recreational fishermen who head out once or twice a year are thrilled by the sight of a shark, even if it's grabbing their fish off the line.

"You are watching one of the greatest spectacles in nature unfold in front of you," Prasky says.

Fishermen who head out more frequently, up to four times a week, "have wildly different views," he says. "Their views are that depredation is disrupting their livelihood."

It certainly seems as though the seas are boiling with sharks this summer.

A hammerhead was caught on video fishing right at the water's edge in Nantucket, six people were bitten by sharks—none seriously—off Long Island and so many great whites are being spotted off Cape Cod on the Sharktivity app that it sometimes appears they might be developing their own traffic jam.

Fishermen have a laundry list of complaints about the tiger, bull, sand and other sharks that patrol the warm waters of the Gulf of Mexico, from biting through lines to bending hooks on a regular basis, Prasky says.

"Hooks and (other gear) aren't cheap, especially if a shark keeps biting them off. It can be expensive."

U.S. bans on shark finning—taking the fins and discarding the body—and laws against hunting great whites have in recent decades offered protection to shark species in the U.S.

But most populations "are not rapidly growing," Prasky says. He says anglers who want to hunt for the dusky sharks and sandbar sharks that prowl Gulf fishing grounds will be disappointed since the animals are on a centuries-long rebuilding program.

Fishermen "are saying there are too many of these sharks. We know you're encountering them, but they only have one pup a year, maybe every two years," Prasky says. He says part of the issue is that more people are fishing than ever.

Why are we seeing so many sharks? When is it OK to hunt them?
Top to bottom: scalloped hammerhead shark, tope shark, shortfin mako shark. Credit: Zach Christensen / Northeastern

Anglers and sharks also converge at artificial reefs, which people are allowed to purchase in Alabama and Florida to use as their own secret fishing spots.

But the reefs are no secret to sharks who enjoy the fishy buffet on offer, Prasky says. "Sharks are learning it's an easy meal."

The increased use of social media to post videos and photos of sharks also adds to their visibility, he says.

According to the NOAA Fisheries site, only one shark in U.S. waters—the oceanic whitetip shark— is considered threatened while the scalloped hammerhead is considered endangered under the Endangered Species Act.

Scientists say the designations are region specific, and the sharks are not threatened or endangered in the Gulf of Mexico, where the scalloped hammerhead can be harvested for both recreational and commercial purposes.

NOAA officials are currently reviewing petitions to add the shortfin mako in the Gulf and Atlantic fisheries and the tope in the Pacific to the endangered or threatened list, and in June the agency received a petition to include the great hammerhead on the list.

Other organizations, such as the International Union for the Conservation of Nature (IUCN), maintain separate, longer lists of sharks they consider imperiled, including the tiger shark, which it considers near threatened, and great white and bull sharks, which it considers vulnerable.

IUCN reports that sharks are in danger around the globe, with more than 30% of shark species and their relatives currently being at risk of extinction, according to Pew Trusts. Pew says that an analysis of the Hong Kong shark fin trade shows up to 73 million sharks are killed every year.

Some activist groups such as the California-based Shark Allies want fishermen to take a hands off approach to sharks and compare shark fishing tournaments to big game trophy hunting.

"Protection only happens once someone rings the alarm bells about a species disappearing. Unfortunately, by that time it is often so far gone that recovery is difficult and a very lengthy process," says Stefanie Brendl, founder of Shark Allies.

"While some people might not like the idea of sharks coming back to our waters, they are an extremely crucial part of the intricate balance in the ocean. They fulfill a job that we cannot replace with any or technology," Brendl says.

"Sharks do these amazing things," Prasky says. "They essentially balance ecosystems. They take out the weak, they take out the sick."

Sharks are critical components of healthy oceanic ecosystems, in the same way that lions are critical parts of healthy terrestrial ecosystems, he says.

The animals' star power is evident in objections on to the taking of a tiger shark during the Alabama Deep Sea Fishing Rodeo, billed as the world's largest fishing tournament.

As charismatic megafauna, sharks inspire a depth of passion not common with smaller aquatic species, Prasky says. "It's a lot easier to advocate for a shark than a sardine."

He doesn't expect his research, being conducted in concert with NOAA's Restore Program in the Gulf of Mexico, to be published until 2023.

Ultimately the science "could lead to a deeper understanding of this human-wildlife conflict, which will lead to better management," Prasky says.

The science could also lead NOAA officials to advise Gulf to accept a "new normal" and change their behavior when it comes to fishing times, seasons and species, Prasky says.

"Anglers are excellent at adjusting their fishing tactics to changing conditions."

Citation: Why are we seeing so many sharks? When is it OK to hunt them? (2022, August 22) retrieved 21 April 2024 from https://phys.org/news/2022-08-sharks.html
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