Sea change: no respite for whitetip sharks in the Pacific

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Oceanic whitetip shark (Carcharhinus longimanus). Image by Cvf-ps via Wikimedia.

Whitetip sharks are declared critically endangered,
but they gain no protections in the Pacific

by Monica Evans — Mongabay
  • This past week, the International Union for Conservation of Nature classified oceanic whitetip sharks (Carcharhinus longimanus) as “critically endangered,” citing “steep population declines” in all oceans.
  • The Western and Central Pacific Fisheries Commission, a multilateral body, manages fisheries in a vast swath of the Pacific Ocean, including the large and lucrative tuna fishery that accidentally kills tens of thousands of whitetips each year.
  • Whitetip sharks are predicted to become extinct in the western and central Pacific under current management practices, their numbers having declined there by around 95% since 1995.
  • The commission met this month in Port Moresby, Papua New Guinea. It adopted several conservation measures, but took no new steps to protect whitetip sharks, as many scientists and conservationists had hoped.

The oceanic whitetip shark was reclassified as “critically endangered” by the International Union for Conservation of Nature (IUCN), citing “steep population declines” in all oceans. That represents two big steps toward extinction from the shark’s previous classification as “vulnerable,” which it had held since 2006.

However, that wasn’t enough to convince countries that fish for tuna in the western and central Pacific Ocean to step up protections for the species in that region, where scientists predict the sharks will disappear if current management practices don’t change.

Many scientists and conservation advocates were hopeful that the 16th meeting of the Western and Central Pacific Fisheries Commission (WCPFC), held from December 5 to 11 in Port Moresby, Papua New Guinea, would commit to new steps to boost the region’s population of whitetips (Carcharhinus longimanus). The multilateral body manages fisheries in the vast region, including the large and lucrative tuna fishery that accidentally kills tens of thousands of whitetips each year.

At the meeting, delegates finalized and adopted a new conservation and management measure for sharks, which may help other species. But the measure doesn’t offer any new protections for whitetips, and their particular plight in the region didn’t make it onto the agenda.

“The Commission’s annual meeting was the first real opportunity for the member states to act on these alarming findings,” said a statement issued by the NGO WWF after the meeting. “Unfortunately, they did not rise up to the challenge. The tragic situation of the oceanic whitetip shark was not substantially addressed during the meeting, with no opportunity to even consider a much-needed recovery plan as a solution.”

CHOMP!
Oceanic whitetip shark (Carcharhinus longimanus). Image by Andy Mann.

Dramatic decline

Oceanic whitetips were once among the most common pelagic shark species in the tropics. As apex predators, they play a crucial regulatory role in marine ecosystems, maintaining balance and diversity in the species below them in the food web. Sharks are also culturally important for many Pacific peoples, often seen as manifestations of ancestors, deities or guides for ocean-goers.

But a recent stock assessment commissioned by the WCPFC revealed that the oceanic whitetip population in the western and central Pacific Ocean has declined by about 95%. The assessment concluded that if new measures aren’t taken to protect the sharks, the population will become regionally extinct.

Why? The region’s oceanic whitetips are “overfished and undergoing overfishing,” according to the assessment. And it’s mostly by accident.

Whitetips are often caught by longliner boats fishing for tuna, because they swim close to the surface and are attracted to the longliners’ lures. Less commonly, they’re caught by purse seiners, which enclose all the fish in an area in a large net that’s drawn tight at the top and bottom. Whitetips are considered bycatch, a term for species that are caught accidentally, and to date there are no catch limits in place for them.

Like most sharks, whitetips take a long time to reach sexual maturity and have small litters of pups every year or two, so they are vulnerable to overfishing. “It’s very, very simple, we’re taking them out faster than they can replenish themselves,” Demian Chapman, a shark conservation expert at Florida International University, told Mongabay.

Demand for whitetips’ large fins, which fetch high prices as an ingredient in shark-fin soup, a prized dish in many East Asian countries, has also contributed to whitetips’ decline. To mitigate this, in 2011 the WCPFC enacted a “catch and retention” ban, making it illegal for fishers to intentionally catch whitetips and requiring them to immediately release any they catch accidentally — with their fins still attached. Then, in 2013, parties to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) passed restrictions that severely limited the legal trade of whitetip fins.

The stock assessment found no evidence that fisheries are currently targeting whitetips in the region. “But we know that there is still a fin trade of this species, for sure,” said Chapman, who has researched the trade in Hong Kong and China, “and probably a good amount of it is illegal.” This suggests that some fishers are still opportunistically selling the fins of the sharks they catch.

Keeping whitetips off the lines

According to the assessment’s authors, the WCPFC’s existing measures “may have had a positive impact on stock status by decreasing fishing mortality.” But they also acknowledged that some fishers and observers had not updated their identification, recording, and surveillance practices since the 2011 catch and retention ban took effect, so some whitetip catches may have gone unrecorded or been incorrectly identified, compromising the data used in the assessment.

Keeping more whitetips alive remains a “pretty major conundrum,” said Chapman, even for researchers at the forefront of the issue. “The problem is that a decent proportion of the whitetips still die when they’re caught,” he said.

He identified three ways to boost the survival rate of the species. The first is keeping sharks from getting stuck on longlines. Discouraging them from taking the bait, for example by attaching magnets to the hooks, which sharks find irritating, is one option. Ensuring that lines are made from material that sharks can bite through to free themselves, such as nylon rather than wire, is another.

The second is to maximize the survival of whitetips that do get hooked by training fishers to free them safely. Chapman said that steps such as keeping sharks in the water while they’re being released and cutting the line right at the hook so they don’t swim off trailing gear have made a big difference for whitetips in Atlantic tuna fisheries. Leaving longlines in the water for shorter time periods is also effective, he said.

“Whitetips are quite tough,” said Chapman, “so when they get hooked, they can handle struggling on the line for a while. There’s definitely a relationship between how long the longline was soaked and how many whitetips come up dead or in very poor condition.” The downside is that shorter soak times entail more work for fishers and may also reduce tuna catches.

The third and most radical method Chapman identified is to simply avoid setting longlines in places where whitetips are relatively common. That’s also a challenging prospect for tuna-fishing nations, he said, “because the whitetips are pretty closely correlated with the oceanographic features that would also attract tuna.”

But economic impacts like these are no reason not to act, said Chapman.
“We’ve left it so long with these species that now it’s pretty drastic. This is the problem: we tend not to act until the grim reaper is on the doorstep, and that’s where we find ourselves with the whitetip in this region,” he said. “These measures are going to hurt, probably, but this is because we kicked the can too far and let them drop and drop and drop, and now it’s critical.”

Andy Cornish, who leads WWF’s global shark and ray conservation program, also emphasized the urgency of the situation. “With the population pushed to the brink of extinction, there is no time to waste,” he said in the organization’s closing statement. “WCPFC nations will not have another chance to introduce new measures to start recovering the population until the next Commission meeting in a year’s time.”

At the meeting, WCPFC took a number of new measures to better manage fisheries in the region, such as adopting voluntary guidelines for how fishers should safely free seabirds caught on longline hooks; adopting a work plan to boost albacore stocks; banning the catch and retention of manta and other mobula rays; and adopting a resolution to consider the impact of climate change on its work.

She bit on a fish hook and got away, but it really hurt. Her baby bit a fish hook and didn't get away, so now she's out for revenge. She swimming after you as you sleep. Sweet dreams!
Oceanic whitetip shark (Carcharhinus longimanus). Image by Alexander Vasenin via Wikimedia.

Monica Evans is a freelance writer based in Aotearoa, New Zealand, who specializes in environmental and community development issues. She has a master’s degree in development studies from Victoria University of Wellington. Find her at monicaevans.org.

 

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