The intergovernmental body that regulates tuna fisheries in the Indian Ocean agreed to a suite of shark conservation measures, including rules to curb shark finning and the use of gear that causes significant shark bycatch. The new measures adopted by the Indian Ocean Tuna Commission, or IOTC, provide critical relief for a range of beleaguered shark species, but they may not be enough for some species, observers say.
“Sharks won for the very first time at the IOTC except the shortfin mako,” Iris Ziegler, head of fisheries policies and ocean advocacy at the German Foundation for Marine Conservation, told Mongabay. “For shortfin mako, it was a disaster. We are overexploiting the species, and it may never recover.”
The IOTC is a regional fisheries management organisation responsible for overseeing fishing of 16 species of tuna and highly migratory tuna-adjacent species like mackerel, billfish and swordfish. The body held its 29th session in Saint-Denis, La Réunion, an overseas department of France, April 13-17.
On the meeting’s agenda were a range of decisions related to conservation and management of the targeted tuna and tuna-like species. This year, shark conservation proposals featured prominently in the talks. An overlap in the aquatic habitats of sharks and tuna means that tuna fisheries capture a significant number of the threatened fish accidentally, as “bycatch”.
Sturdy as they appear, sharks are very vulnerable to overfishing. They grow and mature more slowly than other marine animals; for example, female shortfin makos (Isurus oxyrinchus) take nearly 20 years to reach sexual maturity. They have comparatively lengthy gestation periods; for example, blue shark (Prionace glauca) pups gestate for up to a year. Sharks also have few offspring, so when individuals fall prey to human actions, their communities take longer to recover from the losses.
More than a third of shark species globally face the threat of extinction. In the Western Indian Ocean, 40% of shark species are threatened.
Conservation-focused nonprofits that hold observer status at IOTC negotiations, like WWF, the Pew Charitable Trusts and the German Foundation for Marine Conservation, have long pushed for shark protections, lobbying the governments that sit at the negotiating table.
The IOTC’s member list includes coastal states that border the Indian Ocean, including countries in Asia and Africa. It also includes distant-water fishing nations that operate in the Indian Ocean, like South Korea, Japan and China, as well as France and Spain, which negotiate as part of the European Union delegation and, in France’s case, also via the La Réunion delegation.
Reducing shark bycatch
In the management of tuna fisheries, sharks are considered bycatch. However, some species are caught at such significant levels that conservationists like Ziegler argue they should be managed as target species. For example, blue sharks constitute more than 60% of the catch in swordfish fisheries in IOTC waters.
According to the IOTC website, “sharks are frequently caught in association with fisheries targeting IOTC species. Some fleets are known to actively target both sharks and IOTC species simultaneously”.
At the meeting, parties adopted a proposal for shark conservation sponsored by coastal states and a separate proposal for shortfin makos, an endangered species, sponsored by the EU.
Under the overarching shark conservation resolution, parties adopted a key measure on shark finning, expanded the scope of shark retention bans to include more species, restricted the use of harmful fishing gear, set guidelines to ensure sharks retained on fishing vessels are fully utilised and put in place reporting requirements for all shark species.
In the absence of rules or the presence of grey areas in management, fishers (both industrial and artisanal) profit from the sale of shark fins, which are used in traditional medicine and eaten as a delicacy in parts of East Asia.
The practice of chopping off a shark’s fins and discarding the animal at sea threatens shark populations. Not only do finned sharks dumped at sea almost always die either from bleeding or suffocation, but the practice also makes it very difficult to identify the species of harvested fins and, as a result, complicates efforts to identify, monitor and manage shark bycatch.
A key component of the new IOTC shark resolution is a requirement that all sharks be landed on shore with fins naturally attached to the bodies to prove the sharks were not finned and for better monitoring of shark bycatch. The requirement allows for alternative strategies, such as tagging fins and the corresponding carcasses, but storing them separately. After 2028, the commission will review the provision, and parties relying on alternatives must justify their continued use.
Currently, data on shark catches in Indian Ocean tuna fisheries are limited, and it’s difficult to gauge the health of shark populations. Up-to-date stock assessments exist for only two species: the near-threatened blue shark and the endangered shortfin mako.
Globally, more than half of all shark catches are blue sharks. While blue sharks are not overfished in the Indian Ocean currently, existing catch levels could result in the stock becoming overfished “in the near future,” according to the newly adopted IOTC shark resolution. The resolution puts in place a fisheries management system for blue sharks, the first in the Indian Ocean, with the IOTC expected to establish a total allowable catch and quotas for the species in 2026, according to Ziegler.
“For blue sharks, the management is starting, so blue sharks won,” she said.
A complete retention ban for oceanic whitetip sharks (Carcharhinus longimanus) and thresher sharks (family Alopiidae) was already in place in the Indian Ocean, meaning if fishers catch a member of these species they must throw it back in the sea, whether it’s alive or dead. Under the new IOTC shark resolution, a retention ban on whale sharks (Rhincodon typus) will come into force in 2026, provided the IOTC’s Scientific Committee endorses it.
Shortfin mako sharks
Conservation NGOs have called for a full retention ban for shortfin makos, which the IOTC says are overfished and subject to overfishing. But the newly adopted shortfin mako resolution includes only a partial retention ban for all vessels. So, fishers must return a shortfin mako to the sea if it’s alive when they hauled it onto the boat, but they can keep the shark if it’s dead so long as the vessel has an observer or an electronic monitoring system in place to verify the shark’s condition.
The major tuna fleets that pull in shortfin mako sharks are Spain (44%), Pakistan (25%) and Portugal (12%), according to the IOTC stock assessment for the species. Among the European fleet, longline vessels catch the most shortfin makos, while in Pakistan, small-scale fishers using gillnets catch the most.
Maciej Berestecki, the European Commission’s spokesperson for cohesion, reforms, environment and fisheries described the IOTC’s adoption of the EU’s shortfin mako proposal was a “notable achievement”.
On the question of Spain reporting high levels of shortfin mako catches, Berestecki pointed to the “the uneven availability of IOTC data across fleets.”
“Most of the other fleets catching shortfin mako are flagged in developing coastal countries and are composed of smaller and artisanal vessels with capacity constraints which restrain their ability to accurately report catch data,” he said in an emailed response.
Wire traces, also called wire leaders, are segments of fishing line near the hooks that are reinforced with materials like steel to prevent fish with sharp teeth from biting through and escaping, and they catch a lot of sharks. While the IOTC adopted new restrictions on the use of wire leaders, it isn’t a complete ban.
Parties agreed to stop using wire traces in the area north of the latitude 20 degrees south, but a lot of fishing goes on to the south. South Africa lies entirely south of this latitude, as does La Réunion. According to Ziegler, the Spanish longline fleet fishes mostly south of this latitude, so the wire leader exemption combined with the provisions of the partial retention ban would allow them to continue taking shortfin mako.
“This means EU vessels, because they have electronic monitoring systems, can retain it; nobody else can. The EU vessels can retain as much as they want because all of the makos they catch are dead because they use wire traces,” Ziegler said.
On the question of wire leaders, Berestecki said a full ban “would have a major economic impact on our long liner fleet. For this reason, the EU would be able to accept a full ban only on the basis of an undisputable scientific assessment based on clear data and provided an alternative to wire leader is available.”
He described the partial ban as “a pragmatic approach to the rational use of marine living resources.”
However, some observers said it won’t be enough to enable the species’ recovery. The “partial ban on keeping makos will better ensure they are not purposely caught and killed but is still likely to fall short of the scientific advice to reduce mortality by 60%,” Glen Holmes, a marine scientist and senior officer at the Pew Charitable Trusts, said in a statement emailed to Mongabay.
The new restrictions on wire leaders will take effect in 2028, provided no parties come up with research showing wire leaders don’t actually cause higher catch and mortality for vulnerable shark species than nylon monofilament leaders.
Tuna decisions
Most of the April meeting’s agenda was devoted to tuna species, the IOTC’s bread and butter.
In one key decision, the parties agreed that later this year they’d review a 2024 IOTC working party assessment that yellowfin tuna (Thunnus albacares) is no longer overfished. In 2015, the body declared the Indian Ocean yellowfin stock overfished and installed a rebuilding plan aimed at reducing catches to give the population a better chance at recovery.
But after nearly a decade during which fishers breached the plan numerous times, the positive assessment in 2024 drew some skepticism. In April, the IOTC scientific committee flagged “important uncertainties” about the data used in the 2024 yellowfin tuna assessment, in particular information regarding catch per unit effort, or CPUE, a measure of how hard it is to catch a species that scientists use to estimate its abundance.
“We have significant concerns over the seemingly miraculous recovery of the stock, given the decade of unrelenting overfishing that preceded the IOTC’s most recent yellowfin stock assessment,” Jess Rattle, head of investigations at the UK-based nonprofit Blue Marine Foundation, told Mongabay. Rattle attended the meeting as an observer. “We and many others have raised concerns regarding the data used and the transparency and independence of the new stock assessment. It is essential that these issues are resolved and that the assessment is reviewed and revised accordingly,” she said.
There was progress on other fronts too. Notably, the IOTC adopted catch limits for skipjack tuna (Katsuwonus pelamis) this year, so all three tropical tuna species — skipjack, yellowfin and bigeye (Thunnus obesus) – are now subject to these limits.
At the meeting, the commission also agreed on guidelines on how to implement management procedures for skipjack and bigeye tuna. These procedures make the process of sustainable fisheries management, for example deciding total allowable catch for a species, more automated and science-driven.
“This clear guidance is a welcome step forward, but there is a high likelihood that catch limits in each measure could again be breached. Members must work together to avoid the overfishing that has historically affected the region,” Holmes of the Pew Charitable Trusts said.
This article was first published on The Conversation.
