OCEAN PLUNDER: Relentless fishing and dodgy science — Spain and Taiwan’s blue shark trade

Refrigerated container trucks are backed up against the Hermanos Fernández Ibáñez fish-processing factory, a bit outside of the Spanish port city of Vigo. Workers open the truck’s doors and, in the near-freezing air, use long fish hooks to pull out clusters of frozen blue sharks and swordfish. All of the sharks are headless. The sharks hit the concrete floor and scatter like a handful of thrown unlucky dice.

Workers cut off the fins, separate the 15 tonnes of blue sharks by weight and then skin them using two-handed drawknives. If they are not stored in the -25°C to -50°C warehouse, the sharks are cut up into loins and small cubes, which are sold in European supermarkets. 

The business model for the Spanish shark fishing industry is fairly straightforward: catch the sharks in the Atlantic, Pacific and Indian oceans and sell the meat either inside Europe or to countries such as Brazil and Morocco. The fins and skins go to Asia, where Singapore acts as a major trading hub.

Claudio Ibáñez is in charge of the factory, his grandfather started the business back in 1940, and he sells the shark meat for between R28 and R37/kg and the fins for R280/kg. With the sale of both the meat and fins, each individual shark brings in a revenue of R56/kg. By way of comparison, he gets R93/kg for swordfish, a price he describes as “very cheap”.

Hermanos Fernández Ibáñez isn’t just a fishing processing company, it also has two longline fishing vessels, both of which are currently in the Pacific. Swordfish and blue sharks are caught on the same long lines with the same hooks. The boats stay out in the oceans for years and the crews are flown back to Spain for rotation. The swordfish and blue sharks are landed in foreign ports and shipped to the processing plant in containers. Hermanos Fernández Ibáñez is right at the start of the blue shark value chain.

Ibáñez explains that the company started fishing swordfish 35 years ago. He says that “at that moment we didn’t appreciate the blue shark. Year by year we were catching some blue shark.”

He explains that at first the price for blue shark was very low. Over time it started to rise to the point where, starting 15 years ago, the blue shark fishery is now, as Ibáñez puts it, “a very good complement to the swordfish fishery.” 

In fact, Hermanos Fernández Ibáñez relies on combining the blue sharks and the swordfish fisheries since neither is economically viable on its own. And the company is not alone in fishing for blue sharks. Far from it. 

Taiwanese and Spanish fleets catch blue sharks in great numbers.

A species we never used to fish

Blue sharks are a pelagic species found across the world’s oceans and they are one of the most abundant shark species. While their diet ranges considerably, cephalopods such as squid and octopus are an important food source. Blue sharks are the most fecund species of shark: females have litters of 34 pups on average and reproduce annually. That said, blue sharks reproduce more slowly than bony fish and the fecundity of bony fish is proving to be inadequate to compensate for overfishing – 12.7% of all bony fish species face extinction.

While great white sharks, orcas, tiger sharks and some sea lions predate upon young blue sharks, human beings are by a long way the main predators of both juvenile and adult blue sharks. According to FishStat, a specialised database belonging to the Food and Agriculture Organization of the United Nations (FAO), 119,820.62 tonnes of blue sharks were caught in 2024.

Of that, Spain caught 45,374.92 tonnes (37.8% of the global catch) and Taiwan 31,890.38 tonnes (26.6%). While no other country comes close to these tonnages, countries like Peru and Namibia play important transit roles. Walvis Bay in Namibia, for example, is an important port for Spanish fishing companies to land and process blue sharks. In 2024, Spain imported 1,725.35 tonnes of blue shark with a value of R30-million from Namibia.

By its own admission, the FAO’s total catch figures are heavily reliant on records from industrial fishing fleets. Discards at sea, small-scale fishing, recreational fishing and other activities are often not recorded. To rectify this and provide an accurate account of fishing, the marine biologist Daniel Pauly formed the organisation Sea Around Us in 1999. 

Using additional data sources, they were able to re-analyse the data from 1950 to 2019 and concluded that fishing catches in general were 50% more than what reported catches indicate. The peak year for the total global catch of all species was 1996. 

The difference between the Sea Around Us findings and the FAO’s reported blue shark catch is considerable. For the 2019 catch, Sea Around Us concluded that a total of 347,229.31 tonnes of blue shark were caught, considerably higher than the FAO’s figure of 109,982.24 tonnes.

The point worth remembering here is that official reported landings don’t represent the actual level of blue shark fishing and of fishing in general.

For example, a study by Hoang Huy Huynh of the National Kaohsiung University of Science and Technology in Taiwan and three other scientists states: “In the Indian Ocean, reported blue shark landings averaged 26,691 tons annually from 2015 to 2019. However, actual catches are likely to exceed 55,000 tons due to inadequate monitoring, misreporting, and illegal, unreported, and unregulated (IUU) fishing.”

A consulting firm, Poseidon, used an estimated average weight of 27kg per shark landed – those sharks that avoid longliners’ hooks and grow to adult males typically weigh between 27kg and 55kg, females between 93kg and 182kg – to arrive at a figure of seven million blue sharks caught in 2019. Poseidon also estimated that the 2019 value of blue shark meat and fins was R6.6-billion.

Using the same average weight and the FAO’s catch figure, we come to the very conservative figure of 4.4 million blue sharks caught in 2024. But that’s not the most startling fact coming out of the FAO’s data. We never used to fish blue sharks at any kind of industrial scale.

In 1950, only one country reported landing blue sharks. Indonesia recorded 47 tonnes and remained the only country fishing them until 1978 when France landed four tonnes. Spain started fishing blue sharks in 1997, landing 29,917 tonnes. Taiwan’s reported catch came a decade later, a haul of 3,399 tonnes. What the data clearly shows is that 1997 was the year when the large-scale industrial fishing of blue sharks kicked off and the Spanish were at the forefront with 75.7% of the total landed catch.

Daniel Pauly, a professor at the University of British Columbia, predicts that the “shark fishery is not going to last long, two decades, perhaps two decades, and then it’s gone”.

After the collapse of the blue shark fishery, Pauly says that “we will start fishing something else. For example, mesopelagics, lantern fish and so on.”

The International Union for Conservation of Nature and Natural Resources (IUCN) placed blue shark on its Red List in 2018, giving the species a “near threatened” designation. In 2022, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) added blue sharks to its Appendix II listing, which means countries now have to issue export permits.

CITES’ description of the classification is: “Appendix II lists species that are not necessarily now threatened with extinction but that may become so unless trade is closely controlled.”

The IUCN declared in 2024 that blue sharks were “largely depleted”. Its assessment states: “In the long term, with maximum conservation effort, the species’ condition could improve significantly… Achieving this would require strict enforcement of catch limits and a temporary suspension of large-scale commercial fishing in the Mediterranean.”

Back in 2016, the IUCN designated Mediterranean blue sharks as critically endangered, with a population decline of up to 90% over 30 years due to overfishing.

Verdesca alla mediterranea, a well-known Italian dish, is made from blue shark and a simple Google search throws up all kinds of recipes: for example, Elena Terrile’s cooking website, Cucina con Nenè, punts a recipe, as does the Italian frozen food company Emme Gel.

Spain caught two and half tonnes of Mediterranean blue sharks in 2024, according to the FAO. 

Tossing a coin

Angela Cortina is in her office at the Fishing Vessel Owners’ Cooperative of the Port of Vigo (AVRI), an association representing 200 fishing boats. Out of those 200 boats, 30 are longliners that target both swordfish and blue shark. She says that while 2,200 people are directly dependent on swordfish and blue shark, the European Union doesn’t care enough about the industry, which is threatened, in her view, by foreign competitors operating under weaker environmental and labour standards.

She shows us a glossy cookbook featuring dishes such as marinated blue shark carpaccio and grilled blue shark with citrus vinaigrette, apple and pomegranate. ARVI runs an annual seafood festival in Vigo, which promotes blue shark meat, among other marine food sources.

Blue shark, she says, is “tasteless, basically. The good thing about it is that you can make it taste like you want. It’s fishy but it’s not a very strong taste.”

Cortina is adamant that the Spanish fleet’s blue shark catches are tightly controlled and are ecologically sustainable. According to her and because of their fecundity, blue sharks “recuperate very quickly. They’re very resistant and very resilient as a species. That’s been known and monitored by scientists for a long time. So we know that.”

She adds: “Sometimes it’s problematic because they reproduce so fast and they prey on other species, on smaller fish. If they are in the longline, they will go for the swordfish. So the species is monitored in every area of the world.”

The regional fishing management organisation (RFMO) for both the North Atlantic and Southern Atlantic is the International Commission for the Conservation of Atlantic Tunas (ICCAT) and its sets quotas for blue shark: a total allowable catch of 30,000 tonnes for the North Atlantic and 27,711 tonnes for the South Atlantic. The European Union is granted the bulk of the quota, getting 62.8% of the South Atlantic quota and 82.6% from the North Atlantic.

One important thing to note about the Atlantic quotas is that they are higher than the current level of fishing in the Atlantic. In other words, the quotas are not restricting blue shark fishing and future increases in the level of fishing are entirely possible.

The situation is a bit different in the Indian and Pacific oceans, where both Spain and Taiwan fish hard. The RFMOs for these areas have not set quotas, so it’s open season on the sharks.

The individual RFMOs for the Pacific, Indian and Atlantic oceans all state that their blue shark fisheries are sustainable according to science – that there is no danger of the stock collapsing like so many other fisheries have done – and this is where things become murky, complicated and downright surreal. 

The basic process of determining the sustainability of the fisheries is that a scientific committee attached to each RFMO assesses the stock and then makes recommendations to the countries that constitute the RFMO. These countries then make a consensus-based decision on the recommendations. If any one country disagrees with the recommendations, they won’t be taken up. 

Practically speaking, this means that setting a quota, changing a quota limit or instituting some other fishing restriction is difficult because of competing interests between countries and a strong desire to protect national fishing industries.    

In essence, the decisions on what an RFMO should or shouldn’t do is the product of often long political negotiations between countries and some of whom, such as China and the US or the EU and Russia, have severe geopolitical differences.

The ongoing discussion within ICCAT to strengthen the fins-attached rule is a prime example of how slow the decision-making process can be. Meant as a measure to stop sharks being caught at sea, definned and the carcasses thrown overboard, the present mechanism (an onboard fin-to-carcass ratio) is largely seen as inadequate. Proposals to change the rule so that all sharks caught must have the fins attached when landed are now in their 17th year of discussion at ICCAT, with no consensus in sight.

The FAO held a workshop in October 2025 for scientists working on blue shark fisheries. Several of the participants were associated with RFMOs. The workshop’s minutes indicate clearly that there are significant data problems. The minutes state “that across RFMOs there are widespread issues with both the quantity and quality of catch data… and with uncertainties in key biological parameters.”

The minutes further state: “Blue shark stocks are generally considered data poor, with limited composition data in many regions and catches frequently not reported at the species level (e.g. catches often aggregated as ‘shark’). Nominal catches are believed to be underreported, and estimates of unreported catch are often extrapolated based on limited data and broad assumptions.”

Given the lack of data, how then do RFMOs declare that blue shark fishing is sustainable? What does happen is that RFMO scientific committees provide probabilistic assessments for the state of the stock. ICCAT held a crucial meeting in November 2025 where 54 countries met to decide upon the fate of tuna, blue sharks and other species in the Atlantic.

The scientific committee noted that 93% of total accumulated shark catches were blue sharks. Based upon a stock assessment done in 2023, the committee stated in 2025 that North Atlantic blue sharks had “50.1% probability of being overfished”. For the South Atlantic, the committee states that there is a “54.5% probability of overfishing”.

These probabilities are sufficient for ICCAT to declare the blue shark fishery sustainable. 

But to take a 50% bet on one’s pension, the children’s university fund or the mortgage would be highly unwise. Yet this is what ICCAT is doing. Throwing the dice and hoping for even.

As Daniel Pauly says of the probability: “People that are willing to accept 50% are not guided by science.”

Iris Ziegler represents Deutsche Stiftung Meeresschutz, an NGO that has observer status at both ICCAT and the RFMO for the Indian Ocean. She’s a scientist and, in terms of being safe from overfishing, she says: “I would really want to see a higher probability for sharks – ideally at least 70% probability and having such a probability both in the near future and in the longer-term perspective.”

Luis Gustavo Cardoso is the vice-chair of ICCAT’s scientific committee. In response to Daily Maverick’s query about whether the 50% probability threshold was scientifically rigorous, his written reply was: “A framework calibrated only to very high certainty thresholds would systematically under-use a renewable resource capable of meeting food security needs sustainably – so the 50% convention for describing current status, combined with the precautionary buffers applied in forward-looking catch advice, is the balance the science is designed to strike.”

For the Mediterranean, where blue sharks are caught as bycatch, Ziegler would like to ban fleets from retaining the sharks. The sharks would have to be returned to the sea alive. There would also have to be, in her view, strict controls to reduce bycatch mortality.

Ziegler also states that there needs to be a “quota for blue sharks for the fishing nations in all ocean basins” and the setting of total allowable catch limits for each fishery. The Indian Ocean, which is administered by the Indian Ocean Tuna Commission (IOTC), is an example of how far away that goal remains. Blue sharks fall under the IOTC’s mandate.

A 2025 IOTC scientific assessment of the stock states that “maintaining current catches is likely to result in decreasing biomass and the stock becoming overfished and subject to overfishing in the near future”. The assessment also notes that there are no “harvest control rules for any shark species”.

At an IOTC meeting in 2026 to discuss the stock status, only one country put forth a proposal in regards to catch limits. Japan’s proposal was to postpone the entire discussion on blue shark catch limits and to remove a bycatch mortality prevention measure. Accordingly, no quota was set. 

In other words, the countries of the IOTC chose not to act upon the advice of IOTC scientists to limit blue shark catches even in the face of looming overfishing.

In the North Pacific and based upon a 2022 stock assessment, the probability of not being overfished is 62%. New assessments are planned for the North and Southwest Pacific in 2027. According to the FAO, both of their current stock assessments suffer from data issues and uncertainty. 

Interestingly, the FAO also states that in the Southwest Pacific the “highest catches (by numbers) occur around New Zealand and Tasmania, where most landings are juveniles and small individuals”.

There has yet to be a stock assessment for the Southeastern Pacific.

The Pew Charitable Trusts is another accredited NGO observer at ICCAT and the Pew’s lead at ICCAT is Esther Wozniak. She’s been attending official ICCAT meetings for the past seven years. Of the probability factor, she’s in agreement with Ziegler and would like a 70% probability of not being overfished.

Despite probabilities being lower than 70% in key blue shark fisheries, Wozniak is not in favour of instituting quotas across all blue shark fisheries at the moment, stating that quotas have to be a “science-based process. Because if we as an organisation just go and tell them [RFMOs] you have to close the fishery, it’s not going to be very well received… they want the recommendation itself to come from their own scientists.”

Asked about the independence of the scientists at RFMOs, Pauly says “they are not independent. Most of them are hacks that are put there by the countries [to] enable them to have a high quota. The RFMOs don’t contribute much to rebuilding any stock and they contribute to the overall fishing scene.”

He adds: “Essentially my view of fisheries is that any fishery is potentially committing suicide. It’s like a guy running around with a knife and you have to prevent [him] from stabbing himself.”

The Indian Ocean Tuna Commission and the Western and Central Pacific Fisheries Commission did not respond to Daily Maverick’s queries regarding the sustainability of their blue shark fisheries.

The Pew Charitable Trusts engages with the General Fisheries Commission for the Mediterranean (GFCM). On the proposition that there should be a quota for blue sharks in the Mediterranean, Wozniak says: “I think GFCM as a body under FAO has done a good job of increasing their overall assessment and trying to figure out which species are in decline and which species are doing better. And I think there’s more work to be done on blue sharks there.”

The General Fisheries Commission for the Mediterranean recently published The State of Mediterranean and Black Sea Fisheries 2025. Out of 204 pages, blue sharks are mentioned only three times. The report labels blue shark catches as ‘incidental’ or cases of bycatch and declares that blue sharks are exposed to “fishing pressure”. 

But the science on the Mediterranean is in and there is no doubt. The IUCN is an independent scientific organisation and is free from the control of fishing nations. It is charged with determining which species are heading towards extinction and it clearly states that the blue shark “population in the Mediterranean is declining at a critical rate and exists in an extremely depleted state”.

In fact, the research findings have been there for years so there is no excuse not to advocate for and implement drastic measures. Along with two other authors, Pauly wrote in a 2019 paper on the Mediterranean: “Following centuries of exploitation and the more recent expansion and intensification of fisheries, elasmobranchs [sharks, rays and swordfish] have become increasingly rare, with precipitous population declines.”

One cannot conserve a species by continuing to kill vast numbers of that species.

The General Fisheries Commission for the Mediterranean did not reply to Daily Maverick’s queries concerning blue shark conservation measures.

Since, and by common agreement, the blue shark fisheries are data poor, there is an urgent need to rectify the situation. According to both the FAO and the scientific committees of the various RFMOs, there is a better system of monitoring blue shark stocks than doing a stock assessment and having a political negotiation. A better system that isn’t being implemented, confounded with country disagreements.

And farewell to the fish

Blue sharks are winched up in bunches from boats at the Taiwanese port of Donggang, a four-hour drive from Taipei. The fins are attached to the bodies, as per Taiwanese regulations. The sharks are put down on the concrete pier, small front-end loaders collect the bodies and place them in refrigerated trucks. 

While the whole process is fast and well practised, the sharks aren’t the star of the show. That’s yellowfin tuna, a far more valuable fish than the sharks, and there’s a row of restaurants right next to the pier selling tuna sashimi. As with swordfish, blue sharks are caught alongside yellowfin tuna.

Prices at Donggang for blue shark meat are between R10 and 13/kg. Fins go for R240/kg. The North Pacific is where Taiwan fishes the hardest for blue sharks: Taiwan caught 26,462 tonnes in 2024 – its record catch for 2009-2024.

A relatively new method for assessing the health of a fishery, one that is used in some tuna fisheries, has a name that will get a bureaucrat excited: a management strategy evaluation. As is inevitable in the technical world of fisheries management, there’s an initialism, MSE.

An MSE is a dynamic process where data from a fishery is compared to a series of objective parameters. The parameters could be female-male ratio of catches, size of individuals caught, the level of fishing, catch maximisation or something else. If the data indicates that the parameters are breached, corrective measures such as bans on fishing at certain times of the year or decreasing the quota kick in. Countries don’t negotiate the corrective measures, the MSE institutes them.

The FAO is fully supportive of MSEs for blue sharks. Asked what would happen if MSEs weren’t implemented, Wozniak says: “I think it will be a very bleak future for the blue sharks.”

At this juncture, a note of caution. An MSE isn’t a magic wand that will restore blue shark populations or replace the lack of data. 

Kwang-Ming Liu retired from his position as professor of marine affairs and resource management at the National Taiwan Ocean University in 2025. He says of the MSE: “I don’t think this management measure can be applied for data-limited shark species in the Pacific now. A precautionary catch quota for certain species may be a more practical approach.”

Liu also points to the need for a broader conservation measure: “A reduction of fishing effort for tuna fishery may ensure the sustainability of tuna species and the bycatch (sharks).” 

Unlike in the Pacific, the Atlantic fisheries have quotas and ICCAT has been trying to implement an MSE since at least 2024. However, the MSE’s objectives still haven’t been set for the Atlantic. At this year’s critical ICCAT meeting in April, the European Union’s proposal on objectives couldn’t find consensus. Even more broadly, there were disagreements about the nature of the MSE. 

ICCAT is not an entirely transparent organisation and minutes of its meetings don’t name the countries involved. Instead, countries are blandly called CPCs and hiding behind an initialism, it could be said, is a way to avoid public disclosure.

From the minutes of the April 2026 meeting, we do know that one country wanted to prioritise an MSE for short-fin mako over blue sharks, with the reasoning that the MSE for short-fin mako was already delayed. Others wanted to do both species together. Another wanted to do the blue shark MSE before the one for short-fin mako. Several were concerned about the number of MSEs being conducted.

The upshot is that the discussion ended without consensus and no blue shark MSE objectives were set. Further discussions are slated for an ICCAT meeting in November 2026.

The danger is that lack of agreement causes delays in implementation. ICCAT’s own internal documentation states that delays increase “the risk of the 2023 assessment data becoming outdated. If the MSE is postponed significantly, the cost of reconditioning models or restarting after a new assessment becomes unavoidable, effectively resetting the process.”

According to Zeigler, the next ICCAT stock assessment should be in 2028. If there are delays in the MSE implementation or an MSE doesn’t happen by then, the countries at ICCAT will begin a round of political negotiations over the 2028 stock assessment.

In effect, preventing the MSE for blue sharks is achievable simply by delaying the MSE’s implementation.

The eminent fisheries scientist John Gulland comes to mind at this point. He once said: “Fisheries management is an interminable debate about the condition of fish stocks until all doubt is removed. And so are all the fish.”

Integrity

The Kanziding fish market in Keelung, a port city in Taiwan’s north, only starts at one in the morning. Vendors set up their wares at the sides of the downtown streets and people fill the roads, browsing and shopping. The variety of marine species is staggering. Blue-spotted parrotfish, squid, pacific cutlassfish, frozen Norwegian salmon, yellowfin tuna and so many others – a veritable undergraduate degree in marine biology. Here and there you find blue sharks.

A customer speaks to a vendor who then places a blue shark, sans head or fins, down on the washed concrete floor. The fishmonger carefully examines the carcass, figuring out the ideal cut. The customer walks away with a fair bit of shark in a transparent bag. In Taiwan, fish markets have an honesty often not found in the West. Marine products aren’t sanitised in supermarket vacuum packs, processed into anonymised cubes and loins. You see exactly what you are buying in Taiwan and markets like Kanziding are the end points of the blue shark value chain.

Blue shark meat at Kanziding goes for R126/kg and in wealthy and expensive Taiwan that’s a bargain. Fins aren’t sold at Kanziding. Instead, they’re at stores specialising in ingredients for high-end cooking and Chinese traditional medicine. Top-quality blue shark fins can go up to R20,000 a kilo. 

Chin-chang Wu pours green tea and has an old-school politeness about him. Blue shark fins are in a glass cabinet to the side of his desk and a little bit further, closer to the entrance, there’s a bag of dried blue shark skin. Seventy years ago, Wu’s father opened the store, which is in the southern city of Kaohsiung.

Shark fins are no longer the sales item they used to be and he has no new stock. Wu says: “Young people now eat less shark fin. Young people aren’t like the older generation, who liked eating shark fin. That’s gone now. So demand has fallen. That’s the first thing. Second, when their parents want to buy shark fin, young people will scold them.”

“This line of business,” Wu adds, “is gradually disappearing. The margin isn’t good.”

His biggest sellers are abalone, dried scallops, mushrooms and fish maw (swim bladder), and he’s adamant that his business isn’t dependent on fins. If customers want fins and the trade remains legal, he’ll sell fins. If he can’t sell, either from dropped demand or changes in the law, his store will go on just fine.

Asked about a quota for shark fishing, Wu says that “if shark output keeps falling, I support it, protecting sharks. If the scientists, the professionals, think sharks have declined, then I think reducing it is reasonable.”

The large red Chinese characters behind his desk translate to integrity.

A rigged game

And this is where we are at. Decisions on quotas and harvest restrictions are being made on politics and on the basis of extremely limited data, broad assumptions and reckless probabilities. Despite IUCN warnings, a CITES listing and the collapse of the entire Mediterranean shark fishery, RFMOs and nation states are acting as if blue sharks are an inexhaustible resource. The absurdity of refusing to implement precautionary quotas extends all the way down to a civil society organisation embedded within the RFMO for the Atlantic. 

The world is eating way more fish than it used to. In 1950, the global average per capita consumption of fish was an estimated 6.5kg. Annual per capita consumption in 2023 was about 21.1kg. Over the same period the world’s population grew from about 2.5 billion to eight billion.

The only way this situation is possible is to fish hard. To exploit every resource, in every sea and ocean. An unrelenting assault hurling sharks towards extinction. DM

The research for this article was supported by the Pulitzer Center on Crisis Reporting and Journalism Fund Europe.