The Case of the Blue Shark in the Mediterranean Sea, Episode 1

Image of a blue shark under water
Carijonas
Majorca, Spain
The Case of the Blue Shark in the Mediterranean Sea, Episode 1

In this podcast episode, we embark on a journey to explore the waters of the Mediterranean Sea surrounding the island of Mallorca. Even though we were warned that finding blue sharks might be a challenging task, we were determined to uncover the reasons behind their mysterious decline in recent years.

Despite the data and the feeling that we are talking about a sharp-toothed marine ghost in the Mediterranean, we traveled to Palma de Mallorca at the end of June 2023 to find out how scientists and fishermen manage to keep track of this hatchling species, rarely seen in the last five years on the island. On our expedition, we met people in Mallorca who had done the most work on this species. This was not easy because there are hundreds of them on an island of just over 200 kilometers (km2) with a great biodiversity hub.

These people remain active and proactive in the ongoing developments. A lot of them are actively engaged in the preservation of the island's ecological balance, and their concerted efforts are evident through seamless coordination across a spectrum of environmental projects. We notice the recurrent presence of them in reports, banners, and even press releases, underscoring their duty to the cause. 

So, when three renowned scientists in Mallorca agree, something is indeed wrong. Agusti Torres of the organization SharkMed, told us that despite the relatively high reproduction rate compared to other shark species, the blue shark still faces the risk of extinction, “While we can no longer consider it abundant, it is still holding on, struggling to survive”. Debora Morrison, from the Palma Aquarium Foundation, emphasized that the alarming classification highlights the urgent need for action to protect and conserve these magnificent creatures. And Eric Clua, another expert associated with Shark Med, painted a grim picture of the situation:

Extensive overfishing has decimated shark populations in the Mediterranean, and their numbers have plummeted drastically. 

In recent years, the plight of the Blue Shark in the Mediterranean Sea has been a cause for concern among marine conservationists and scientists. To comprehend the scale of the Blue Shark's decline in the Mediterranean, we turned to a variety of reports and statistics that provide numerical insights into the species' situation. The numbers corroborate the firsthand accounts of scientists, experts, and fishermen we encountered in Mallorca. According to the reports we consulted, populations of the Blue Shark in the Mediterranean have plummeted by an estimated 96 to 99% since the early 19th century. This alarming statistic has been prominently highlighted by the IUCN and its Red List of Threatened Species .

It's important to note that being on the list does not necessarily equate to legal protection. Álex Bartolí, a marine biologist and consultant on fisheries, emphasized that the "critically endangered" designation is not legally binding. He highlighted the challenges of standardizing fisheries management in the Mediterranean due to its socio-economic and political complexities

Blue shark, beyond the bycatch

In this alarming context we got the confirmation that in this expedition it would be almost heroic to see a Blue Shark. However, our friends from Good Karma Projects included us in a planned expedition across the Balearic Sea, around Menorca, Palma, and Ibiza. Their mission included studying plastic pollution, contributing to scientific research, and raising awareness about the sea's environmental condition. Blue sharks were a significant part of their navigation plan, and in collaboration with Shark Med and Save The Med, they diagram a precise trip to visit a device named Shark BRUV (Baited Remote Underwater Video). This device floats in the sea and records blue sharks' behavior as they're attracted by bait.

Agustí Torres, one of the Shark Bruv creators, explained that this device allows for extended monitoring of shark behavior in their habitats. The device uses bait to attract sharks and captures their behavior on camera, providing valuable insights that were previously inaccessible through conventional scientific methods. For example, a significant portion of the Blue Sharks we recorded—almost 50%—showed evidence of being hooked and suffering bycatch consequences. Bycatch, said Agustí, often leads to severe health issues. These hooked sharks carried entangled plants, plastic, nets, and other debris, hampering their ability to chase prey and feed. In milder cases, this was the outcome. In more dire circumstances, these sharks suffered compromised health due to an inability to feed or infections caused by the hooks.

During our exploration in Mallorca, it became evident that the data gathered from this device has evolved into a commonplace of knowledge for the local community. It is as if this remarkable species has transitioned from being just another fish in the Mediterranean, relegated to the status of bycatch, to the real and valued imagery that Agustí Torres generously shares with everyone.

Yet, what truly astonishes us is the amazing existence of this species and its remarkable characteristics. It stands as one of the planet's most iconic migratory species, embarking on journeys that span tropical, subtropical, and warm temperate waters, covering a distance of up to 900 kilometers in just sixteen months. These migratory movements are intricate and cyclical, with tagging efforts conducted between 1960 and 2000 revealing that juveniles, sub-adults, and adults undertake these migrations, often segregated by sex and age.

The patterns of the blue shark's migration are closely tied to its reproductive cycles, and mature individuals traverse international borders, as emphasized in a report by the Convention on Migratory Species. Remarkably, female blue sharks carry their offspring for a gestation period of nine to twelve months and, on average, give birth to 34 pups, a testament to their prolific reproductive capabilities when compared to other shark species.

Fisheries: the most visible face of the blue shark in the Mediterranean

When we asked fishermen in Mallorca with over four decades of experience about the tales of the past involving Blue Sharks and fishermen, they expressed that things are not as they used to be. Their words carry a sense of nostalgia for what is happening with this and other shark species today in Mallorca. Their testimonies are also full of great marine spectacles, which they insist were performed by young, vigorous, and fearless Blue Shark species.

These seasoned Mediterranean fishermen align with research findings. According to data from the Convention on Migratory Species in 2017, between 1998 and 1999, 91% of 3771 studied specimens in this sea were identified as young individuals, largely explaining why this species had little opportunity to reproduce before being captured in fisheries, resulting in a significant decline.

Amongst the many fishermen, there was one individual who notably captured our interest: Pedro Mercant, a seasoned fisherman boasting 35 years of experience and currently serving as the president of OP Mallorca Mar. Our discussion revolved around the intricate issue of bycatch and the fishermen's perspective on the decline of blue sharks in the Mediterranean. Pedro unequivocally confirmed that past practices within the fishing industry had indeed been flawed. He emphasized that Blue Sharks have never been the intended target of fishing endeavors in Mallorca. He further expounded on the situation by highlighting the blue shark's distinct characteristics, which make it highly susceptible to incidental captures. According to Pedro, the Blue Shark is an aggressive, agile, and voracious species, which renders it more prone to being inadvertently caught.

Pedro underscored that this inherent behavior of the blue shark inadvertently contributes to its capture during routine fishing operations. It is this unfortunate collateral damage, as Pedro remarked, that has led to the classification of the blue shark as a threatened species in the Mediterranean.

As the chessboard of the Mediterranean's Blue Shark scenario becomes more complete, there remains a crucial need to gain a deeper understanding. This is a complex management equation that includes marine protection conventions, regional fisheries management organizations, such as the International Commission for the Conservation of Atlantic Tunas (ICCAT), rules, and regulations, not forgetting the omnipresent fishing interests. 

A deeper perspective on this issue, which we delve into extensively in our second podcast episode, reveals that Spain is responsible for a significant 25% of worldwide blue shark catches. Additionally, Spain holds the distinction of being the top importer of blue shark meat, as reported by OCEANA .

Our journey led us to the Shark BRUV, where we hoped to deploy bait and observe blue sharks in their natural habitat. Although we did not see any Blue Sharks on this Good Karma Projects expedition, we found several of them elsewhere. Despite the challenges, we were determined to uncover the truth about what is happening to blue sharks in the Mediterranean, are they the victims of bycatch or are they being deliberately targeted? What is the interaction between blue shark bycatch and swordfish catches? Finally, we ask you one question to answer at the end of the series, who is the predator and who is the prey? Therefore, there are several topics that still need to be revealed in our next podcast episode.

Join us as we continue our journey to uncover the mysteries of the blue shark in the Mediterranean.

Listen to the first episode in English (translated using AI): 

And in Spanish:

 


This story was produced with support from Internews' Earth Journalism Network. It was first broadcast in Carijonas on 26 November 2023 in Spanish; this version has been adapted by EJN's Mediterranean Media Initiative.

Banner image: Blue shark (Prionace glauca) off southern California / Credit: Mark Conlin for NMFS via WikiCommons.

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