In July 2023, an unprecedented event occurred in the northeastern Atlantic: the first documented attempt at mating between two blue sharks (Prionace glauca) in open waters off Bermeo.

The sequence was recorded during a MAKO PAKO expedition and later analyzed in a scientific study published in Web Ecology (2025). This event, together with data collected since 2021, reinforces the hypothesis that the Basque coast may function as a reproductive activity area for this pelagic species.

On July 31, 2023, along the slope of the submarine canyon off Bermeo, a complete sequence of precopulatory behavior was recorded:

Parallel swimming of the male alongside the female

Persistent following

Courtship bite to the pectoral fin

Simultaneous inversion of both sharks

Attempt by the male to maintain the grip

Sudden escape by the female

The interaction lasted just over four minutes. Copulation did not occur, but the behavioral pattern matches exactly what has been described in other elasmobranch species during mating events.

Although the observed female had not yet reached sexual maturity, this does not invalidate the interpretation. In other regions of the Atlantic, courtship bites have been documented in juvenile females. Males tend to maximize reproductive opportunities, and females are capable of storing sperm until reaching maturity. Therefore, the behavior recorded fits well within the known reproductive repertoire of the blue shark.

If this area is confirmed as a reproductive zone, the implications are significant:

• Greater ecological value than previously assumed
• Need for targeted studies and specific sampling
• Direct relevance for fisheries management
• International importance for blue shark conservation

In this region, juveniles, adult females, and adult males coincide during the reproductive season—an exceptional pattern for a species with such a wide oceanic distribution.

All these observations originate from shark snorkeling activities carried out by MAKO PAKO since 2020. This demonstrates a fundamental point: when structured rigorously, responsible ecotourism can generate scientific data that would otherwise not exist.

In the Cantabrian Sea, there are virtually no observation programs independent of fishing activities.
Documenting wildlife provides new and valuable information for this region.

This observation, together with the accumulated evidence, points toward an emerging reality: the Basque coast may be a key area in the reproductive cycle of the blue shark.

For MAKO PAKO, being at the forefront of these observations reinforces the importance of:

• Continuing to develop ethical, science-based ecotourism
• Collaborating with researchers
• Providing useful data to the scientific community
• Protecting a habitat that is far more than a transit area

The Cantabrian Sea is beginning to reveal its role in the biology of this species, and this record represents a decisive step toward understanding it.

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In 2025, the IUCN Shark Specialist Group identified the Basque Coast as an Area of Interest (AoI) within the international ISRA (Important Shark and Ray Areas) process.

This recognition does not designate the area as a protected site, but it does highlight it as a region with high ecological potential for sharks and rays—particularly for the porbeagle shark (Lamna nasus), which is currently classified as Vulnerable at a global level.

For those of us working in the Cantabrian Sea, this step is not simply relevant; it is a key piece in better understanding and protecting the pelagic species that inhabit our coastline.

AoIs are part of the scientific assessment process that precedes ISRA designation.

They are areas where:

• There is existing scientific evidence, although still incomplete
• One or more criteria relevant to sharks and rays may be met (reproduction, feeding, regular use, etc.)
• Further research and data collection are required

The IUCN assessment focuses on the porbeagle shark (Lamna nasus), one of the most emblematic yet least understood species in the European Atlantic. Between 2020 and 2024, 11 juvenile and neonatal individuals were recorded in the area, indicating that they were newly born sharks.

These data suggest something of major significance: the Basque Coast could be a potential nursery or reproductive area for the porbeagle shark. If confirmed, this would place the region among the very few locations worldwide identified as fulfilling this role for the species—granting it critical importance.

The porbeagle shark is notoriously difficult to study. It is a pelagic species, ranges across oceanic waters, is observed only sporadically, and neonates are extremely rare to document. The presence of neonatal records along the Basque Coast is therefore exceptional and may redefine our understanding of how this species uses the Cantabrian Sea.

However, confirming this hypothesis will require more data and continued observation.

For us, this recognition further confirms what we observe on a daily basis: the Cantabrian Sea is a unique ecosystem. Our role remains unchanged:

• Observe responsibly
• Document with scientific rigor
• Contribute useful data to the scientific community
• Share the ocean ethically with those who join us at sea

The declaration of an Area of Interest is a major step forward—not because it creates a new protection status, but because it places the Basque Coast on the global map of shark conservation.

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The coast of Bermeo has been identified as an Important Shark and Ray Area (ISRA) by the IUCN Shark Specialist Group.
This recognition places the Cantabrian blue shark on the international map as a species with critical areas for reproduction and pelagic habitat use.

What makes this ISRA particularly significant is that part of the evidence used comes directly from observations made during MAKO PAKO’s shark snorkeling expeditions. It is a scientific milestone, but also a shared one: researchers, responsible operators, and hundreds of people who have taken part in these expeditions have all contributed to it.

ISRAs are not administrative figures or protected areas.
They are zones identified through strict scientific criteria as essential for sharks and rays, particularly due to key functions such as:

• Reproduction
• Feeding
• Recurrent presence
• Critical habitat use

In the case of Bermeo, the area meets Criterion C1 — Blue shark reproductive area (Prionace glauca). Officially identifying such an area provides a solid scientific basis for future management measures and helps protect habitats that were previously invisible to both science and policy.

Fisheries and oceanographic data had long suggested that the Bermeo coast was a relevant area. However, demonstrating actual reproductive use required continuous, direct surface observations: neonates, juveniles, females with mating scars, and even courtship behavior.

This cannot be achieved by a scientific vessel operating once a year. It requires constant presence, season after season.

Between 2020 and 2024, our blue shark snorkeling expeditions—from June to October each season—generated a unique, consistent dataset of high scientific value.

This is what you helped make possible:

Biological and Behavioral Data

• Five years of systematic blue shark observations
• Documentation of juveniles and subadults early in the season
• Seventeen females with mating scars
• One mating attempt recorded in 2023
• Active feeding behavior on anchovy schools

Presence and Aggregation Data

• Groups of 3 to 15 individuals observed regularly
• Repeated seasonal trends across multiple years
• Interannual variations that help explain migratory patterns

Visual Data

• Photographs and videos used to verify size, scars, and behavior
• Reference material included in reports, projects, and scientific conferences
• Without this continuity, many of these data would simply not exist.

What makes this project unique is that it is not science disconnected from the public—it is citizen science in its most effective form. Every participant, every photograph, every observation shared from the water adds value.

You helped to:

• Record the number of individuals per outing
• Estimate sizes and life stages
• Document scars, markings, and unique individuals
• Compare seasons
• Verify behaviors

This collective work has been integrated into:

• Observadores del Mar projects
• Scientific reports
• Oceanographic analyses
• ISRA assessment criteria

Without your participation, this database would not exist.
And without that database, the Bermeo ISRA would have been far more difficult to demonstrate.

Shark tourism often sparks debate. In this case, the opposite is true. Shark snorkeling in the Cantabrian Sea—carried out under ethical protocols and with a scientific approach—has generated information that no research vessel could have collected with such frequency and continuity. It is a clear example that, when done properly, responsible tourism can generate real science and contribute directly to conservation.

The ISRA designation does not imply immediate protection, but it does mark a turning point:

• The scientific community recognizes Bermeo as a critical area for pelagic sharks
• Authorities now have solid arguments to establish conservation measures
• The data collected will continue to be valuable for future studies
• The Cantabrian Sea enters the international radar as a key region for blue sharks

The Bermeo ISRA is not just a scientific success. It is proof that when work is carried out with rigor, consistency, and ethics, a simple day at sea can become a genuine contribution to conservation. This recognition exists thanks to researchers, everyone who has taken part in our expeditions, and MAKO PAKO. Your support, trust, curiosity, questions, photographs, and involvement have made it possible for the Basque pelagic ecosystem to receive international recognition.

If you would like to learn more about our work or contribute to future observations, you can join our expeditions or take part in citizen science projects in the Cantabrian Sea.

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