Juvenile Great White Shark Confirmed in Spanish Mediterranean Waters

The specimen, measuring about 210 centimeters and weighing between 80 and 90 kilograms, was captured on 20 April 2023 at coordinates 38°42.089'N, 000°20.325'E within the Spanish Exclusive Economic Zone. Because confirmed recent records of white sharks in the Mediterranean are so scarce, any new verified occurrence carries considerable scientific and conservation significance. Species identification was not left to eyeball judgment alone.

Polymerase chain reactions were run in 25 microliter volumes with carefully specified primer, dNTP, magnesium chloride, and polymerase concentrations, beginning with five minutes of denaturation at 94°C followed by 35 cycles alternating 94°C, a 44°C annealing step, and 72°C extension, then a final seven-minute extension. Products were visualized on a 1% agarose gel, purified, and sequenced in both directions. When the resulting sequences were assembled, edited, and compared against the GenBank database using BLAST, the match to white shark was decisive: 98% query coverage, an E value of 0.0, and 98% percent identity, with the sequence deposited under GenBank accession number PV998081.

Records of newborn and juvenile white sharks are conspicuously scarce throughout the Mediterranean. The Strait of Sicily and the Gulf of Gabès have long been considered the main breeding grounds for the species in the basin, but eleven newborns documented since 2008 have led scientists to propose the Bay of Edremit in the northeastern Aegean Sea, in Turkish waters, as a possible second nursery ground and an emerging hotspot for Mediterranean white sharks. The presence of a juvenile off Spain therefore raises a question the authors cannot yet answer: was this animal born in the central Mediterranean nursery and migrated westward, or was it born off the Spanish coast itself?

The white shark is one of the most iconic members of the oceanic megafauna, capable of reaching lengths of up to 640 or even 660 centimeters. As a top predator in both coastal and pelagic environments, it plays a crucial role in maintaining trophic balance by controlling prey populations, with cascading effects that reach down to coastal seagrass and kelp ecosystems, influencing habitat quality and even carbon sequestration. Yet the species has suffered a pronounced global decline.

The International Union for Conservation of Nature currently classifies it as Vulnerable, based on an estimated population reduction of 30% to 49% over the past three generations, a span equivalent to roughly 159 years. The shark's biology makes recovery slow: it can live up to 73 years, matures at a threshold of about 4.5 meters, a length that encompasses most adult females and mature males, and has a generation length of about 53 years. In the Mediterranean, the white shark's presence has long been inferred mainly from sporadic sightings, incidental bycatch, and historical records rather than systematic monitoring.

A comprehensive review by Boldrocchi and colleagues in 2017 compiled and assessed available data on the species' historical and current distribution in the region, documenting 62 occurrences in Spanish waters. Of these, nine cases dated between 1986 and 2001 were considered indirect evidence, based primarily on bite marks observed on stranded marine animals, especially sea turtles. Focused assessments have also identified specific areas of occurrence, such as the waters surrounding the Balearic Islands, an ecologically sensitive region within the western Mediterranean basin.

Those Balearic waters tell a grim quantitative story. A recent study by Moro and colleagues demonstrated a significant decrease in white shark abundance in the peripheral sectors of the Mediterranean, finding that between 1980 and 2016 the population of Carcharodon carcharias in Balearic waters declined by more than 73%. Against that backdrop, the confirmed capture of a juvenile in a marine region where the species has been documented to have drastically collapsed is of remarkable conservation significance.

It suggests the species has not been fully extirpated from the western basin, even if it survives there only as a ghost of its former abundance. A fatal shark attack on 27 July 1862 near Málaga was reported in the newspaper El Avisador Malagueño, in a piece authored by Francisco López in its Gacetillas section. The report detailed a fatal attack on a bather at San Andrés beach, west of Málaga city, describing the shark severing the victim's leg at the thigh and referring to the attacker as a large marrajo.

While that Spanish vernacular term is commonly used today for various large sharks, interviews with professional fishers indicate that 63.91% use it specifically to refer to the white shark, lending the 1862 account plausible weight as a historical record not compiled in the 2017 review. Indirect evidence has continued into the modern era. On 2 April 2006, a recreational fisher observed a loggerhead turtle at sea bearing severe injuries: the 90-centimeter, 32-kilogram animal showed a deep semicircular wound measuring 30 by 30 centimeters on its plastron with visible tooth marks, along with partial amputation of a front flipper.

These injuries likely resulted from predation by a large shark such as a white shark, and the bite patterns and wound morphology are consistent with lamnid sharks, although definitive identification remains elusive without genetic material or direct observation. Such records remain ecologically meaningful because they imply the presence of large predators in the system. Earlier work by Fergusson and colleagues, based on stomach content examinations, described four records of marine turtles eaten by white sharks in the Mediterranean, confirming from carapace remnants that both loggerhead and green turtles were preyed upon in those waters.

More recently, on 12 June 2015, a press article reported the accidental capture of a large white shark exceeding 5 meters near Bolonia Beach in Tarifa, at the Strait of Gibraltar, during tuna fishing operations, with photographic evidence confirming the species' identity. Why would white sharks, rare as they are, keep appearing off Spain? The authors point to a well-documented prey–predator relationship: the seasonal migration of Atlantic bluefin tuna into the Mediterranean for spawning.

The 2023 juvenile capture, combined with earlier documented occurrences of both adult males and females mainly during spring and summer, suggests that Spanish waters may function as a transient corridor tied to the movements of this prized prey. The correlation has precedent elsewhere in the basin. The drastic decline and subsequent absence of bluefin tuna in Marmaric and Bosphoric waters, the northernmost extension of the Mediterranean ecosystem, exhibits remarkable synchrony with the decline and absence of great white sharks there, a region that also recorded the species' greatest documented population decline at 96.6%.

According to recent assessments, spatial changes in white shark occurrence patterns in the Mediterranean closely align with shifts in tuna feeding grounds and cooler sea surface temperatures below 18°C. The proximity of these sightings and captures to ecologically significant areas such as the Balearic Islands underscores the conservation stakes. Previous studies have recognized that region as potentially significant habitat or a migratory corridor for the species, and the addition of new verifiable records reinforces calls for its consideration as a priority area in regional conservation planning.

Comparable findings elsewhere in the western Mediterranean support this picture: following recent observations of bite marks on a large female white shark, researchers proposed an area off the coast of the Parc Naturel Régional de Camargue in the French Mediterranean as a key late-summer feeding area for female white sharks after copulation. Given the species' Vulnerable status, the authors argue that continued monitoring is critical, and they call for systematic, long-term observation programs combining direct methods such as visual sightings and capture data with indirect tools such as environmental DNA analysis and satellite telemetry. Such efforts, they contend, are essential for improving understanding of white shark biology in the Mediterranean and for informing evidence-based strategies to protect and recover this iconic apex predator.

Subject of Research: A genetically confirmed new record of a juvenile white shark from the Spanish Mediterranean coast and its implications for the species' presence and conservation in the region.

Article Title: New record of white shark, Carcharodon carcharias ( Elasmobranchii , Lamniformes , Lamnidae ), from the Mediterranean Spanish coast

Article References: Báez, J. C., Puerto, M. A., Torreblanca, D., Varela, J. L., Carmona, L., & Macías, D. (2026). New record of white shark, Carcharodon carcharias (Elasmobranchii, Lamniformes, Lamnidae), from the Mediterranean Spanish coast. Acta Ichthyologica et Piscatoria, 56, 27-31. https://doi.org/10.3897/aiep.56.173786

Image Credits: AI Generated

DOI: 10.3897/aiep.56.173786

Keywords: white shark, Carcharodon carcharias, Mediterranean Sea, Spain, genetics, COI barcode, bluefin tuna, conservation, IUCN Vulnerable, Balearic Islands, nursery grounds, apex predator