The finding is part of a larger two-year survey led by Roxanne Cabebe-Barnuevo of the University of the Philippines Visayas, focusing on cartilaginous fish in regional markets. The study, published in Acta Ichthyologica et Piscatoria, not only sheds light on the undocumented presence of sandbar sharks in the area but also reveals the vulnerability of species typically absent from scientific records.
Sandbar sharks are commonly found in fisheries worldwide, but their slow growth and low reproduction rates make them highly susceptible to overfishing. That vulnerability becomes even more pressing when newborn individuals start showing up regularly in local fish markets, especially in regions where monitoring and regulations are limited.
Distinct Field Traits Confirmed the Species’ Identity
When the fishermen delivered the shark to a local port, it immediately caught the attention of a visiting research team. The shark’s prominent physical features — including disproportionately large eyes, a tall first dorsal fin, and dusky-edged fins — matched well-known descriptors of the sandbar shark, a species that had never been confirmed in the Philippines before.
According to Earth, three male specimens were measured between 35 and 38 centimeters in length. These are sizes smaller than what is documented as the species’ birth length, which signals the presence of neonates and raises red flags about possible nursery grounds being disturbed by local fishing.
The research team ensured verification through both morphological analysis and DNA barcoding. Classical anatomical measurements were paired with a mitochondrial COI gene sequence to match reference samples. The method allowed for high-confidence identification, supported further by photographic documentation and cataloged voucher specimens stored at the University of the Philippines Visayas Museum of Natural Sciences.
Local Fisheries Unintentionally Expose Hidden Biodiversity
The survey covered fish landings in Panay and Guimaras over a two-year span, focusing exclusively on sharks, rays, skates, and chimaeras. A total of 14 species were documented: six sharks, seven rays, and one chimaera. Researchers purchased each specimen directly from local markets and ports for lab analysis.
Among the findings were two batoid species that did not match any existing descriptions, suggesting the potential presence of undescribed species in coastal waters that are fished routinely. According to the same source, the survey also recorded ghost sharks and spottail sharks, along with rays and catsharks, offering a rare window into species that typically bypass academic or conservation-focused documentation.
The practice of market-based monitoring is increasingly seen as a practical method to understand what is being caught and from which habitats. It provides timely data on vulnerable marine species that are otherwise difficult to monitor in the wild, especially in small-scale fisheries where formal reporting is minimal.
Life History Traits Put Sandbar Sharks at Risk
The Carcharhinus plumbeus is currently listed as Endangered by the IUCN. It has a slow reproductive cycle — with long gestation, late maturity, and small litters — and a generation length estimated at 20 to 26 years. These factors make population recovery slow, especially when exposed to frequent captures in nearshore environments.
As noted in the Florida Museum’s species profile, sandbar sharks are often targeted because of their moderate size, palatable meat, and high fin-to-carcass ratio. This economic appeal has led to the species becoming a primary catch in some areas, raising concerns about its long-term sustainability.
The presence of very young individuals in the Philippines — a location where the species was not even recognized until now — suggests that the country’s coastal habitats may play a role in its life cycle. Tracking such occurrences can inform local conservation actions, such as the regulation of gear types or protection of nursery areas in shallow bays.