Broad Stingray

The broad stingray (Bathytoshia lata), also known as the brown stingray or Hawaiian stingray, is a member of the Dasyatidae family and is predominant in the inshore waters of the Hawaiian Islands. Its habitat extends across the Indo-Pacific, from southern Africa to Hawaii (🇺🇸 United States), and it also inhabits the Eastern Atlantic, from southern France to Angola, including the Mediterranean Sea. Typically residing on sandy or muddy flats at depths exceeding 15 meters (49 feet), this benthic species predominantly reaches up to 1 meter (3 feet) in disc width. The broad stingray is characterized by a wide, diamond-shaped pectoral fin disc with a protruding snout and a lengthy tail accompanied by a ventral fin fold. Nocturnally, it actively searches for benthic invertebrates and bony fishes, frequently near reef boundaries. Reproductive activity in this species is aplacental viviparous. Due to significant threats across its broad range, the International Union for Conservation of Nature (IUCN) has classified this species as Vulnerable.

The broad stingray was first described by American zoologist Samuel Garman in 1880 in the scientific journal Bulletin of the Museum of Comparative Zoology, originally under the name Trygon lata. Later taxonomic revisions placed it within the genus Dasyatis. The type specimen, collected from the former "Sandwich Islands," measures 52 centimeters (20 inches) across.

In its geographical distribution, Bathytoshia lata is found across the eastern Atlantic and the Indo-Pacific, ranging from southern Africa to the Hawaiian Islands, with occasional records in the Mediterranean, from Spain to 🇹🇷 Turkey. This species is commonly associated with coastal bays characterized by muddy or silty substrates and may also be encountered in sandy regions or near coral reefs. Typically, it is found at depths ranging from 40 to 200 meters (130–660 feet), extending down to 800 meters (2,600 feet).

Morphologically, the broad stingray features a diamond-shaped pectoral fin disc that is about one-fourth wider than long, with straight leading margins meeting at an obtuse angle and curved trailing edges. Its snout is rounded and extends past the disc. The mouth is arched, containing five or six oral papillae, two of which are positioned anteriorly. The whip-like tail, often twice or more the length of the disc, includes a serrated stinging spine and a ventral fin fold that gradually transitions into a keel towards the tail's tip. Larger individuals display three large, elongated tubercles along the back, and the tail is textured with dermal denticles and an irregular row of conical tubercles along the sides. Dorsally, the broad stingray presents an olive to brown coloration, contrasting with its white ventral surface. While similar to the diamond stingray (Hypanus dipterurus), which occasionally inhabits Hawaiian waters, the broad stingray can be distinguished by a longer tail with only an upper fin fold. The broad stingray can attain a width of 1.5 meters (5 feet) and a weight of 56 kilograms (123 pounds), although most do not exceed 1 meter in width.

Behaviorally, the broad stingray exhibits low activity levels during daylight, often remaining semi-concealed beneath the substrate. A tracking study conducted in Kaneohe Bay reported average nightly roaming over an area of 0.83 square kilometers (0.32 square miles), in contrast to a diurnal range of 0.12 square kilometers (0.046 square miles), with activity peaking two hours post-sunset and pre-sunrise. Activity correlates positively with elevated summer water temperatures, remaining largely unaffected by tidal changes due to the deeper habitats.

Dietarily, the broad stingray primarily consumes benthic crustaceans, along with polychaete worms and small bony fishes. It employs excavation to uncover concealed prey and is often shadowed by opportunistic species such as jacks. Foraging sites are typically near reef peripheries, where numerous undefined, wrasses, gobies, and other reef-dwelling fishes seek nocturnal refuge. Known parasitic infections in this species include tapeworms such as Acanthobothrium chengi, Rhinebothrium hawaiiensis, Pterobothrium hawaiiensis, Prochristianella micracantha, and Parachristianella monomegacantha. Reproductively, the broad stingray is aplacental viviparous, with Kaneohe Bay acting as a critical nursery habitat, where it shares space with juvenile scalloped hammerheads (Sphyrna lewini) as principal predators. Observations off North African coasts suggest birthing occurs in June and December, indicating either biannual litters with a four-month gestation, or separate female cohorts birthing annually with a ten-month gestation period.

When encountering divers, the broad stingray exhibits a shy demeanor but remains approachable, generally retreating if approached too closely.