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 Text and photos copyright John P. Hoover

past fishes of the month


Dasyatis lata (Garman, 1880)


(Brown Stingray)
Dasyatis lata (Garman, 1880)
      This is Hawaii's most common stingray. Its roughly diamond-shaped body has convex borders and is slightly wider than it is long. When viewed from above, its front tip is distinctly pointed. The tail is twice the length of the body and a fold or keel of skin runs along its underside. The wide portion of the tail is studded with spiny tubercles. As in all stingrays, a venomous spine sits atop the tail just behind the body. The species is said to attain at least 5 ft. in width, although 3 ft. is more usual. It is known only from Hawai`i and Taiwan.
Finding a stingray is unusual in Hawai`i. These bottom-dwellers are most common in muddy or silty embayments such as Maui's Ma`alaea Bay and O`ahu's Kane`ohe Bay, where divers and snorkelers seldom go. They will also live over sand, however, and divers occasionally encounter them foraging adjacent to reefs or lying half-buried. Depths are typically about 50 ft. or more, although I once saw one in 8 ft.
      Although you may never see a stingray, you can tell if you're in stingray country by the presence large craters and pits in the sand, created by rays as they excavate for buried prey--perhaps sand-dwelling fish, worms, crustaceans, molluscs, or echinoderms. To see a large active ray churning up great clouds of sand must be quite a sight. A jack often follows a foraging ray, possibly to nab small escaping animals or perhaps just to get scraps.

Tracking stingrays
     Little is known about the biology or ecology of stingrays in Hawai`i--or anywhere for that matter. Researchers in Kane`ohe Bay, O`ahu, recently caught a number of Broad Stingrays with hook and line, tagged them with acoustic transmitters, and let them go. By following individual rays with small boats for periods of up to 74 hours, they discovered that the rays range widely at night, are less active by day, and do not return to predictable areas to rest. It would seem from this that the rays forage mostly at night. If this is so, it might also follow that prey animals are more abundant near reefs because 30 percent of the positional fixes were within 60 ft. of the edge of a reef. Known available prey from the muddy bottom of Kane`ohe Bay consists primarily of small burrowing polychaete worms, gobies, shrimps, crabs, and possibly reef fish that bury themselves at night.
     The photos on this page were all taken at Pupukea, O`ahu, at a depth of 70 ft. at a specific location where I have seen rays off and on for over 10 years. The pictured ray was about 3 ft. wide. The jack is a small Bluefin Trevally (Caranx melampygus). In recent years large stingrays have become popular exhibit animals in Island aquariums and resorts. The scientific species name is Latin for "broad."

Other Hawaiian stingray species
    In addition to the species above, the Diamond Stingray (Dasyatis dipterura) has also been recorded from Hawaiian nearshore waters. (The scientific name is listed as D. hawaiiensis or D. brevis in older books and the common name Hawaiian Stingray is also used.) This species, normally a resident of the Eastern Pacific, is rarely seen in Hawai`i.
     How to tell the two apart? The Diamond Stingray is about the same size and color as the Broad Stingray but it has two folds or keels of skin running down its tail, one on the upper and one on the lower side. (The Broad Stingray has a single fold on the underside.) In addition, the Diamond Stingray's tail is only about 1.5 times the length of the disc, whereas the Broad Stingray's tail is about twice the length of the disc. If you see a Diamond Stingray, I'd like to hear the details. Try to confirm the ID with a photo of the tail.
     The Violet Stingray (Dasyatis violacea), a pelagic species which lives in the open ocean far from land, is present offshore in Hawaiian waters.

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  Text and photos copyright John P. Hoover