Stingray Bahamas | ROLLING HARBOUR ABACO

RAYS OF SUNSHINE ON THE ABACO MARLS

The Marls of Abaco are prime bonefishing grounds, a vast area of labyrinthine mangrove swamps, sandy islets, channels and shallow flats on the west side of the main island. The fish are wily and powerful, the fly hooks are barbless, and each one caught, retained, boated and swiftly released is a prize. There’s plenty of other wildlife to be seen. Heron and egrets, ospreys, belted kingfishers, wading birds and many other bird species make the Marls their home. In the water, there are snappers, jacks, barracuda, and sharks of various kinds and sizes. These latter range from small black tip, lemon and hammerhead sharks to more substantial contenders, with the occasional massive bull shark to add a frisson for those on a suddenly fragile-seeming skiff…

There are also rays. I have posted before about the SOUTHERN STINGRAY and the YELLOW STINGRAY. Out on the Marls I have mainly seen Southerns as they move serenely and unhurriedly through the warm shallow water. A couple of weeks ago, we were out with the rods when we had a completely new Ray experience. I’m not overly given to anthropomorphism and getting too emotional about encounters, but we all found this one quite moving – even our very experienced guide.

Gliding to our right side, a pair of stingrays slowed as they neared the skiff

The adult paused very close to us, allowing the little ray to catch up

Lifting a wing slightly the adult let the juvenile creep under, while keeping a beady eye on us

The large ray was missing the tip of its tail, presumably from some adverse encounter

The creatures examined us carefully for 2 or 3 minutes, before separating

Then they slowly drifted away across the sand…

According to our guide, this gently protective behaviour is not uncommon. They may well have been completely unrelated, the large ray tolerating the smaller one accompanying it through the waters and offering a kindly wing in the presence of danger or suspicious objects like us.

Photo Credits: Mrs RH (I was too entranced at the sharp end, with a bird’s eye view, to get a camera out)

BAHAMAS REEF FISH (4) – YELLOW STINGRAY Uboritas jamaicensis

The YELLOW STINGRAY (Uboratis jamaicensis) is one of several ray species found in the tropical western Atlantic ocean. They live in shallow water on sandy or seagrass bottoms, and are commonly found near coral reefs. Their light and dark splotchy colouring can rapidly change according to the surroundings and the need for camouflage. Look at the photos below with half-closed eyes and (apart from knowing perfectly well that there’s a ray there), the blending in is remarkable.

The yellow stingray feeds on small invertebrates and fishes. It can use its ‘wings’ to uncover buried / hiding prey by disturbing the sand. It also has a subtle ‘passive’ method of hunting by using its mantle to form a lethal ‘cave’ that attracts shelter- or shade-seeking prey.

Yellow stingrays breed in seagrass. They are quite prolific, breeding year round and usually having two litters a year of up to 7 young. This species is ‘aplacental viviparous’: the developing embryos are sustained initially by yolk and later by uterine milk. To find out more about viviparity, you’ll find a section at the bottom of this post where the inquiring may opt in… Not everyone’s sac of yolk, I quite understand.

The yellow stingray is innocuous towards humans, but can inflict a painful injury with its venomous tail spine. The threats to the species are (1) taking as bycatch by commercial fisheries; (2) collection for the aquarium trade; (3) negative impact from habitat degradation, both of reef areas and seagrass breeding grounds. For now, it remains common and widespread and retains its IUCN LISTING of ‘Least Concern’.

REPRODUCTIVE STRATEGIES (Marine Biodiversity, Canada)

As with all elasmobranchs, skate and rays are internal fertilizers. Internal fertilization is beneficial because it increases the likelihood and efficiency of fertilization by reducing sperm wastage. In addition, it ensures that the energy-rich eggs produced by the female are not consumed by predators, and that all the energy allocated to reproduction is passed to the embryos and not lost to the environment. This is especially the case for species that retain their embryos until the embryos have completely developed, a reproductive mode termed viviparity. Elasmobranches that practice viviparity are called viviparous (or live-bearing). There are many types of viviparity, which can be divided into two broad categories: aplacental and placental viviparity. Placental viviparity is the most advanced mode of reproduction, during which the embryos are initially dependent on stored yolk but are later nourished directly by the mother through a placental connection. This type of reproduction is not exhibited by any type of batoid. Ovoviviparity (or aplacental viviparity), on the other hand, is the only mode of reproduction employed by rays. In rays, the embryos rely on the substantial yolk within the ovulated egg only during the initial stages of development. After the nutrients stored in the egg have been consumed, the embryo ingests or absorbs an organically rich histotroph (or “uterine milk”) produced by the mother and secreted into uterus. The most highly developed of these strategies occurs in some rays in which the lining of the uterus forms tiny, finger-like projections (termed trophonemata) that increase the surface area for histotroph secretion. This form of nutrient supply (or maternal investment) results in very large offspring, which is characteristic of most species of ray.

For those now fluent in viviparity, the treat of one of Melinda Riger’s fabulous aquatic close-up photos – keeping a close eye on you…Credits: Melinda Riger of Grand Bahama Scuba, with thanks; Wiki for other images / source material; selected online pickings