Spotted Eagle Ray (Aetobatus narinari)

 

 

The above video, "Spectacular when spotted",  was filmed for the PhD project of Matthew Ajemian. Matthew is in the final year of his project at the University of South Alabama with Dr. Sean Powers. The aim of the project is to better understand the movements and diets of the Spotted Eagle Ray (Aetobatus narinari). A variety of techniques were utilized to meet this goal, eagle rays were fitted with both acoustic and satellite transmitters to track both large and small-scale movements. Gastric lavage was used to determine preferred prey items, and enclosure experiments were used to observe the animals and determine prey patch selection. All the work done to understand these animals has led to their protection in Bermudian waters.

 

About the Spotted Eagle Ray

The Spotted Eagle Ray is the only ray commonly seen in Bermuda. Locally, this species is often referred to as the “Whip Moray”. Eagle Rays are native to Bermuda and appear to be resident year-round. In the Western Atlantic they are found from Virginia south to Brazil, and throughout the Caribbean and Gulf of Mexico 1. In Bermuda they can be seen cruising over sandy bottoms in inshore bays and on the reef platform in sandy areas. However, eagle rays also traverse deeper regions of Harrington Sound, often exceeding 20 meters in depth, and have been observed by divers at offshore seamounts. Eagle Rays are most often seen passing in and out of Harrington Sound under Flatts Bridge.

Unlike their stingray relatives, Eagle Rays have a pronounced head with a snout, and eyes on the side of the head. These rays are beautifully marked, with a black, dark brown or dark grey back, covered by characteristic white spots and rings, and a bare white underside. These markings along the dorsum are individually specific and can be used as natural “tags” by scientists. Eagle Rays have a long thin tail with up to 7 barbed spines at the base. Wingspan in Bermudian rays generally ranges from 1.2 m (4 feet) to a maximum of about 2 m (6.5 feet).

Feeding rays often leave craters in the sand as they submerse their large heads and excavate buried prey. They dig up molluscs like Calico and Ark Clams and larger individuals will even occasionally crack through a Conch. The mouth is located on the underside of the head. Eagle Rays do not have typical teeth; instead they have hardened dental plates in the upper and lower jaws, which they use for grinding and crushing mollusc shells.

Occasionally Eagle Rays can be seen jumping out of the water. The reason they do this remains a mystery. Scientists speculate that leaping rays may be females trying to avoid unwanted male attention, or they may do it to shake off parasites or remoras. They may also perform these noisy belly-flops just for fun.

Spotted Eagle Rays give birth to live young which look like miniature copies of the parents. The baby rays are called ‘pups’ and about 4 are born in each litter.

Eagle Rays are difficult to approach in the water as they tend to swim rapidly away from divers and swimmers. Eagle Rays are not dangerous to humans unless they are caught and handled incorrectly.

 

Spotted Eagle Rays appear on the IUCN Red List of Threatened Species as ‘Near Threatened’ due to fishing throughout the world 1. The Bermudian population of this species is considered slightly more endangered and is classified as 'Vulnerable VU (A2d)' according to the IUCN Red List criteria.

Bermuda’s Spotted Eagle Rays are at risk from exploitation of any kind because the local population is believed to be relatively small and individuals of this species produce only 4 or fewer young each year. For these reasons removing even a few Rays from the population by fishing can have a serious impact on numbers very quickly. Due to recent targeting of this species for consumption, local conservation measures were needed urgently. 

On September 30th 2010 the Spotted Eagle Ray was listed under the Bermuda Protected Species Act 2003 (see Protected Species Amendment Order 2010). The Eagle Ray was listed as a Level 1 protected species in 2012. Anyone convicted of catching and/or killing an Eagle Ray will be fined $25,000 or imprisoned for 2 years.  

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Eagle Ray protection legislation in Bermuda from LookBermuda on Vimeo.

Bermuda's Eagle Ray protection legislation.