Monday, December 21, 2020

The Electric Torpedo Ray of New England

The Shocking Ray of New England

Blog by Coleman Earner - December 21, 2020

Dead Torpedo Ray in Brewster, MA

Torpedo Rays are a genus of rays that are part of the Order Torpediniformes (electric rays). In reference to local sightings, the most commonly seen torpedo ray in the Cape Cod region is the Atlantic Torpedo (Torpedo nobiliana). They are cartilaginous fish (most similar to the structure of sharks and skates) with a flat and rounded disc-like structure. As suggested by their order, torpedo rays are most commonly known for their ability to discharge electricity of up to 220 volts from both pectoral fins (pectoral fins are flat and expanded and fused to the head area) as a self defense mechanism or as a means of capturing prey. Their feeding strategy consists of burying themselves under the sand and waiting for unsuspecting prey to wander by. 


Dead Torpedo Ray on a
Cape Cod Beach.

Torpedo Rays feed mainly on benthic/pelagic fish such as flounders, damselfish, and other small fish during the night. Depending on their size, a fully grown Atlantic Torpedo Ray may prey upon much larger fish such as small sharks, eels, and larger mullet fish. Atlantic Torpedo Rays are typically observed to grow 2-5 feet in length, but have been observed to grow as large is 70.9 inches. It is due to this large size and electrical discharge that larger predators rarely seek out Torpedo Rays for prey. In regards to their distribution, Atlantic Torpedo rays are found mainly on Atlantic coastlines ranging from Canada to Brazil as well as Scotland to Morocco in eastern regions. 
 

The identification of Torpedo Rays are crucial to ensuring the consistent reporting of stranded Torpedo Rays along the Cape Cod region. Torpedo Rays are most easily identified by their large caudal fin as well as their well rounded pectoral fins. Compared to other rays, the tail on the Torpedo Ray follows a more typical caudal fin structure rather than a whip-like structure seen in many other rays. In addition to this, their eyes are set much further forward than other rays. Their coloration is most commonly brown on their dorsal surface with white on their bottom surface. As stated previously, a shock organ is present within each pectoral fin which can discharge dangerous amounts of electricity. Because of this, attempting to save a live stranded torpedo ray proves to be much more difficult compared to other marine life. Some suggest that it is safe to gently grab the live animal by the tail and pull it back into deeper water. Dead Torpedo Rays are perfectly safe to touch for the carcass will not shock you. If you find a stranded Torpedo Ray, please report your sighting to NECWA by completing our online Torpedo Ray JotForm.  

 


Our conservation efforts to protect organisms such as the Torpedo Ray are indicative of their true significance to their ecosystem. As we have seen through the strandings of Ocean Sunfish and Sea Turtles, the absence of these organisms means drastic change for the ocean food web. In relation to the Torpedo Ray, they serve as one of the many controllers of larger fish populations with their ability to take down larger prey. If they were absent from the local ocean ecosystem, larger fish populations would surely dominate ocean ecosystems when considering the constantly growing threat to shark populations as well. In addition, Torpedo Rays have proven to yield new discoveries with our limited information on them. 

For example, in 2019,F. NeptalĂ­ Morales-Serna and others analyzed the discovery of a new species of copepod Echthrogaleus spinulus found on a Torpedo Ray. In order to further understand the significance of Torpedo Rays, our conservation and research efforts must be prioritized further. 



Among the well documented strandings of Mola mola, various species of Sea Turtles, and other marine life, Torpedo Rays remain one of the lesser known and less understood marine organisms that are reported to strand. However, a pattern noticed by NECWA is that Torpedo Rays typically strand each fall and early winter along with other marine animals like ocean sunfish and sea turtles. In addition to this, a majority of stranded Torpedo Rays documented bt NECWA appear to be female. Apart from this trend, there is very little information on the specific causes of Torpedo Ray strandings. While the conservation status of the Atlantic Torpedo Rays has not been evaluated, there is still growing concern as an increasing number of Torpedo Rays are stranding each season. Further research must be done in order to hypothesize the root cause of Torpedo Ray strandings. 

Our lack of knowledge on the biology and ecology of the Torpedo Rays and their cause of stranding increases the importance of collecting new stranding data. In order to ensure that Torpedo Rays and any other marine life are protected, it is crucial that any sightings are properly and quickly reported. NECWA proudly strives for the further research of Torpedo Rays and how we can assist with stranding relief efforts.

 

For more information on Torpedo Rays, refer to the studies and links below:


Turtle Journal - Shocking Discovery in Cape Cod’s Loagy Bay: Electric Torpedo Ray


Florida Museum Discover Fishes - Torpedo nobiliana


Biology and Ecology of rays in the Chesapeake Bay, Joseph W. Smith

 

 Fish Base - The Atlantic Torpedo Rays


Vineyard Gazette - Damn those Torpedos



Additional Papers on Torpedo Rays:


Morales-Serna, F.N., Crow, G.L., Montes, M.M. et al. Description of Echthrogaleus spinulus n. sp. (Copepoda: Pandaridae) parasitic on a torpedo ray from the central Pacific Ocean utilising a morphological and molecular approach. Syst Parasitol 96, 777–788 (2019). https://doi.org/10.1007/s11230-019-09885-5

 

A. Fraser-Brunner (1949) LXXIII.—Note on the electric rays of the genus Torpedo, Annals and Magazine of Natural History, 2:24, 943-947, DOI: 10.1080/00222934908654036

Wednesday, July 1, 2020

NECWA's new GoFundMe Campaign to Raise Money for Field Gear

Help Support NECWA through this new GoFundMe Campaign. 

To learn more and donate today, 
click HERE.


Saturday, January 4, 2020

Thresher Shark Strandings on Cape Cod this Fall and early winter.



Thresher Sharks in Cape Cod, MA
By: Cory Farrelly
UMASS Dartmouth Intern

At the end of 2019, there were a number of Thresher Sharks washing ashore on Cape Cod beaches. Thresher Sharks are very unique sharks in the order Lamniformes, which are commonly called Mackerel Sharks. Threshers are easily identified by their extremely long caudal or tail-fin, which they use to stun their prey, making their prey easy to consume. Threshers can be found in the Atlantic, Pacific, and Indian Oceans. These species are highly migratory and can cover vast distances in a relatively short period of time. There are three species of Thresher Sharks: The Bigeye Thresher, Common Thresher and Pelagic Thresher. The Common Thresher is the largest species, reaching a length of 20ft and is the species that is found in New England waters. 


Dead Common Thresher Shark found in Wellfleet, MA
In the fall of 2019, I have responded to 2 stranded Thresher Sharks along the shores of Cape Cod. One shark was found in Uncle’s Tim’s Bridge on Duck Creek in Wellfleet. This shark was unfortunate enough to get trapped in a salt marsh during high tide. When the tide receded, the water most likely got too low for the shark and it could not survive. A local resident had actually seen the shark alive struggling to get out of the salt marsh a few days before. The shark was 6 feet 10 inches long. When we found the carcass, it was partially buried in the mud.
The second Thresher Shark carcass was found on Burton Baker beach in Wellfleet. The carcass was very fresh looking and had bled significantly through its gills. In addition to the blood from the gills, the shark had several marks along its body from Sea Lampreys. It also had interesting marks that appeared to be healed scrape marks on its side. The pectoral fins were completely buried in the sand, which suggested that it washed ashore then thrashed around and buried itself in the sand. This shark’s body was 7 feet long and with its tail it reached a length of 13 feet. 
All three species of Thresher Sharks are classified by the International Union for Conservation (IUCN) as vulnerable. Due to their low fecundity (the amount of offspring they can produce), it is difficult for these sharks to rebound from losses to their population. Thresher Sharks are vulnerable to fishing, both commercially and recreationally. Commercially, their livers are used for oil and their fins are used in shark fin soup. By-catch is also an issue. Every year, 50 million sharks are unintentionally caught and often killed by the fishing industry. Recreational fishing also has negative impacts for the act of being caught can cause undue stress and extreme exhaustion that the fish may not be able to recover from. Many shark populations struggle to rebound from fishing pressures due to their low fecundity and long gestation periods so killing millions every year is detrimental to their populations. Since threshers are found worldwide and are highly migratory, regulations on this species are nearly impossible to enforce because it would require cooperation among many countries. 
To help Thresher Sharks and many other shark species, become more knowledgeable by learning more about them. Limit your seafood consumption, especially various tuna species, and be a choosy consumer using the Seafood Watch app from Monterey Bay Aquarium. Also, do not purchase any shark products, including shark fin soup.  

References for Further Reading