Seeking Swordfish, Landed Green-eyed Shark - (Belated) Observation of the Week, 3/29/20

Our (belated) Observation of the Week is this incredible Centrophorus shark, seen off of the Cayman Islands by @captjohndmcdow.

Note: I originally reached out to John about his observation in late March, but due to extenuating circumstances he wasn’t able to reply until recently, so I’m posting this a bit late. - Tony

 A researcher with a masters in fisheries ecology from Texas A&M University, John McDow was swordfishing off the southern shore of Grand Cayman when he came across the shark you see above. “We were deep-dropping squid in about 2300' of water and drifting into the 1400' range before resetting,” he recalls. 

This shark picked up the bait as soon as it hit the bottom on one of the drops. It didn't put up much of a fight and we thought it was a pomfret or barrelfish. When it made it to the surface I saw it was a shark and I knew it wasn't a species we had seen before. We took measurements as quickly as we could and got several photos before releasing it. The shark swam off strong despite being brought up from such a depth.

The shark John and his companions landed was only the tenth individual of its genus posted to iNaturalist (there are now eleven), and as you might ascertain from his tale it’s a deepwater dweller. Like many deepwater marine denizens, not much is known about it, but the large distinctive green eyes are thought to help it see as it hunts for prey so far beneath the surface. Look closely and you can see it has spines on both dorsal fins. Unfortunately, sharks of this genus are vulnerable to the trawl fishery, such as this example from Australia:

Graham et al. (2001) reported declines of 98.4–99.7% in the relative abundances of C. harrissoni, C. moluccensis and C. cf. uyato off the upper slope of New South Wales between 1976–77 and 1996–97. (White et al. 2008)

John (above, with his daughter and a scarlet snake) began exploring the bays, marshes, and beaches of the Gulf Coast when he moved there as a teenager and is now researching the seasonal migratory patterns of tarpon (as well as working a fishing guide). He’s only recently joined iNat, but tells me “I love iNaturalist. It is a great resource and a good place to network with other nature enthusiasts. What I love the most about iNaturalist is that my kids also love it and now they want to go herping or snorkeling to find a species they saw on inaturalist or to get a new photo to submit.”

- by Tony Iwane


- In addition to marine life, John is also into herping - take a look at his observation of a tree-climbing Cayman Racer!

- Like so many observations, John’s Centrophorus benefitted from the knowledge of experts thousands of miles away. @clinton, iNat’s top elasmobranch identifier, resides in New Zealand, and @willwhite, and expert in this genus, lives in Australia.

Posted by tiwane tiwane, May 21, 2020 05:23

Comments

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What an amazing-looking shark John! Thanks for a really cool observation.

Posted by susanhewitt about 1 month ago (Flag)
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A very beautiful looking specimen. Glad you got it back in the water quickly and it seemed okay. A fishing story you'll never forget!

Posted by koaw about 1 month ago (Flag)
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Neat opportunity for a glimpse into the depths...

Posted by chlorophilia about 1 month ago (Flag)
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Wild!

Posted by mmulqueen about 1 month ago (Flag)
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Wow!

Posted by korinnadomingo about 1 month ago (Flag)
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Fantastic! What a wonderful find. Thank you for posting.

Posted by karenmccourt about 1 month ago (Flag)
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Wow, that is so cool! Congrats!

Posted by allycouch about 1 month ago (Flag)

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