New Study of Two Beautiful Angular Rough Shark (Oxynotus centrina) in Malta Waters

A new study published in the Journal of Fish Biology by Lydia Koehler of Sharklab Malta gives new insight into angular rough sharks (Oxynotus centrina) in coastal waters of Malta. These rough sharks are deep sea sharks, spending the majority of their time between 60 to 600 m in the Mediterranean Sea (Serena, 2005).

Angular-rough-shark-Oxynotus-centrina-observed-in-coastal-waters-off-Yass-ada-in-2000
Ceylan, T. (Photographer). (2000). Angular rough shark, Oxynotus centrina, observed in coastal waters off Yass [Digital Image]. Retrieved from https://www.researchgate.net/

Catch data in the Mediterranean from 1994 to 1999 from 10 to 800 m as part of the Mediterranean International Trawl Survey recorded the angular rough shark as 0.6% of the tows. The majority of those caught were between 100 to 200 m (STECF, 2004). Their regional biomass indexes suggests the species is more common throughout western central Mediterranean, in areas around Corsica, Sardinia, and Sicily, with lower biomass indexes in the western and eastern areas near Morocco, Spain and Aegean (STECF, 2004). The new study reports two individuals were caught in Malta within a few weeks of each other.

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Fig. 1. Map of Malta showing the bathymetry catch area of two Oxynotus centrina and the release area of the surviving male (Koehler, 2018).

 

It is incredible enough to find one angular rough shark in Malta waters, but this study documents two that were found within just 3 weeks of each other. The first was a female caught in a trammel net, at a depth of approximately 60 m on the evening of May 13 – 14 th, 2018. This female was landed dead and was stored frozen until permits could be obtained for dissection (Nature Permit 0139_17). The following table shows the body measurements that were taken from the female. If you’d like to read further into the report, the link to the study can be found below as well.

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Table I. Morphometric measurements from reported female Oxynotus centrina (Koehler, 2018)

 

The male, caught on the night of June 2 -3, 2018, was presumably caught in the same manner between 60 to 100 m. I say presumably because this male had been abandoned, left entangled in a net for over 17 hours by the time Sharklab Malta was notified. At which point he was placed into a bucket of seawater where he was in very poor condition. He was immediately transferred to a larger container so the team could assess his breathing. They attempted to pump seawater over his gills using a plastic bottle. Within an hour, he began to show signs of revitalizing!

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Fig. 2. Different stages of the rescue of the male Oxynotus centrina (535 mm total length) showing (a) the state at encounter, (b) the inability to maintain buoyancy, (c) the reintroduction into the water with support by snorkeler and (d) the recovered shark swimming on its own (Koehler, 2018)

 

Watch the incredible team at Sharklab Malta and the little angular rough shark that could!

 

Sharklab Malta (2018 June 16). Rescue of an angular rough shark [Video Clip]. Retrieved from https://www.youtube.com/

While the longevity of this little rough shark is unknown due to the team’s limitations, he showed incredible signs of improvement over the time the team spent with him. Hopefully he is still going strong. This brief interaction gives insight for future encounters with these sharks and potentially for other landed species to aid in post-capture recovery. Well done to the team at Sharklab Malta! If you’d like to read the full article, please visit: New records of angular rough sharks Oxynotus centrina in the coastal waters of Malta, with observations on post-capture resilience and release behaviour

Read about more rough sharks here: Featured Species Friday: Prickly Dogfish (Oxynotus bruniensis) and here Featured Species: Caribbean Rough Shark (Oxynotus caribbaeus)

If you missed the new study that tracked basking sharks in the eastern Pacific Ocean using satellite telemetry, go back and check it out! It’s a really neat study that gives us insight to a population of basking sharks that we still don’t know much about.

I want to thank you for sticking with me while I took a little time away for my graduate studies and a few personal projects. The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!

Remember you can make a difference for marine ecosystems by contacting your Congress man or woman and telling them that you care about the quality of our waters! Sharks, rays, and other marine organisms cannot speak or be represented in Congress. They need your voice. Get involved and stand up for sharks. Until next time finatics.

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Featured Image Source

Sharklab Malta (Videographer). (2018). Rescue of an angular rough shark [Video Screenshot]. Retrieved from https://www.youtube.com/watch?v=BLuVexLjQNM

Literature Cited

Bradai, M.N., Serena, F., Bianchi, I. & Ebert, D.A. 2007. Oxynotus centrina. The IUCN Red List of Threatened Species 2007: e.T63141A12622296. http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63141A12622296.en

Koehler, L. (2018). New records of angular rough sharks Oxynotus centrina in the coastal waters of Malta, with observations on post‐capture resilience and release behaviour. Journal of fish biology92(6), 2039-2044.

Serena, F. (2005). Field identification guide to the sharks and rays of the Mediterranean and Black Sea. Food & Agriculture Org.

STECF. 2004. Commission Staff Working Paper: 17th Report of the Scientific, Technical and Economic Committee for Fisheries. Commission of the European Communities, Brussels.

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