SCUBA News 244
(ISSN 1476-8011)
27 October 2020

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SCUBA News (ISSN 1476-8011)
Issue 244 - October 2020
https://www.scubatravel.co.uk
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Hello - welcome to SCUBA News. Many of us are desperate to go diving abroad, but it's not easy. However, liveaboards are running and there are some bargains to be had if you book a trip, including to the Red Sea, Galapagos and the Maldives. Look out for booking conditions which allow trips to be rescheduled or refunded if affected by COVID-19 restrictions, and insurance that covers COVID-19.

What's New at SCUBA Travel?

	Identify Red Sea Fish Identify the sea life you see whilst diving, not just fish but coral, turtles, nudibranchs... READ MORE…
	Maldives Magic The Maldives is open with some great liveaboard deals now available. It is the perfect place to dive with manta rays. LEARN MORE…
	Diving Guide to the Canary Islands With COVID-19 cases rapidly declining in the Canary Islands they are a good option for some European winter diving. LEARN MORE…

Creature of the Month: Oceanic Whitetip Shark, Carcharhinus longimanus

Diving with Oceanic Whitetips

The glorious oceanic whitetip sharks spend a lot of time in shallow water, tend to swim slowly and are very curious. All of these mean that divers can get superb closeup view of them.

They are easy to distinguish from the reef whitetip by their more substantial bodies, the pilot fish that continually accompany them and their rounded fins. A beautiful and awe-inspiring shark.

If you should see an oceanic whitetip, keep calm, keep facing it and move very slowly. Treat it with respect as it can be dangerous.

Oceanic whitetips used to be the most common pelagic shark in the sea, but now they are critically endangered. The best places to encounter them are at Elphinstone reef in the Red Sea, and Cat island in the Bahamas.

Oceanic whitetip shark with pilot fish. Photo credit: Johan Lantz (CC BY 3.0).

Why is it endangered and how many did there used to be?

The reason it is now endangered is mostly due to fishing. In some areas it is deliberately targeted plus it is often caught as bycatch and retained for the meat and fins. The fins especially are highly prized in some markets like Hong Kong, being large and thought of as good quality. The same reasons that it encounters divers means that it is very catchable. Their numbers have declined terribly throughout its range. Scientists estimate that the population of oceanic whitetips has declined by over 98% since the 1960's.

Compounding its problems is its slow replenishment of numbers. It's thought female sharks reproduce just every other year and pregnancy lasts 10 to 12 months. Smaller females might have just one pup, although large sharks might have as many as fourteen. But the sharks are getting smaller. Female sharks don't mature until between 6 and 8 years old and only live until around 18. They give birth to live young. The average population increase per year in the Atlantic - the r number we are now all so familiar with - is just 0.126 a year.

Oceanic whitetip shark on Elphinstone reef. Photo credit: Alexander Vasenin (CC BY-SA 4.0).

There is hope for the shark though. This year the UN countries agreed to list Carcharhinus longimanus on Appendix 1 of the Conservation of Migratory Species of Wild Animals (CMS). This is the highest level of protection possible.

The travelling shark

This large shark grows to 3.5 m long, but individuals this large are rare. It roams throughout the tropical and temperate seas, however, it seems to prefer waters above 21 ^oC. Although mostly keeping to shallow waters, it has been known to dive to depths of over 1000 m. They travel great distances in open ocean - one was tracked as far as 6500 km over 100 days. However, they also appear to regularly return to favourite areas. Sharks tagged in the Bahamas stayed within 500 km of the tagging site for around a month before moving to several different destinations across the western North Atlantic. After five months they were back.

Class: Chondrichthyes > Order: Carcharhiniformes > Family: Carcharhinidae > Genus: Carcharhinus > Species: Carcharhinus longimanus

Further Reading and References

Chelsey N. Young . John K. Carlson 2020. The biology and conservation status of the oceanic whitetip shark (Carcharhinus longimanus) and future directions for recovery. Rev Fish Biol Fisheries (2020) 30:293-312

Rigby, C.L.et al 2019. Carcharhinus longimanus. The IUCN Red List of Threatened Species 2019: e.T39374A2911619.

Rui Coelho et al 2009. Notes on the reproduction of the oceanic whitetip shark, Carcharhinus longimanus, in the southwestern equatorial Atlantic ocean

Urgently needed protection granted to Oceanic Whitetip Shark, SCUBA News 2020

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Diving News From Around the World

Our round up of the best underwater news stories of the past month. For breaking news see our Twitter page or RSS feed

	Tumble drying your clothes damages sea life Tumble drying in a washing machine releases microplastic fibres as "laundry lint" which damages the gills, liver and DNA of marine species
	Efforts to tackle shark fin trade need to focus closer to shore, study says A new study has found that shark fins being sold in Hong Kong, Vancouver, San Francisco and northern Brazil originated mostly from shark species in coastal waters, rather than the open ocean.
	Humpback whales in Alaska are enjoying the cruise ship-free waters Alaska is usually overwhelmed with cruise ships and tourists in the summertime, but not this year. Tourism has come to a grinding halt due to the pandemic, and while it has been a disaster for the local economy, the state's humpback whales seem to be enjoying the calm waters.
	The world's banks must start to value nature and stop paying for its destruction As a new report spells out how financial institutions contribute to biodiversity loss, the clamour is growing for a new approach.
	Sound waves show warming oceans Monitoring the temperature of ocean waters has been a priority for climate scientists, and Caltech researchers have discovered that seismic rumblings on the seafloor can provide them with another tool for doing that.
	Fish save energy by swimming in schools Using biomimetic fish-like robots, the researchers show that fish could take advantage of the swirls of water generated by those in front by applying a simple behavioural rule.
	Green Turtle numbers up in Florida Green turtle nest counts are the fifth highest recorded since 1982, in a year when their numbers were supposed to be down
	What if underwater robots could dock mid-mission to recharge and transfer data? Robots can be amazing tools for environmental studies, but eventually they must return to a base to recharge their batteries and upload their data. That can be a challenge if the robot is an autonomous underwater vehicle exploring deep ocean waters.

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Photo credits: Tim Nicholson, Jill Studholme, Kristin Riser, Jianye Sui

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