Tristan da Cunha Conservation News
News and reports from the Tristan da Cunha Government's Conservation Department.

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Three Elephants Seals on Boatharbour Beach

Report from Kelly Burns and photograph from Shane Green

Elephant Seals at Boatharbour Bay

Three Elephant Seals or Sea Elephants (Mirounga leonina) were seen hauled out together
on the beach at Boatharbour Bay on 30th March 2017. Could they be a family?

Swallow sighted at Tristan

Report and photos from Shirley Squibb

Shirley reports 'There has been some excitement this morning (21st March 2017) when a swallow was sighted flying about the factory as staff arrived at work. Employees have spotted swallows, in larger numbers, in the area in the past.'

Shirley's photographs taken from near the factory on 21st March show
the swallow with its distinticive aerodynamic shape flying over the Tristan village.

Editor's Note:

Peter Ryan's Tristan Field Guide lists the barn swallow Hirundo rustica as a commonly observed vagrant bird on the islands. The birds breed in North America and migrate southwards to South America for the southern summer. Most Tristan records have been of juvenile birds. The birds catch insect prey and often perch on wires or under eaves of buildings. The barn swallow has a distinctive forked tail which can't be checked in Shirley's photos, so it is hoped others may have photos or help with a positive identification to help develop this interesting story.

Tristan waters provide refuge for near-threatened blue sharks

Report and photos from Chris Thompson

Blue sharks (Prionace glauca) are one of the great ocean wanderers. These slim, graceful sharks with large eyes and brilliant blue backs are known to make journeys of up to 9,200km (5,700 mi) with some individuals making multiple trans-Atlantic crossings.

Unfortunately these incredible travellers are at great risk from modern fishing practices. They are the most heavily fished shark in the world with many millions taken annually. They are predominantly caught as bycatch as their meat is little valued. However, their large scythe-shaped fins are highly prized in the fin trade and thus they are often taken for their fins—their carcasses discarded at sea.

An adult blue shark inspects the camera on one of the mid-water camera rigs

While their IUCN status is near threatened, a reduced catch rate of 60-80 percent has been reported in recent years and the available data is considered inadequate to accurately assess global population declines.

The footage collected on our pelagic cameras, however, suggests that the waters of Tristan da Cunha may provide a refuge for these gentle giants. As part of the Pristine Seas science program we have been using remote cameras known as mid-water stereo-BRUVS (baited remote underwater video systems) to non-destructively sample the pelagic wildlife found in the open ocean. These rigs are allowed to drift in offshore waters for two hours per deployment, allowing us to identify, count, and measure the pelagic wildlife occupying these waters including sharks, whales, dolphins, turtles, tunas, and forage fish. These unique camera systems allow a glimpse into one of the most understudied habitats on the planet: the open ocean.

A tagged adult female blue shark swims away; this tagging will allow the science team
to learn more about movements of the sharks around Tristan waters.

While their IUCN status is near threatened, a reduced catch rate of 60-80 percent has been reported in recent years and the available data is considered inadequate to accurately assess global population declines.

The footage collected on our pelagic cameras, however, suggests that the waters of Tristan da Cunha may provide a refuge for these gentle giants. As part of the Pristine Seas science program we have been using remote cameras known as mid-water stereo-BRUVS (baited remote underwater video systems) to non-destructively sample the pelagic wildlife found in the open ocean. These rigs are allowed to drift in offshore waters for two hours per deployment, allowing us to identify, count, and measure the pelagic wildlife occupying these waters including sharks, whales, dolphins, turtles, tunas, and forage fish. These unique camera systems allow a glimpse into one of the most understudied habitats on the planet: the open ocean.

An adult female blue shark is fitted with a tag by the Pristine Seas science team

During this expedition by far the most prevalent species we have encountered on the footage is the blue shark. Tristan da Cunha's waters harbour more blue sharks than we have seen in any of the other locations we have sampled all over the world, and what is most interesting is the composition of the blue shark population here.

We are seeing only large females and very small juveniles, suggesting that the waters of Tristan da Cunha might be a blue shark nursery ground with large females traveling here to give birth; the lack of intense fishing effort seen in other parts of the world providing a sanctuary for the pups to grow in peace before undertaking migrations of their own.

A small blue shark pup, as seen in the footage from a pelagic camera deployment off Tristan da Cunha

In addition to the sharks seen on camera, the team has also managed to tag three large female blue sharks. This will enable us to learn more about the movements of these animals and see whether they are resident to Tristan waters or if they make the long migrations their kin are known to undertake.

Blue sharks may not be the only sharks using Tristan waters as a nursery ground, a single small Porbeagle shark pup (Lamna nasus), a smaller relative of the Great White and Mako known predominantly from the population surrounding the U.K., was also recorded on camera. At approximately 60 cm (2 ft), this observation is a first for Tristan waters and suggests it was likely born in these waters.

An adult blue shark inspects the bait canister on one of our mid-water camera rigs

It may be that the very fact of Tristan being the most remote inhabited island in the world is what provides the protection these mothers and their young need from the fishing fleets which they are so vulnerable to.

If going forward these waters continue to be protected from offshore fishing it could provide a much needed refuge for these sharks and other pelagic species.

Saint Mary’s school and Conservation Department Tree Planting

School students have helped plant two coniferous pine sapplings to replace a mature tree that was destroyed by a storm.
12-Mar-2017
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St Mary's School party's day with expedition team

A party from St Mary's School Tristan da Cunha spent the day aboard the Pristine Seas Expedition ship SVS Grenville on 2nd February.
8-Mar-2017
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Expedition arrives back in Cape Town

On arrival in Cape Town the Pristine Seas Expedition thanks its Tristan hosts.
20-Feb-2017
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Tristan group spend day aboard SVS Grenville

As the expedition draws to a close, a group led by Administrator Sean Burns, and including Island Councillors, see for themselves the expedition's work.
13-Feb-2017
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Pioneering surfing off Inaccessible Island

Expedition team members surf Blenden Hall Beach in what could be a first-time surfing experience off the Tristan Islands.
12-Feb-2017
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National Geographic 'Pristine Seas' team visits the settlement

The 'Pristine Seas' team visited the settlement on the 3rd and 4th February 2017 to report on their project and visit the island's tourist attractions.
7-Feb-2017
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