Rare ice age fish thriving at Grey Mare’s Tail

Transcript

My name's Ciaran Hatsell, and I'm the Head Ranger at Grey Mare's Tail Nature Reserve.

The National Trust for Scotland recently had a big ideas session, and we came up with a huge document and a vision going forward, called the Plan for Nature.

Now the vendace is part of that, because it's a really iconic and really rare species.

So the vendace is the rarest freshwater fish in the UK, and we see it as a species that we really want to do our best to protect and there are lots of challenges in that. It takes a lot of collaborative working so it's a huge effort and we can't do it on our own. We've got to work with lots of other people to make it happen.

This fish is under threat, potentially from several things, but climate change is massive, so we want to try and do what's our responsibility (and an honour) to champion this species in Scotland.

Hi! I'm Martin Lyall, I'm one of the Rangers here at the Grey Mare's Tail Nature Reserve for the National Trust for Scotland.

The Grey Mare's Tail is just an amazing Nature Reserve. We have a little bit of everything. We've got moorland, a loch a waterfall and grassland. We've got a couple of exclosures now with montane species being preserved in them and it just makes the whole place a brilliant little jigsaw.

So, the Grey Mare's Tail is our famous waterfall that is fed from the water of Loch Skeen. It's basically a glacial artefact carved out 12,000 years ago, and it's filled with basically just rainwater and a little bit of peat residue. This makes it an oligotrophic, low-nutrient loch, which makes it the perfect environment for the vendace.

The vendance have two main challenges. The first one is invasive species eating their eggs, which they're very vulnerable to. The National Trust for Scotland has this population, which was put here in 1997, to give them a protected habitat without the many invasive species where they came from. Their second challenge is eutrophication or increased nutrients in the water which affects the bio-system and makes it very hard for them to survive, with the extra competition.

So it's extremely fussy. The vendace is extremely habitat-specific. It needs a deep, nutrient-poor loch that it can survive in. The Loch Skeen is absolutely perfect. There was a feasibility study done, of lots of different lochs all across England and Scotland as well, and this was identified as a really key site for it.

So the translocation to this site in the 90s was done in 1997 and 1999, by a group of experts from various organisations and they basically collected lots of vendace, which was surviving in two places in the Lake District: Lake Bassenthwaite and Derwentwater, so the two places that they thought the fish was going to struggle and the populations were dwindling, and so, people took action. It's quite easy to have ignored this – without the specialists and nature nerds, we'd never have known this was happening.

Vendace are a deep, water-dwelling species, and they're extremely secretive and difficult to monitor. The eggs were harvested from Bassenthwaite, and they were brought up to tiny little fry, really, really small fry and they were brought here in flasks and released into the lochs. So, although we've got all this mad technology, we used a relatively simple process to release them over a period of several months, and as we know, from our previous surveys, (the last survey here was in 2016), the translocation has been a success, and the vendace seem to be thriving in the loch here. From that, potentially, (we've always got to think 'what can we do next?'), so potentially we can then use this as a site to translocate from. We've got to have ideas. There are lots of challenges in that, and it might not be possible, but if you don't think big and think 'how can we look after this species for the future?', then we'd just give up! It's a real honour and a privilege to do that for the Trust.

We're very grateful to our supporters and members for enabling us to continue to understand, care for and protect our natural heritage. Every species we protect is a step towards safeguarding Scotland's nature, beauty and heritage for everyone.