A brief encounter with the UK's rarest freshwater fish

Freshwater ecologist Ian Winfield tells us more about the rare vendace fish and the exciting moment he captured it on film for the first time in the wild in the UK...

For a few years now a fair part of my working life has focused on the vendace, which is the UK’s rarest freshwater fish and has just two of its original four populations still surviving. These occur in the Cumbrian lakes of Bassenthwaite Lake, from which the species was temporarily lost, and the nearby Derwent Water. Our long-term Cumbrian Lakes monitoring programme has shown us that the population in the latter lake has remained robust throughout the last approximately 20 years and currently stands at an estimated 5,000 adults.

Elusive species

The vendace is not an easy species to monitor or study. It spends most of its life in deep, perpetually dark and usually cold waters. The only time it ever comes into shallow water is when it migrates onto its spawning grounds for a few nights during the early winter. Unsurprisingly, no video recordings had ever been made of this remarkable species in the wild. Until last week...

Underwater survey

Working with my CEH Lake Ecosystems Group colleague Ben James, we came to the end of a long and bitterly cold day surveying the condition of several vendace spawning grounds around the edges of Derwent Water using a BioBase hydroacoustic bottom-typing system. This was coupled with underwater video recordings collected using a camera on our remotely operated vehicle (ROV, think of it as a pocket submarine). Although keen to get back to the warmth somewhere, we decided to spend just a few minutes moored up to our deepwater buoy to allow us to pilot the ROV down to the lake bottom at about 20 metres. We immediately found large numbers of perch and ruffe dotted, barely moving, around the bottom where they are known to overwinter before returning to shallower water in the spring.

We also saw something flash past our camera at great speed. I suspected a vendace.

It was with some excitement that once back in the warmth and with revitalised fingers I reviewed the video recording and fast-forwarded (yes, young things, it was recorded on videotape!) to the approximate point at which we saw the mysterious fish speed by our camera. Slo-mo revealed the distinctive body shape and small adipose fin of an undoubted vendace. Moreover, the vendace didn’t just flash by. It struck (or very nearly struck) a perch sat minding its own business on the lake bottom, before looping around and passing back over our ROV.

Needless to say we plan to return with a better camera and more time…

Ian Winfield

Additional information

The filming took place during a habitat survey carried out by CEH and the Environment Agency. The Environment Agency issued a press release about the vendace film.

Read more about CEH's long-term lakes monitoring programme

News story (October 2014) about the re-discovery of vendace in Bassenthwaite Lake

Staff page of Dr Ian Winfield

 

Science areas: 

Issues: