A mountain search and rescue responder has trained her hero dog to sniff out invasive “sea vomit” in what is believed to be a world first. Dr Texa Sim’s two-year-old labrador, Uisge, can detect Didemnum vexillum, an invasive marine organism that has been found in UK waters. 

The species, commonly known as sea vomit, originates from Japan and is often transported across the world on the hulls of ships. This fast-spreading sea squirt can clone itself, forming thick, carpet-like colonies that smother the seabed. If left unchecked, it can blanket entire areas, driving out native species and damaging biodiversity. It also poses serious problems for the fishing industry, particularly shellfish farms.

Dr Sim, 33, has also trained her five-year-old search and rescue dog, Sgiath, to detect invasive marine species.  Detection dogs are widely used on land to locate invasive plants and animals but Dr Sim saw an opportunity to bring that approach into the marine environment.

She said: “Detection dogs are really common for invasive species work in the terrestrial environment and I also have a background in marine science. When I was considering what I would like to train the dogs on — something interesting, novel and impactful — I realised not many people are doing marine invasive species work, even though it’s a huge global problem.

“Ocean temperatures are changing. We’re creating conditions where some of these species can get a really firm hold on ecosystems where they didn’t originate. If they do crop up, you need to report them as quickly as possible.”

The first UK recording of sea vomit was in Wales in 2008. It has since spread to England and Scotland. Dr Sim, the first employee of the Community Association of Lochs and Sounds, supported by Fauna & Flora, converted her garage into a training space.  She built a practice wall where she hides samples of the invasive species for the dogs to locate by scent.

Sgiath continues to work alongside Dr Sim with the Glencoe mountain rescue team, which operates around the clock to find missing people in the Scottish Highlands. Although she did not grow up with dogs, Dr Sim learned about scent training through mountain rescue and began focusing on ecological detection work in 2022. 

Part of her role involves confirming when invasive species are not present — something she said is just as important as detecting them.

She added: “To my knowledge, there are no dogs trained on this species anywhere in the world. 

“It was very experimental. I had to design ways of training and testing the dogs to prove they could recognise the scent and differentiate it from others in that environment.

“I was blown away by their ability. Once they understand the scent you’re asking them to find, they can generalise it across different tasks and setups. It’s phenomenal what they can do.”

She hopes more handlers will begin training dogs to tackle marine invasive species. Labradors are her “breed of choice”, describing them as level-headed, adaptable and highly driven.

“A lot of people think ‘lazy labradors’ but they’re anything but,” she said. “They are absolutely switched on and will work for as long as you ask them to — and they’re wonderful to live with too.”

Biosecurity is central to her work. 

The dogs are trained to freeze when they locate the highest concentration of sea vomit, avoiding contact and preventing further spread.

Dr Sim said: “You’ve got excitable dogs doing what they’re born to do — searching and hunting — and then you’re asking them, at the most exciting moment, to stay completely still.

“You have to make sure they understand that the stillness leads to the reward.”