Pet dogs trained to sniff out invasive fish species

File photo.

Household dogs are being trained to sniff out invasive fish species.

If successful, the family pet could become a crucial tool in identifying new incursions of invasive fish such as koi carp and catfish, before populations become established.

It is the work of researchers at Waikato University.

Dog training expert and researcher Clare Browne said early research showed dogs could distinguish between plain water and water that came from a tank containing either koi carp or catfish.

The dogs sniffed 17-samples going around on a testing device and then behaved in two different ways.

If they did not detect koi carp they nudged a little lever which brought around the next sample.

The dogs were observed on CCTV by researchers in another room.

Dogs noses have sensory receptors that can detect a huge number of chemicals, many more than humans.

Dr Browne said apart from their remarkable sense of smell, dogs were easy to work with.

"We use people's pet dogs that come in for the day. They get training and some treats and some walks and they go home again at the end of the day.

Dr Nick Ling is an associate professor of biological sciences.

He said dogs were 20 times more sensitive than detection methods used in environmental DNA.

"You could take a one kilo carp and put it in 200 litres of water for a day and you can take a sample of that water and dilute it 10,000-times and the dogs will say yes there has been carp in that water."

Dr Ling said invasive species of fish caused major problems in waterways including in some shallow Waikato flood plain lakes and in the lower Waikato River.

"Koi carp constitute about 70 to 80 percent of the total fish biomass, so they have really taken over the ecosystem."

Dr Ling said the early results using dogs looked very promising and the next stage would go beyond the laboratory.

"In the lab we are working with nice clean water and only looking at one species at a time, so research taking it to the field and look at water samples that are dirty, that have suspended sediment, that potentially have multiple species in them."

Clare Browne said ultimately they hoped to be able to offer a quick and low-cost means of surveying water systems.

"If there is a suspected incursion instead of quite resource intensive methods like sending out people to do netting, maybe we could get some water samples, send them into the lab and get the dogs' assessment."

Dr Ling is not concerned if anyone has questions about the use of dogs in research.

"It has huge environmental benefits and the dogs love it."

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