Gene bank will pay off

SCIENCE is playing an increasingly significant role in restocking projects, particularly in the field of applied genetics.

Every wild fish that comes into the Drimsallie hatchery is genetically screened, most of them overseen by Eric Verspoor, director of the Rivers and Lochs Institute at Inverness College UHI.

Jon Gibb said they were looking for pure, indigenous fish, weeding out Norwegian genes, and also making sure they don’t cross siblings later on.

As well as screening the Lochy’s smolts, Drimsallie is also used by the ongoing Upper Garry Salmon Restoration Project, run by the Ness District Salmon Fishery Board and part funded by Mowi.

Wild River Garry salmon smolts were captured on their journey downstream to the sea and grown on to maturity at Drimsallie, with the first eggs stocked in the Ness last year.

Each smolt, when captured, was fitted with a passive integrated transponder, which allowed each fish to be identified in future. Genetic profiling ensured the fish used in the project were of the correct, indigenous stock.

In 2018, some 23,500 eggs were stocked across eight sites, and from this year, up to 150,000 eggs will be stocked each year for the next three years.

Gibb said there is ‘an element of insurance policy’ about the genetic screening in all the projects.

‘There is one tank of fish outside [at Drimsallie] where there is probably more fish in the tank than there is in the river. So you start to think, as stocks collapse, you become a live gene bank.

‘The fish in one tank are from the Strontian where there are basically no fish in the river. We’re bringing them on to adults.’

Another insurance policy at Drimsallie involves taking the milt from the male fish and then sending it to a Norwegian company called Cryogenetics, which cryopreserves it in tanks of liquid nitrogen.

The technology is not yet developed to cryopreserve eggs, but once it has been these will also be sent to Norway.

‘Genetic material from each of the rivers is being stored so you can then use that milt, un-cryopreserve it, and cross it with eggs,’ said Gibb. ‘So you’re preserving perhaps even the last remnants of some of these populations.

‘That should be a national project…it’s of national interest to have a preserved gene bank of all the rivers.

‘There is, in fact, a national project in Norway where milt from threatened rivers are all cryo-preserved and we should be doing the same here in Scotland.’