To save endangered salmon, scientists use 20-year-old frozen sperm

In an effort to restore dwindling salmon stock, the Spruce City Wildlife Association has partnered with the Carrier Sekani Tribal Council in Prince George to use 20-year-old cryogenically frozen salmon sperm to fertilize salmon eggs.

To ensure it gets a wide range of genetic diversity, the wildlife association's hatchery is using a mix of the decades-old sperm, also called milt, and combining it with more recently collected milt, in hopes of bolstering the number of chinook in the Endako River.

"I think that this is pretty groundbreaking stuff," said Dustin Synder, vice-president of the Spruce City Wildlife Association. 

"The foresight the Carrier Sekani Tribal Council had years ago to take this, and, you know, they've been paying to have it stored for all these years, it was a pretty big thought and a pretty innovative situation."

This is the first time that 20 year-old cryogenically frozen salmon sperm has been used in B.C., Maureen Ritter, managing director at Canada Cryogenetics Services, told CBC Radio West host Sarah Penton.

It's quite common for cryopreservation to be used with new technology, but it's extremely rare for it to be used with 20-year-old materials, she added.

"The fact that they've actually pulled some out and used it is huge. They're testing it [and] they're reintroducing some of those genetics," said Ritter.

Low salmon numbers

While salmon numbers have been low for the past several years, this year was particularly bad. Poor returns were  made worse by a massive rock slide in the Fraser River near Big Bar which, despite relief efforts, prevented many salmon from migrating.

After months of work by officials to try to open up the blockage in the river, approximately 170,400 salmon have swum past the slide. 

"Thank goodness, there are some fish showing up for sure, but definitely a fraction of what there normally would be," said Snyder.

"The goal with our hatchery is to make things better in the world of salmon. And so, when our stocks are already set as endangered by the committee on the status of endangered and threatened wildlife in Canada (COSEWIC), it really, really puts a damper on things when this sort of thing happens."

Christina Ciesielski, fisheries program manager for the Carrier Sekani Tribal Council, said it decided to try using the salmon milt it had been storing for 20 years after having it tested for motility and discovering it was still 80 per cent viable.

"It was a difficult decision. I mean we did wonder if we should just let them spawn naturally and maybe try next year and hope for more fish returning," said Ciesielski.

"We didn't even know if there would be any fish coming back to the Endako, but luckily they made it and some of them were pretty beat up and you could tell they had missing skin from their heads from down at the slide trying to get past." 

Testing

So far, 2,000 eggs that were collected this year are being tested with the cryogenically stored milt.

They will know in about a month if it's successful. However, Snyder is very hopeful it will work.

"There's little to no enhancement going on in our region, so to be able to build these partnerships and do this sort of thing is is really, really innovative for us and gives us the confidence when we're successful in doing it to be able to do it more and build on it," he said.