Saskatchewan researcher casting for anglers who can reel in hybrid fish DNA

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REGINA - Anglers in Saskatchewan are being asked to help reel in information about a hybrid fish.

Chris Somers, an ecologist at the University of Regina, is hoping that anyone looking for good fishing holes before an upcoming walleye tournament will bring him a specimen that could be a cross between a walleye and a sauger. It's known as a saugeye.

"What we are trying to do is to get a DNA-based approach up and running to detect hybrids reliably between those two species," said Somers.

"The reason we need to do that is that after a certain number of generations of interbreeding, you can't reliably detect a hybrid by eye, so you need a molecular tool to be able to positively identify something as being intermediate between the two."

Walleye don't have spots on their fins, and the bottom of their tails is lighter with a white tip. Sauger have spots all over the fins, but no light patch on the tail. A hybrid could have some or any of the characteristics.

The first step of Somers's research is to develop a detection method with DNA-based tools ready in the lab. He needs a tissue sample, like from a fin clip, to do the analysis.

"We just take a small piece of the fin from the fish and then we would extract DNA from that fin and we would use ... molecular markers, sort of like creating a barcode for the fish," he said.

"When you go to the grocery store, they scan that barcode in the laser machine there that tells you what product it is. We're creating a similar barcode with pieces of DNA that will tell us whether the fish is a walleye or a sauger or has characteristics of both."

Walleye are more of a lake or deep-water fish, while sauger are usually in turbid or flowing waters, such as rivers.

When the two environments come together — for example, at the spot where the South Saskatchewan River flows into Lake Diefenbaker — they can interbreed to create the saugeye.

Somers says anglers have been speculating about how long saugeye have been around "ever since the first lure went in the water in Canada." What's not clear is how often the two species merge and what role the hybrids play in the fishery or in changing the ecology of fish.

"I don't think anybody is really 100 per cent sure what the consequences of hybridization are," said Somers.

"But some of the things that they might be are a change, for example, in the way that the hybrid fish grows compared with either of the parent strains."

Somers said sauger are a smaller fish that don't get as big as walleye. That would suggest it's possible that hybridization is reducing the growth rate of the intermediate fish that would be less prized by anglers as a result.

"The other possibility is that the hybrids may be less fertile than their parent forms and so, if you have a lot of hybridization occurring, you might actually get fewer offspring produced, and therefore a reduction in productivity of the fish population and ultimately fewer fish in hybrid zones."

Somers and research staff plan to be stationed at the boat launch in Saskatchewan Landing Provincial Park on Thursday and Friday, the pre-fishing period for a big walleye tournament taking place next weekend.

He would like anglers to bring him live fish so a fin clip can be taken. The fish would be returned to the fisherman or released. The other option is to store a dead fish on ice until a sample can be taken. Anglers can still fillet and eat the fish afterward.

"We'll be able to take a look at the fish and ask anglers what they think it is. Is it a walleye? Is it a sauger? Is it a saugeye?

"And then we can start to do a genetic analysis to basically demonstrate one way or the other what the fish was," said Somers.

"I fully expect that anglers will have probably a pretty good feel for the obvious hybrids, but the ones that are a little bit more tricky to tell, that's where I think it's going to get very interesting."

Organizations: University of Regina

Geographic location: Saskatchewan, South Saskatchewan River, Lake Diefenbaker Canada Saskatchewan Landing Provincial Park

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