Pikeminnow project may help dwindling sockeye
Volunteer anglers, from left, Gwyn Joiner, George Noordegraaf, Frank Kwok and Dean Werk try to catch pikeminnow on Cultus Lake to be tagged as part of a tracking program Saturday morning. JENNA HAUCK/ PROGRESS
By Jennifer Feinberg
The Progress
Jan 30 2007
A biologist at the local salmon research lab is embarking on an ambitious plan to learn more about the habits of the northern pikeminnow in Cultus Lake.
DFO biologist Christine Tovey said a new acoustic tagging project kicked off Saturday with the help of some local sport fishermen.
The voracious and plentiful pikeminnow is a fish species thought to be preying on young endangered Cultus Lake sockeye. It’s become an issue because the lake-spawning sockeye have been whittled down to critically low numbers in recent years, and part of the problem is thought to be predation.
“We’re really excited about the community members getting involved with the tagging project — especially at this time of year when it’s not particularly conducive to fishing or being out on the lake in general,” Tovey said.
The pikeminnow tagging project is being funded as part of the Cultus sockeye recovery plan under the Species At Risk Act, even though the lake-spawning population didn’t get officially listed under SARA.
“We want to know about the winter habits of the pikeminnow, as well as what’s happening during the transition to their summer spawning and feeding sites,” said Tovey.
Anglers with the Fraser Valley Salmon Society headed out onto the water Saturday to catch pikeminnow from boats in the lake, said society president Frank Kwak.
Why were a dozen or so locals ready to volunteer their time this way?
“We are very definitely concerned with the conservation and survival of the Cultus sockeye, which is being impacted by the north pikeminnow,” Kwak said.
The volunteer anglers were throwing lines from four power boats on Saturday to see if they could catch 25 pikeminnow, with minimum size requirements in mind. They’re cognizant it might be challenging since the species tends to be lethargic and not particularly hungry in colder weather, making them tougher to catch.
Tovey said DFO staff’s initial efforts to catch pikeminnow with a fishing rod “proved to be quite a challenge,” only netting them three fish after five hours of fishing.
“We had a fairly low catch rate,” she said. “The idea for Saturday was that experienced fishers would be putting concerted effort into catching these fish. It’s hard to say how many we’ll catch, but we’ll be adding more tags as we go.”
Once caught, the fish were surgically implanted with acoustic tags by DFO staff. Acoustic receivers in the lake will allow the biologist to monitor and record the depths of the tagged pikeminnow round the clock. The sockeye are also over-wintering in the lake at the same time.
“We want to see if there’s an overlap in the distribution of the two species, which might enable the pikeminnow to be a potential predator of sockeye,” she said. “We’ll be able to confirm the pikeminnow distribution — where are they in the lake and what depths they’re found at.”
There are two types of acoustic tags being used, one has depth sensors for monitoring offshore distribution and the other type, recognized by a faster “ping rate” will be employed later this summer to follow their movements.