More studies needed for local fisheries

A decline in large rainbow trout has been noted by anglers over the winter

Area fishermen look forward to spring as the weather warms and diverse hatches of insects emerge on local rivers and lakes, however, concerns over the health of Kootenay Lake and the Columbia River systems has tempered that excitement with concern.

Kootenay Lake anglers had cause for alarm when it was reported that 80 per cent of the fall run of kokanee salmon at Meadow Creek contracted the infectious hematopoietic necrosis virus or IHNV.

In addition to the kokanee at Meadow Creek, tests also showed kokanee salmon at Red Fish Creek and the Lardeau River to be infected with the virus, in what was the lowest return of kokanee (about 200,000) to the main lake since the 1960s.

“Kokanee numbers are on their way down from a peak of – 2011 was 1.7 million kokanee in that escapement estimate, so that’s the number of fish that went to spawn,” said MFLNR Kootenay fisheries biologist Matt Neufeld. “And that’s pretty high, if you look back into the historical records.”

Yet, it is unknown whether the decline in kokanee numbers is attributable to the virus or an abundance of predators like bull trout and Gerrard rainbows, or a combination of factors.

“We don’t know what is driving that for sure,” said Neufeld. “There’s probably several plausible explanations for what’s going on with kokanee numbers. One is that there is lots of Gerrards, or there have been anyways.”

May 2012 saw one of the largest return of Gerrards to the Lardeau River with a day’s peak of over 1,000 fish.

The Gerrard spawning count has seen an “unprecedented increase” in the past 10 years. Before 2011 the highest Gerrard count was about 600 with a low of about 200 in 2001. It set new highs every year since.

“That’s what I’m getting at,” said Neufeld. “Gerrard numbers may be driving kokanee down as we’ve kind of seen this really big peak outside of recorded history.”

The fisheries biologists estimates that if there are 10,000 rainbow and bull trout in the lake and each one feasts on one kokanee per day, that’s 365,000 kokanee per year, a pretty significant dent in the population.

Yet, a decline in large rainbow trout has been noted by anglers over the winter, and would be expected to mirror  a decrease in their primary food source.

Biologists have begun  sampling kokanee fry from spawning channels and from the Lardeau, as well as Gerrards which can also contract the virus.

From these samples, the biologists will try to determine how pervasive the IHN virus is, and its impact on the fish in the long term. (The virus does not affect humans or other animals.)

The falling kokanee numbers has translated into a disappointing winter fishery on Kootenay, with large Gerrard rainbows being fewer and further between than normal.

Kerry Reed of Nelson’s Reel Adventures Sport Fishing Charters noted a slow season that continued into March, yet, he has seen a small improvement with the spring weather.

“We have been noticing a lot more small rainbows showing up now as the weather warms,” said Reed in a recent fishing report. “So, hopefully the big ones follow suit.”

The fishing on Kootenay Lake does seem to be picking up with good catches of rainbows reported last week.  Trail Fire Fighter Grant Tyson landed a 15-pound rainbow, and caught-and-released several in the six to eight pound range.

“It’s one of those wait and see games,” said Neufeld. “Where probably in the short term, kokanee numbers are likely going to be suppressed for the next few years, and what effect that will have on Gerrards we just don’t know yet.”

Smaller fish and lower catch rates will likely be the result of a declining kokanee population, but Neufeld is encouraged by the number of Gerrards that have been counted at the Lardeau spawning grounds recently.

“This year’s spawning escapement, so far anyways at 450 or so, is kind of good news. Given the report we’ve had from anglers, it’s good to see that number of fish there.”

Columbia River

As for the Columbia River, local fisheries attempted to counter the environmental threat to the system posed by an alien species last August.

The Ministry undertook a Pike Reward Program that encouraged anglers to fish for and retain pike caught in the Columbia.

Fisheries technicians released a number of pike after implanting them with a chip, so that if an angler returned a pike’s head with a chip in it they would pocket $500.

“We had lower participation than we hoped for in that program,” said Neufeld. “It might have been timing or something with rolling that out, but we had a very small number something like 20 heads returned.”

The slight number of returned heads, however, does not necessarily indicate that there are fewer pike in the system than expected.

“It’s hard to say. We did some work catching pike out there to implant tags, and there were lots of large fish out there in the seven to 15 pound range, so I’m not convinced that’s the case.”

Most of the pike were caught in the Robson reach stretch of the Columbia, but some were landed near Waneta and in the Seven Mile Dam Reservoir.

Index studies done on spawning rainbow also suggest a growing number of pike in the Columbia.

“Those (pike) numbers have been kind of increasing over the last five or six years in that program, and so the indications are that pike are there and there’s probably quite a number of them, but we just haven’t done quite enough work there to know for sure what’s going on.”

The apex predator also brings disease concerns, and while the rainbow trout population is apparently robust at the moment, the long-term affect that pike will have on them is troubling.

“We don’t know what they’re eating yet, but there is scientific literature that suggests they prefer soft bodied prey like rainbows or kokanee over perch or other fish, so the jury’s still out on how big an impact they will have in the long run, but there certainly are some concerns.”

The Pike Reward Program expired at the end of March, and fisheries is still considering how best to attack and eraticate the invasive species. Until then Neufeld reminds anglers that there is an unlimited quota on pike, and he encourages fishers to retain all pike caught in the system.