Sunday, October 28, 2018

Fisheries managers open bull trout on Duncan River in effort to help Kootenay Lake kokanee

The kokanee salmon numbers are rising slowly but surely on Kootenay Lake, and fisheries managers are taking additional steps to help them recover. 
Effective Oct. 5, the Ministry of Forests, Lands, and Natural Resource Operations (FLNRO) reversed the freshwater fishing regulations on the Duncan River, taking down the ‘no fishing’ signs and opening the river to angling. The new regulations will up the bull trout daily retention quota to two per day, while making it catch-and-release for all rainbow trout caught below the confluence with the Lardeau River. 
“We’ve looked at the diet of predators, both rainbows and bull trout, over the last two-and-a-half years and we’re continuing to do that, but what it showed is that bull trout are really effective at eating kokanee - even at low densities, and rainbow’s are switching, becoming insectivores,” said FLNRO’s Kootenay biologist Matt Neufeld. 
In February, Fisheries also increased the daily quota for bull trout on Kootenay Lake from one to two (only one over 50 cm.) and rainbows from four to five. 
Gerrard rainbows are adapting and feeding more on insects and mysid shrimp, and because of that, they are not growing to the size that many anglers have grown accustomed. Bull trout, conversely, aren’t as adaptive. 
“We thought they (bull trout) would be eating white fish and a bunch of other things,” said Neufeld. “At least the samples we’ve collected from the main body of the lake show that more than 70 per cent of their diet is kokanee still. And they’re better at getting kokanee at low densities.” 
Despite a drastic decline in kokanee populations, the bull trout numbers increased by more than 100 per cent between 2015 and 2017, with approximately 3,500 bull trout spawners in 2017 alone. 
Bull trout are more effective at feeding in deep water than rainbows, and that is where the kokanee fry and one-year olds go after feeding. 
“Bull trout are better adapted to dark conditions, so they’re just hanging out in the deep feeding on kokanee, whereas rainbows aren’t as effective at doing that. So it sounds like bull trout are the big problem.” 
Studies indicate that about 95 per cent of kokanee fry don’t last a year, added Neufeld, with bull trout being the main culprit in decimating the population. 
“You just can’t recover kokanee when that is happening. So we’re doing a few things, we’re continuing to stock kokanee, but we’re also reducing predation pressure. That’s been done in a few ways, we changed regulations for rainbow trout and bull trout. We’re encouraging people to harvest fish, both rainbows and bull trout.” 
The kokanee numbers are nowhere near their historic highs, peaking at about 2 million, but the landlocked salmon is slowly rallying and coming back from a low of about 15,000 spawners on the main lake in 2017 to about 30,000 this year. 
“They (the kokanee) are super big, so if you compare them to those bigger number of spawners - they would have been much smaller and had fewer eggs.” 
The large kokanee in this year’s return will carry 600-800 eggs, while the smaller Kokanee in past larger populations had a capacity of about 200 eggs. 
“So really you can triple that number, so the 30,000 is more like 90,000 if you compare the size, but it’s still super low.” 
Fisheries also planted about 16-million kokanee eggs over the past three years in various tributaries and will add another five-million this year in an effort to bolster the population. 
The West Arm kokanee are independent of the main lake kokanee, and Neufeld was optimistic by what he saw, adding that the West Arm kokanee were actually benefitting from low densities on the main lake, due to an increase of food (ie; daphnia and zooplankton) washing into the Arm. 
“West Arm was great this year, they’re super big fish,” said Neufeld. “We’re going to be around 16,000 spawners, which is really on the high end, especially given the size that we’ve seen in the West Arm.” 
Anglers can attest to the large kokanee catch and its respectable numbers, as about 8,000 were harvested from the Upper West Arm this year over the 12 days the kokanee fishery opened, running the first three days of April, May, June and July. 
Following the kokanee collapse, the Gerrard rainbow trout numbers plummeted, leaving the fishery and area businesses reeling. 
From a high of over 1,500 in 2012, the Gerrard spawners in the Lardeau River have averaged 100-150 spawners in recent years. Still, Neufeld is encouraged by the numbers of rainbow trout he sees in Kootenay Lake. 
“We think there are many more rainbow trout in the lake … the catch rates for rainbows are high, but they’re all small.” 
The big question for fisheries biologists was whether the smaller rainbow trout were Gerrards or another species that fed mainly on insects? 
“We used genetics to evaluate,” said Neufeld, adding that the studies found,”Still about 75 per cent of that catch are Gerrard rainbows.” 
While, there is no conservation panic for the Gerrards, the days of the 15-to-25-pound lunkers likely won’t return until kokanee numbers improve. 
“The capacity of Gerrards to produce 20 pounders has not gone away, it’s just limited by kokanee supply,” added Neufeld. “They just can’t get bigger than two-and-a-half or three pounds eating bugs. The energy expenditure is just too high.” 
So fisheries managers are encouraging Kootenay Lake anglers to take advantage of the new regulations and actually hasten the return of the kokanee population by harvesting more bull trout and rainbows. 
“The good news for Gerrards at this point, is we’re still getting spawners, and we know that spawner number is producing a decent juvenile supply,” said Neufeld. “So they (Gerrards) are not gone, they’re sitting there waiting to take advantage of the situation when things improve.” 
See for changes. 

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