Initial counts of this year’s Okanagan Lake shore-spawning kokanee indicate things haven’t improved from last year, when there was a mysterious plunge in their populations.
Stock assessment biologist Paul Askey with the Ministry of Forests, Lands and Natural Resource Operations says although the numbers are low, there is naturally quite a bit of fluctuation in the numbers of shore-spawning kokanee that return to spawn every year.
He said he’s more concerned about the low stream-spawner numbers this year, particularly since they are a larger kokanee and are more likely to be targeted by recreational anglers.
However, he says the numbers of both stream and shore-spawners is going down at the moment.
He’s concerned that the lake is not a very productive environment now and that’s limiting the total number of kokanee that can survive the three or four years there before returning to spawn before they die.
Kokanee are a freshwater salmon, and follow similar cycles to their saltwater cousins, swimming upstream and spawning where they were born before dying.
The kokanee that returned to spawn on shore this year came from parents born in a year that was also low in numbers, so he’s not surprised at the low numbers.
He has no answers for the decline, but says there have been no drastic changes that might be accountable for the drop. He figures it’s a combination of factors.
Efforts to restore habitat in both Mission and Penticton Creek could improve numbers, but that depends on the lake’s conditions, he said.
Next year could be a better year as there were a higher number of smolts four years ago, when they would have been born.
It’s still believed the the introduced Mysis shrimp compete with young kokanee for feed in the lake, even though they also provide feed for more-mature fish that survive that early competition.
Another fish count was conducted in Wood Lake this fall, but numbers of returning spawners was so low, it was an easy task, he said.
He doesn’t expect the crash of 2011 in kokanee numbers in Wood Lake will bounce back until at least 2016.
Acoustic trawls show there are lots of juvenile fish in the lake, which is encouraging, he said.
The ministry is keeping an eye on water levels in Middle Vernon Creek and the District of Lake Country is cooperating by increasing flows in the creek during the spawning period, he said.
And, further north in the valley, Kalamalka Lake had a high number of shore-spawning kokanee return to lay eggs this fall, he noted.