Low kokanee numbers prompt bull trout removal

Low kokanee numbers prompt bull trout removal

Posted on: July 18, 2018 1:00 pm

As part of the Kootenay Lake Action Plan to recover kokanee stocks, some bull trout will be removed from the Duncan River, below the Duncan Dam, this summer.

Other actions to recover kokanee stocks in Kootenay Lake include continued stocking of kokanee eggs, increasing angling opportunities for bull trout, and removing bull trout from the Kaslo/Keen and Hamill creeks in early fall. Removal of bull trout is a short-term strategy to improve kokanee recovery.

The locations for bull trout removal were chosen based on where there would be maximum benefit to kokanee recovery, and the least impact on overall bull trout populations. Captured bull trout will be frozen, and then provided to local food banks.

Bull trout and Gerrard rainbow trout prey on kokanee. Bull trout pose the bigger threat to kokanee. Bull trout spawning populations increased by more than 100% between 2015 and 2017, with approximately 3,500 bull trout spawners in 2017 alone.

The health of the Kootenay Lake Gerrard rainbow trout and bull trout depend on the health of kokanee populations. Modest removals of bull trout will help recover kokanee stocks, which will benefit both rainbow trout and bull trout in the long term.

Historically, the number of spawning kokanee in Kootenay Lake have ranged from 250,000 to nearly 2.2 million. This number declined to 18,000 in 2017. This decline has been caused by historically high kokanee predator abundance (bull trout and Gerrard rainbow trout). 

The ministry began stocking kokanee eggs in 2015. Since then, 16 million eggs have been stocked. There are plans to stock another five million to seven million eggs this fall.

Populations of the kokanee (spawners and in-lake abundance) and bull trout will be assessed this fall. Gerrard rainbow trout will be surveyed in the spring, to assess the impact on kokanee numbers.

The 2016 Kootenay Lake Action Plan was developed by an advisory team with representatives from the ministry, Freshwater Fisheries Society of B.C., the BC Wildlife Federation and First Nations. The advisory team recommended additional stocking and predator management in May 2018.

Learn More:

Kootenay Lake Action Plan: http://www.env.gov.bc.ca/kootenay/fsh/main/mainfish.htm

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