Effects of cage aquaculture on native fish populations

Description

The purpose of this project is to evaluate the impacts of cage aquaculture on the resident fish populations of a cold-water lake. This research is being conducted at the Experimental Lakes Area (ELA) in association with an ecosystem-level study on the environmental effects of cage culture (ACRDP project CA-01-09-001). A small cage culture facility has been established in one lake at ELA and rainbow trout will be grown here over two open-water seasons (2003 and 2004) using current culture practices. The native fish populations in this lake were studied using mark-recapture methods to determine the effects of the culture operation on their abundance, survival, growth, and reproduction. These fish populations had been monitored for more than 10 years prior to this experiment. The behaviour of native lake trout and white sucker in the lake was monitored in 2003 using acoustic tags to determine changes in depth and location of fish after installation of the cage. Lake trout initially avoided the aquaculture pen after installation, but they reverted to their original movement patterns later in the year. There were no apparent effects of the cage culture operation on other aspects of lake trout biology. In contrast, smaller-bodied forage fishes appeared to be attracted to the net cage. Fish populations in nearby un-manipulated lakes were monitored in 2003 as controls for the experiment and these will be monitored again in 2004. This study is crucial to our understanding of how resident fish populations are affected by cage culture facilities, and the interaction of wild and farmed fish.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2002 - 2005

Ecoregion(s)

Central Canada: Lake Winnipeg, Nelson River Drainage Basin

Principal Investigator(s)

Ken Mills
Email: MillsK@dfo-mpo.gc.ca