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CA-01-09-001
Ecosystem experiment to assess environmental impacts of freshwater cage
aquaculture
Cage-reared rainbow trout accounts for most of the freshwater
aquaculture production in central Canada. Public concern over potential
environmental effects is currently limiting the expansion of this
industry. In particular, it is believed that organic wastes from cage
farms may contribute to increased nutrient concentrations, increased algae
growth, and reduced oxygen concentrations in fresh waters. The purpose of
this project is to identify and quantify the environmental effects of
rainbow trout cage culture on a lake ecosystem. This research is being
conducted at the Experimental Lakes Area (ELA) in northwestern Ontario. A
small cage culture facility has been established in one lake at ELA.
Rainbow trout fingerlings were stocked here, raised to market size, and
harvested (10 tonnes of fish produced) during the 2003 open-water season
using current culture practices. This will be repeated for at least one
more year. Water quality, sediment quality, algae growth, and invertebrate
communities are all being monitored in this lake and in a nearby reference
lake in the year before, and during the operation of this fish culture
facility. To date, we have not detected any substantial changes in
environmental quality since fish culture began in the lake. Solid waste
(manure and excess food) has settled in a very localized area immediately
beneath the cage. Dissolved nutrient concentrations, dissolved oxygen
levels and algae growth in the lake are similar to pre-farming conditions.
However, it is important to continue monitoring environmental quality to
determine if significant effects arise over time with increased waste
inputs. This research will provide a clearer assessment of the
environmental effects of cage culture in fresh water.
Project Start Date: February 1, 2002
Project Completion Date: March 31, 2005
For further information please contact: DFO project leader: Cheryl Podemski
(E-mail: PodemskiC@dfo-mpo.gc.ca) or Regional ACRDP Coordinator: Doug
Geiling (E-mail: geilingd@dfo-mpo.gc.ca).
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