Delta Marsh is a 19,000 hectare coastal wetland along the southern shore of Lake Manitoba, north of Portage La Prairie. It is one of the largest, most well-known freshwater coastal wetlands in North America.
However, since 1982, habitat conditions in the marsh have deteriorated, resulting in decreased use of the marsh by wildlife, particularly breeding and staging waterfowl.
The common carp is believed to be responsible for most of the damage to the marsh. Carp are large, vigorous, bottom-dwelling fish that stir up bottom sediments and uproot aquatic vegetation. This leads to poor water quality and major loss of aquatic plant life, making the area less suitable for other fish and wildlife.
In 2008, a working group of conservation and research organizations was asked to design a project that would exclude carp from the marsh. The solution they came up with was the use of exclusion structures, which are screens placed in select locations to prevent carp from re-entering the marsh.
Each fall, carp migrate to Lake Manitoba, returning to Delta Marsh to spawn in the spring. By installing the screens from approximately mid-May to late August, the carp’s journey is interrupted, and they are prevented from re-entering the marsh. Due to their large size, carp cannot pass through the screens.
Six exclusion structures are currently in use, protecting approximately two-thirds of the marsh. With fewer carp in the marsh, water quality has improved, allowing re-growth of submersed and emergent vegetation. This is bringing back more wildlife, protecting shorelines from erosion, and benefitting the entire wetland ecosystem. View map of exclusion structures.