Tufted Duck (Aythya fuligula) habitat use and brood survival increases after fish removal from gravel pit lakes.

Abstract

This paper reviews research results on food competition between a freshwater fish community and a breeding Tufted duck population. After the experimental removal of fish from the Main Lake, the following effects were observed:
1. Invertebrate (chironomid and gastropod) food for ducklings and adult Tufted ducks increased substantially.
2. Tufted duckling brood use of the lake increased greatly and Tufted duckling survival appears to have increased.
3. Shoveler and Pochard nested successfully for the first time.
4. Submerged aquatic macrophytes grew profusely over the lake bed for the first time leading directly to large increases in use of the Lake by wintering herbivorous waterfowl.
5. When fish were re-introduced to the Main Lake sampling bay the increases in invertebrate abundance and, to a less marked extent, macrophyte abundance were reversed.
Fish removal is advocated as a potentially potent form of habitat management for waterfowl conservation areas.