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Effects of triploid grass carp on aquatic plants, water quality, and public satisfaction in Washington State

North American Journal of Fisheries Management

By:
, , and
DOI: 10.1577/1548-8675(2002)022<0096:EOTGCO>2.0.CO;2

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Abstract

We investigated effects of triploid grass carp Ctenopharyngodon idella on aquatic macrophyte communities, water quality, and public satisfaction for 98 lakes and ponds in Washington State stocked with grass carp between 1990 and 1995. Grass carp had few noticeable effects on macrophyte communities until 19 months following stocking. After 19 months, submersed macrophytes were either completely eradicated (39% of the lakes) or not controlled (42% of the lakes) in most lakes. Intermediate control of submersed macrophytes occurred in 18% of lakes at a median stocking rate of 24 fish per vegetated surface acre. Most of the landowners interviewed (83%) were satisfied with the results of introducing grass carp. For sites where all submersed macrophytes were eradicated, average turbidity was higher (11 nephelometric turbidity units, NTU) than at sites where macrophytes were controlled to intermediate levels (4 NTU) or unaffected by grass carp grazing (5 NTU). Chlorophyll a was not significantly different between levels of macrophyte control; therefore, we concluded that most of this turbidity was abiotic and not algal. Triploid grass carp were a popular control option and effectively grazed most submersed macrophytes in Washington State. However, calculating stocking rates based on landowner estimates of aquatic plant coverage rarely resulted in intermediate levels of aquatic plant control. Additionally, the effects of particular stocking rates varied considerably. We recommend against using grass carp in Washington lakes where eradication of submersed vegetation cannot be tolerated.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Effects of triploid grass carp on aquatic plants, water quality, and public satisfaction in Washington State
Series title:
North American Journal of Fisheries Management
DOI:
10.1577/1548-8675(2002)022<0096:EOTGCO>2.0.CO;2
Volume
22
Issue:
1
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Fisheries Management
First page:
96
Last page:
105