Preferences of Grass Carp for Macrophytes in Iberian Drainage Channels

Grass carp, Ctenopharyngodon idella, feeding preferences were studied from the age of 0+ to the age of 2+, in tank and pond conditions, by using combinations of macrophytes occurring as typical weed assemblages in Iberian drainage channels. The exotic species waterhyacinth and parrotfeather are the...

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Bibliographic Details
Published in:Journal of aquatic plant management 1997-07, Vol.35, p.79-83
Main Authors: Catarino, L F, Ferreira, M T, Moreira, I S
Format: Article
Language:English
Subjects:
Azolla filiculoides
Ctenopharyngodon idella
Lemna
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Summary:Grass carp, Ctenopharyngodon idella, feeding preferences were studied from the age of 0+ to the age of 2+, in tank and pond conditions, by using combinations of macrophytes occurring as typical weed assemblages in Iberian drainage channels. The exotic species waterhyacinth and parrotfeather are the most common and troublesome. Ivlev's index showed that two flotant soft-tissue species, Azolla filiculoides and Lemna sp., were clearly preferred by grass carp, whilst other species such as Potamogeton pectinatus and Myriophyllum spicatum were moderately eaten; and parrotfeather and waterhyacinth were avoided up to the age of 2+, and then only moderately eaten, as long as no preferred species were present. Selectivity decreased with carp age. Daily consumption rates of the two exotics were low, up to 25% of body weight. Preference indexes were found to be a useful tool to assess resource preference and make a preliminary evaluation of the efficacy and environmental impact of grass carp introduction on a new habitat/region.
ISSN:0146-6623