New Zealand Journal of Marine and Freshwater Research abstracts
Mouth gape, food size, and diet of the common smelt Retropinna
retropinna (Richardson) in the Waikato River system, North Island,
New Zealand
JACQUES A. T. BOUBEE
National Institute of Water & Atmospheric
Research Ltd
P.O.Box 11 115
Hamilton, New Zealand
FREDRICK J. WARD
Department of Zoology
University of Manitoba
Winnipeg, Manitoba, R3T 2N2, Canada
Abstract The feeding ecology of the common smelt, Retropinna retropinna, was
determined at several locations on the Waikato River system. The mean size
of the dominant prey was found to increase as smelt mouth gape increased. Smelt
smaller than 40 mm total length fed mostly on zooplankton. Chironomid larvae,
pupae, and adults were the dominant foods of larger fish from most sites, although
mysids and amphipods were the major prey in Lake Waahi and the Waikato River
estuary. Algae were the dominant food in many smelt but ingestion was probably
incidental. Seasonal and annual differences in dominant foods were minor. Common
smelt are generalists, capable of feeding on the majority of smaller organisms
present in their different environments; however, they may grow faster and
achieve a larger adult size when food of optimal size and nutritive value is
present.
Keywords New Zealand; Waikato River; fish; smelt; Retropinna retropinna;
feeding; mouth gape
New Zealand Journal of Marine and Freshwater Research, 1997, Vol. 31,
147-154
0028-8330/97/3102-0147 $7.00/0 (c) The Royal Society of New Zealand
1997
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