Jat. Boubee et Fj. Ward, MOUTH GAPE, FOOD SIZE, AND DIET OF THE COMMON SMELT RETROPINNA-RETROPINNA (RICHARDSON) IN THE WAIKATO RIVER SYSTEM, NORTH-ISLAND, NEW-ZEALAND, New Zealand Journal of Marine and Freshwater Research, 31(2), 1997, pp. 147-154
The feeding ecology of the common smelt, Retropinna retropinna, was de
termined at several locations on the Waikato River system. The mean si
ze of the dominant prey was found to increase as smelt mouth gape incr
eased. Smelt smaller than 40 mm total length fed mostly on zooplankton
. Chironomid larvae, pupae, and adults were the dominant foods of larg
er fish from most sites, although mysids and amphipods were the major
prey in Lake Waahi and the Waikato River estuary. Algae were the domin
ant food in many smelt but ingestion was probably incidental. Seasonal
and annual differences in dominant foods were minor. Common smelt an
generalists, capable of feeding on the majority of smaller organisms p
resent in their different environments; however, they may grow faster
and achieve a larger adult size when food of optimal size and nutritiv
e value is present.