Webb: FISH POPULATIONS OF THE AVON-H . . .

New Zealand Journal of Marine and Freshwater Research abstracts

FISH POPULATIONS OF THE AVON-HEATHCOTE ESTUARY 1. GENERAL ECOLOGY, DISTRIBUTION, AND LENGTH-FREQUENCY

B. F. Webb

Zoology Department, University of Canterbury, Christchurch, New Zealand

Abstract Characteristic organisms are tabulated, and the substrate conditions briefly described for seven habitats in the Avon-Heathcote Estuary, Christchurch, New Zealand. Temperatures and water movements within the estuary are outlined. From April 1965 to April 1966, samples were collected by short otter-trawl shots, gill netting, beach seine hauls, and dip netting; the limitations of the gear are noted. The distributions and movements are recorded for nine fish species: sand flounder, Rhombosolea plebeia (Richardson); yellow-bellied flounder, Rhombosolea leporina (Hutton); common sole, Peltorhamphus novae-zeelandiae (Gunther); ye'llow-eyed mullet Aldrichetta forsteri (Cuvier and Valenciennes); kahawai, Arripis trutta (Bloch and Schneider); spotty, Pseudolabrus celidotus (Bloch and Schneider); cockabully, Tripterygion nigripenne (Cuvier and Valenciennes); common bully, Gobiomorphus basalis (Gray); and globe fish, Spheroides richei (Freminville). Length-frequency distributions showed that most of the nine species of fish used the estuary as a feeding area for adults and as a nursery area. Only two species did not migrate to and from the sea. Length-weight relationships for eight species showed that weight was a function of length approximately cubed, and that the exponential equation could be used to predict weight from length. Regressions of caudal fin length on standard length for four species gave a positive correlation (r = +0.95). Relative proportions of body length to caudal fin length were related to habitat; fish of benthic habits had proportionally shorter caudal fins than pelagic fish.

N.Z. Journal of Marine and Freshwater Research 6 (4): 570-601
(Received for publication 1 April 1968)

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