An unexploited population of oysters,Ostrea lutariahutton, from foveaux strait

Abstract

An unexploited population of Ostrea lutaria Hutton discovered off Ruapuke Island at the eastern end of Foveaux Strait in January 1965 is described, as are the bathymetry, approximate distribution of sediments, and current and temperature regimes of the area. Scuba divers found that oysters occurred in an elliptical area approximately 200 m by 900 m oriented in the direction of the main currents. The stock of oysters was estimated at three and one quarter million. At the longitudinal extremities of the population oysters occurred at low densities and were very unevenly dispersed. Elsewhere they were more evenly dispersed in the peripheral areas of low density than in the central zones of high density where their numbers varied greatly over very short distances. Oyster distribution was sharply delimited to the north‐east and south‐west where softer sediments occurred. A firm substrate of coarse pebble gravel with considerable quantities of interstitial sand was the base for the population. Spatfall intensity closely paralleled adult density and little spatfall was observed at any distance from stocks of adults.