Maturity and Fecundity of One-Year-Old English Native Oysters, O. edulis

Abstract

BY the courtesy of Major A. Gardner, one of us (J. H. O.) was able to study the spawning, spatfall and growth of the native oyster, O. edulis, on the Blackwater and Roach oyster beds in 1935 and 1936. The summer of 1935 resembled that of 1921 in being continuously warm, and also in yielding heavy falls of spat on the Blackwater. In 1922, one of a small sample of one-year old oysters obtained there experimentally was found at this extremely early age carrying larvæ¹. The prevalent notion is that English natives do not mature until they are three years old. In a lot of 104 selected well-grown 1935 spat from the Blackwater kindly supplied by Major Gardner on August 6, 1936, two were found with young, three were mature or nearly mature females and fourteen were ripe males. New evidence was therefore obtained of the possibility of English native oysters maturing as females and producing young at an age of a little more or less than one year after an exceptionally warm season.