GROWTH OF OYSTERS, O. VIRGINICA, DURING DIFFERENT MONTHS

Abstract

Observations made in Milford Harbor, Connecticut, showed that oysters, O. virginica. do not grow during the hibernation period. The growing period is of 8-months'' duration, from Apr. to Nov., both months inclusive. Tne increase in length was most rapid during May, June and July, representing 22.57, 19.03 and 22.12%, respectively, of the total annual increment. The growth in width was especially rapid in June and the increase in greatest depth was not appreciable until July. The increase in volume continued from Apr. through Nov.; the greatest monthly increases were recorded during Aug. and Sept.; these 2 months combined gave approx. 55% of the annual increase in volume. Increase in size was most common during July and Aug. when almost all the oysters showed it, and least common in Apr. and Nov. Neither the process of gametogenesis nor spawning of oysters interfered with the growth of the shell, at least as far as increase in length and width was concerned. The chief increase in length and width took place during the 1st half of the growing period, while the increase in depth and volume was most pronounced during the 2d half. Laboratory expts. in which groups of oysters were kept simultaneously in running water of 10[degree], 15[degree], 20[degree] or 25 [degree]C grew fastest at 15", while the 20[degree] group was next. The optimum temp. range for their growth is either confined between these 2 temps. or, more probably, extends a degree or two outside these two limits giving a range from approx. 13[degree] to 22[degree]C.