Study of Oyster Growth and Population Structures of the Public Reefs in Matagorda, East Matagorda, Tres Palacios and Lavaca Bays - Survey of Oyster Populations and Associated Organisms

There were two distinct peaks of oyster spat (Crassostrea virginica) setting on the three reefs sampled in 1964. The first occurred in late May and early June with the second and smaller peak occurring in October. All three reefs sustained heavy mortalities in 1964, beginning in August on Gadwall and Middle Ground reefs and in December on Sand Point Reef. The cause of the Gadwall and Sand Point mortalities was unknown. Data obtained to determine the incidence of Dermocystidium marinum on each reef indicated this organism was a causative agent of the Middle Ground mortalities. Studies made to determine the growth rates of commercial and Gulf oyster populations in the Matagorda Bay area indicated that the average growth rate of commercial oysters varied between ,08 mm per day and .23 mm per day while that of Gulf oysters ranged from .09 mm per day to .10 mm per day. Oyster production in the Matagorda Bay area in 1963-1964 was very low with only 12 per cent of the oysters handled by local plants coming from waters in this area.