Penaeus aztecus, brown shrimp, arrived at the tertiary bays in early April, but grew slowly. In May growth accelerated and emigration from the bay began in June when the shrimp were less than 90 mm long. A second wave of brown shrimp arrived in August. White shrimp, P. setiferus, arrived at the tertiary bays in June. This group of shrimp was followed by two smaller groups in August and October. Brown shrimp were found in Sabine Lake in May. The 1964 white shrimp were found in mid-June. In the fall a second wave of white shrimp was observed. Commercial brown shrimp landings reached a peak in July and August, but fell sharply after September. White shrimp production was high.