Small brown shrimps Penaeus aztecus, were found at tertiary bay in April. Emigration began in June when the shrimp were about 81 mm long. A second wave was observed in August. Juvenile white shrimp, Penaeus setiferus,, appeared in the samples in early June, A second, but smaller, wave was observed in September. Shrimp caught in the 20-foot trawl samples were smaller than shrimp caught by commercial trawls. Thus data based on 20-foot trawl catches were considered invalid. The 1964 commercial brown shrimp catch, in the bay system increased 12 per cent over 1963. White shrimp landings increased. 60 per cent over 1963.