Study of the bay populations of juvenile shrimp, Penaeus aztecus, Penaeus setiferus. Period covered: January 1, 1961 - December 31, 1961

This report is based on a total of 542 samples, 29063 brown shrimp and 14,569 white shrimp. Semi-monthly sampling of juvenile shrimp in Texas bays in 1961 confirmed that there are at least three waves of juvenile brown shrimp, Penaeus aztecus, and white shrimp, Penaeus setiferus, entering bay nursery habitats. The greatest abundance of juvenile browns occurred in May and June, whereas juvenile whites were present in fair numbers from July through December. Growth rates during July and August were highest for both species, with that for browns computed up to 1.5 mm per day and that for whites up to 1.8 mm per day. A sharp drop in abundance of both species in the bay this year was reflected later in almost direct proportion to the Gulf commercial catch. Bay environmental conditions possibly affecting abundance of at least the brown shrimp include higher river runoff, lower bay salinities, and lower bay water temperatures at a time when most of the larval browns were entering nursery areas. It is more probable, however, that some adverse condition in the Gulf was the main cause of the poor shrimp production of 1961. It was again found that in many shallow, tertiary bays and bayous shrimp do not reach the proper size for harvesting