Penaeid Shrimp Monitoring off the Central Texas Coast, 1977-1981

From October 1977 through March 1981 the Texas Parks and Wildlife Department's (TPWD) research vessel Western Gulf took 256 trawl samples in the Gulf of Mexico as part of a continuing program to monitor commercial penaeid shrimp stocks for movement, size and abundance. Night samples were collected off the central Texas coast during May-August at depths of 11-18, 20-27, 29-37 and 38-46 m. An additional transect out to a depth of 55 m was added in 1980 off the south Texas coast. Day samples were collected from 5-9, 11-18 and 20-27 m depth zones off Port Aransas and Pass Cavallo from October 1977 through March 1978 with supplementary samples from April 1978 to March 1981. There was no indication of a major movement of brown shrimp (Penaeus aztecus) into the Gulf before the closed season in 1978, 1979 or 1980. During 1978 and 1980 emigrating brown shrimp were most abundant in the 11-18 m depth zone in June corresponding with the start of the 1 June - 15 July Gulf closed season in Texas waters. Limited sampling during 1979 indicated that brown shrimp abundance was below average in all zones until August. Texas shrimp landings and TPWD shrimp samples were highest during 1978 and lowest during 1979. The mean size of brown shrimp generally increased with depth and all shrimp caught beyong 18 m met legal count (39/lb, heads-on) by August. During 1980 brown shrimp were more abundant during May off south Texas (346/h) than off central Texas (16/h). Catch rates were generally high (1654-2868/h) in the 11-18 m zone in both areas from June through August. White shrimp (P. setiferus) were most abundant during November and December. The mean sizes were smalled during December and January corresponding with the winter (15 December - 1 February) closed season.