Size, sex and gonadic development of Litopenaeus vannamei (Crustacea: Decapoda: Penaeidae), during the closed season of 1999 in the Gulf of Tehuantepec, Mexico

Information of structure by size and sex as well as of the gonadic development of the white shrimp population Litopenaeus vannamei, obtained through fishing surveys during the shrimp closed season (June to August) of 1999 in the coastal zone of the Gulf of Tehuantepec, Mexico, is analyzed. The accumulated sample was of 7 815 organisms whose lengths were distributed in intervals of 80 to 220 mm of total length. Females were 60.6% of the population, while males 39.4%. Values of sexual proportion decreased gradually from sub-zone 91 (2.6:1 female/male) located in front of the port of Salina Cruz, Oaxaca, toward sub-zone 95 (1.2:1 female/male) in front of Puerto Chiapas, Chiapas, Mexico. The highest percentage of females in stage III or mature (21.6%) and in stage IV or spawned (34.5%) were observed in June, comparing sub zones, while at sub-zone 95 higher percentage of spawned females (p>0.05) were observed, therefore it is inferred that spawning process occurs with high intensity at this sub-zone, located Southeast of the Gulf of Tehuantepec, in Chiapas continental shelf. Population exhibit a differentiated size structure in the prospected area, locating smaller sized organisms at sub-zone 91 and adults at sub-zone 95.