The Mexican snook, Centropomus poeyi, supports an important fishery in southeastern Mexico. Due to its protandrous hermaphroditism, females may be especially sensitive to overfishing because they tend to be larger and selective removal has the potential to negatively affect natural populations, thus making urgent the need to contribute on management strategies for the species. The objective of this study was to produce batches of reproductive females at an early age and a small size by using 17β-estradiol (E2) in the diet. In two separate experiments, we fed fish 0, 10, 20, 30, 40, 50, or 60 mg of 17β-estradiol per kg of food for 60 days during gonadal differentiation. Fish fed with 50 and 60 mg of E2 per kg of food resulted in 100% feminization, while the control group (0 mg of E2) was 100% male. Three years after feminization, sex-reversed fish remained female, producing oocytes and were capable of spawning, while fish in the control group were ripe males with running milt. E2-treated groups were significantly larger (weight and length) than the control groups for up to six months after treatment, but the difference was undetectable at 300 days post-treatment. Survival was high in all treatments (100%). We obtained high percentages of functional females using dosages of 50 and 60 mg kg -1 of E2 for 60 days, with 80% of the induced fish spawning and producing fertilized eggs and larvae. The results obtained in this study provide opportunities for broodstock management and sex manipulation.

Las grasas y los lípidos se definen como compuestos químicos orgánicos solubles en solventes orgánicos. A diferencia de otros nutrientes, los lípidos no se mezclan con el agua, lo que provoca un proceso especial durante su digestión, absorción, transporte, almacenamiento y aprovechamiento. Dos décadas atrás, se descubrió que los lípidos son esenciales para el crecimiento y desarrollo normal tanto en animales como en humanos y cuando no hay suficiente en las dietas, se producen efectos negativos en los diversos procesos fisiológicos. Los ácidos grasos esenciales, después de que han sido ingeridos, se distribuyen entre las células del tejido graso, donde se almacenan y se incorporan con gran eficiencia a los tejidos del organismo. Evidencias epidemiológicas revelan que una dieta rica en ácidos grasos favorece una buena salud. En el presente manuscrito, presentamos la relevancia de estos nutrientes y su relación de estos en los peces y en la salud humana.

The zooplankton taxonomic group composition was analyzed in a known spawning area for snooks of the family Centropomidae during March 2011-February 2012 near the González River's mouth, a tributary of the Grijalva-Usumacinta River system, discharging into the southern Gulf of Mexico. Zooplankton was collected near the surface using three distinct zooplankton nets (20, 64, and 120 μm). Sixteen zooplankton taxonomic groups were collected between the three nets. Copepoda (76.9%), Trematoda (6.7%), Bivalvia (4.6%), and Chaetognatha (Sagittoidea 4.3%) numerically dominated zooplankton community structure. The 120 and 64 μm nets collected the highest diversity of zooplankton (15 taxa). Zooplankton was more abundant during June-October (summer storm season). They associated with lower salinities (due to the increase in the discharge volume of the Grijalva-Usumacinta River system) and higher regional primary productivity than observed during the rest of the year (March-May, dry season, and November-February, winter storm season). The highest peak of zooplankton abundance was found in November during the beginning of winter storms. Nine taxonomic groups were observed frequently and abundantly during the summer storm season, while only five taxonomic groups were abundant during the dry season.

Por su importancia económica y soporte de grandes pesquerías en el Golfo de México, se considera al robalo blanco como uno de los peces más importantes tanto para los pescadores ribereños como para los de aguas marinas, por ello la importancia de generar información para la reproducción de esta especie en condiciones de cautiverio, lo que permitirá no solo la repoblación de cuerpos de agua sino también su producción y engorda involucrando a los pescadores creando conciencia en la necesidad de producir para cosechar.

This study was carried out to identify the effects of salinity and temperature during Apocyclops panamensis culture, fed with Tetraselmis chuii. The experiment was conducted in laboratory conditions for 14 days. Nauplii from the same cohort were used to start the experiment, using a density of 1 ind mL−1 in a volume of 400 mL. The feed consisted of a daily supply of 20 000 cell mL−1 of microalgae. Nine treatments with three replicates were evaluated (24◦C-28h, 24◦C-32h, 24◦C-36h, 28◦C-28h, 28◦C-32h, 28◦C-36h, 32◦C-28h, 32◦C- 32h and 32◦C-36h). The factorial ANOVA indicates that temperature had a significant effect on the abundance of total copepods at day 14 (p = 0.02), while salinity did not show a significant effect (p = 0.06) on the total population of A. panamensis. Significant effects of temperature (p < 0.01) and salinity (p < 0.001) were observed for the nauplii population. The best growth of the entire population was reached in the treatment 32◦C-28h, with a population of 1 380.95 (± 1 267.06 ind L−1 (± 1 267.06) at the end of the experiment. Treatments 32◦C-28h and 32◦C-32h produced the highest average population of nauplii and copepodites at the end of the experiment. Adult females presented the greatest abundance in the 32◦C-32h treatment with 214.29 ind L−1, adult males increased between days 11 and 14 in treatments 24◦C-28h, 32◦C-28h, and 32◦C-32h without exceeding 170 ind L−1. In this study, it is evident that A. panamensis prefers warm temperatures and brackish environments.