The aim of the study was to evaluate the performance of Litopenaeus vannamei in an intensive photo-heterotrophic hypersaline system with minimal seawater replacement, and establish relationships between parameters of a stochastic production model and relevant water quality variables. Six experimental 1000 m 2 lined ponds were stocked at a density of 120 shrimp m À2 for a 105-day trial. Salinity increased from 37 to 45 AE 2 g/L, and the water level was maintained with the weekly addition of filtered seawater, equivalent to 1.6% per day. The stochastic model predicted that, at harvest, there is 95% confidence that the system produces between 12.1 and 14.7 t/ha with a mean final individual weight of 13.1 g and a mean survival of 84.2%. Sensitivity analyses showed that dissolved oxygen and individual final weight of shrimp were the main variables influencing yield variance.Nitrogenous compounds were maintained between optimal cultivation levels (NH 3 -NH 4 + = 0.73 AE 0.43 mg/L, N-NO 2 À = 0.09 AE 0.05 mg/L, N-NO 3 À = 3.22 AE 0.11 mg/L). Heterotrophic bacteria (6.6 AE 3.4 9 10 5 CFU/ml) and chlorophyll-a concentration (108.5 AE 80.2 lg/L) showed a similar development pattern, indicating a strong relationship between bacteria and microalgae during cultivation. Vibrio spp. concentrations were low (1.24 AE 1.42 9 10 3 CFU/ml). It was shown that the photo-heterotrophic system could be used in hypersaline conditions, typical of semi-arid regions, to consistently produce between 12.1 and 14.7 t/ha in 15 weeks. K E Y W O R D Shypersaline, intensive cultivation, Litopenaeus vannamei, minimal seawater replacement, photo-heterotrophic, stochastic modelling

ABSTRACT. The Pacific red snapper, Lutjanus peru, is a commercially important species throughout its distribution range, making it a good alternative for aquaculture; however, there is few information regarding environmental conditions and their influence on early development of this species. Temperature is one of the main factors affecting embryo and larval development in marine fishes. In this paper, the effects of different temperatures upon hatching rate, growth, consumption of yolk sac and oil droplet and the formation of the digestive system and eye pigmentation were evaluated in larvae of this species under experimental conditions. Eggs incubated between 20 and 32°C showed hatching rates higher than 90%. However, larvae maintained at 26°C showed significantly larger notochord length and were the first to complete the pigmentation of the eyes and the formation of the digestive system when still possessing enough reserves in the yolk sac. Therefore, according to the results obtained, it is recommended that the incubation of eggs and larval rearing in Pacific red snapper takes place between 25 and 26°C. Keywords: Lutjanus peru, temperature, larval development, hatching, survival, growth, aquaculture. Influencia de la temperatura sobre el desarrollo larval temprano del huachinango del Pacífico, Lutjanus peru (Nichols & Murphy, 1922)RESUMEN. El huachinango del Pacífico, Lutjanus peru, es una especie de importancia comercial a lo largo de su rango de distribución, lo cual lo hace un buen candidato para la acuicultura. Sin embargo, existe escasa información acerca de las condiciones ambientales y su influencia sobre el desarrollo temprano de esta especie. La temperatura es uno de los principales factores que afectan el desarrollo embrionario y larval en los peces marinos. En este trabajo se evaluaron los efectos de diferentes temperaturas sobre la tasa de eclosión, crecimiento, consumo del saco vitelino y de la gota lipídica, formación del sistema digestivo y pigmentación de los ojos en larvas de esta especie bajo condiciones experimentales. Los huevos incubados entre 20 y 32°C presentaron tasas de eclosión mayores al 90%. Sin embargo, las larvas mantenidas a 26°C presentaron una longitud notocordal significativamente mayor y fueron las primeras en completar la pigmentación de los ojos y la formación del sistema digestivo cuando aún poseían suficientes reservas en el saco vitelino. De acuerdo a los resultados obtenidos se recomienda que la incubación de huevos y la cría larval del huachinango del Pacífico se realice entre 25 y 26°C.

We use a bioeconomic approach to analyse the production, and economic performance of shrimp (Litopenaeus vannamei) reared in a photo-heterotrophic, hypersaline intensive system with minimal water replacement during spring-summer (SS) and summer-autumn (SA) production cycles in the semiarid region of Baja California Sur, Mexico. Salinity was maintained at 45 AE 2.0 (SS) and 46 AE 2.5 g L À1 (SA), dissolved oxygen at 4.8 AE 0.5 (SS) and 4.4 AE 0.4 mg L À1 (SA), pH at 7.9 AE 0.3 (SS) and 7.8 AE 0.2 (SA), and temperature at 28.4 AE 2.4 (SS) and 31.6 AE 0.7°C (SA). The bioeconomic analysis indicated that the mean production in SS is 13.2 t ha À1 , and that mean net revenues of 12 600 $USD ha À1 and a benefit-cost ratio of 1.31 could be obtained. For SA, mean production was 17.7 t ha À1 , and mean net revenue and the benefit-cost ratio were 38 930 $USD ha À1 and 1.93, respectively. The optimum harvesting times were at 90 (SS) and 92 days (SA) when the economic indicators and the confidence of obtaining them were maximized. Superior economic performance of SA was a consequence of faster shrimp growth and higher shrimp prices. More stable conditions of water quality resulted in better production in SA. A sensitivity analysis showed that shrimp price was the most important factor influencing net revenue, and that final weight of shrimp, dissolved oxygen and temperature had intermediate influence. Positive economic outcomes indicate the potential of the photoheterotrophic technology for shrimp production in semiarid regions.

Los mamíferos silvestres y otros grupos taxonómicos de importancia económica como por ejemplo ganado de engorda, aves de corral, peces y crustáceos, son propensos a desarrollar enfermedades de origen bacteriano que pueden diseminarse rápidamente.

Los carnívoros silvestres son propensos a infectarse de enfermedades altamente virulentas y mortales que pueden extinguir poblaciones completas. ¿Podrían herramientas como los biosensores con nanopartículas, ayudar a detectar las enfermedades de este grupo de manera rápida y en campo?