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Neuroendocrine mechanisms involved in crustacean stress response are different and less understood than those of vertebrates. Although indirect evidence suggests the participation of catecholamines (CA), few studies have analyzed their levels during stress response in crustaceans. This study examined CA levels in hemolymph and tissue of whiteleg shrimp Penaeus vannamei besides other biochemical indicators in response to hypoxia (0.8-1.0 mg L -1 ). Shrimp were stressed by hypoxia exposure, and their responses were analyzed at several intervals (10-480 min). Hemolymph glucose levels decreased gradually due to a higher demand not compensated by the gluconeogenesis process from hepatopancreas or muscle after 10 min. Lactate levels in hemolymph showed a 5-fold increase after 10 min, and a correlation with CA levels in hemolymph was observed suggesting its possible role in signaling catecholaminergic activation from eyestalk in a period from 10 to 120 min. Protein levels in muscle and hepatopancreas increased gradually throughout the trial indicating the possible use of another energetic substrate as arginine phosphate. A decrease in triacylglyceride levels denotes its preferential utilization as an immediate energy source in the scape response during the first minutes of hypoxia exposure. Heart adrenaline and noradrenaline levels increased rapidly at the beginning of the trial showing a correlation with the use of triacylglycerides and carbohydrates in hepatopancreas and muscle (r = 0.89 and r = 0.93, P ˂ 0.05, respectively). This manuscript reports evidence of CA participation in response to stress due to hypoxia and discusses possible adaptation mechanisms.

This study compared survival, growth, feed conversion rate (FCR) and harvested biomass of two commercial strains of tilapia (Oreochromis niloticus) cultivated in Mexico: Spring Genetic-Benchmark Holding® originated from the Genetically Improved Farmed Tilapia GIFT (Genebank: GIFT GU477624.1) and strain B from different line-breeding (Genebank: Philippines GU477626.1, Guangdong GU477627.1, and America GU477628.1). The study was performed in six geomembrane ponds (2,520 m 3 ; 30×40×1.5 m) with supplementary aeration, in Los Pozos farm, El Rosario, Sinaloa, Mexico. In July 2016, 26,762 ± 170 fries of each strain (2.9 ± 0.1 g and 5.4 ± 0.2 cm) were cultivated in the nursery under similar conditions in triplicate at 11 ind m-3 for 34 days; then, they were transferred to the grow-out ponds and fed with 30% crude protein balanced feed (Purina®) at a rate of 12% live weight day-1 in three rations (07:00, 12:00 and 17:00 h) for 123 days. The results showed that Spring had a lower variation coefficient (VC) and higher survival, growth rate in weight, initial and final size, and harvested biomass. Survival was 30.7% greater in Spring and doubled harvested biomass (Spring 10 ± 0.8 t ha-1 vs. B strain 5 ± 4.7 t ha-1). Sixty percent of the Spring population reached a commercial weight of 500 g in day 123th of cultivation compared with 20% of B population in the same period. Except for FCR, VC was lower in the Spring strain. Differences in productive parameters were probably due to the genetic selection programs at which both strains were subjected.

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