The San Pedro (also known as the Pacific beakfish) Oplegnathus insignis is a species of perciform fish found in the eastern Pacific Ocean. In northern Chile, San Pedro are an important food fish currently being evaluated for aquaculture. The purpose of this study was to conduct an initial evaluation of the cortisol stress response in captive‐bred San Pedro. The fish were subjected to confinement stress by crowding them into a low volume of water (231 kg/m3) for 90 min. Blood was collected over time for the determination of plasma cortisol. Confinement resulted in a significant increase in plasma cortisol, from a resting concentration of 24.9 ng/mL to 120.7 ng/mL after 10 min into the stress experience. After 20 and 60 min of stress, cortisol concentrations plateaued at 225.3 ng/mL and 243.7 ng/mL, respectively, followed by a decrease to 56.1 ng/mL by 90 min. These results indicate a rapid and robust cortisol stress response in this species. This is the first evaluation of the San Pedro stress response, and these data will serve as the baseline for future evaluations of San Pedro stress physiology and the development of aquaculture techniques suitable for this species.

Aplicación de estrategias nutricionales y su efecto en el crecimiento en el cultivo continuo de Spirulina (Arthrospira platensis) RESUMEN. Se realizó un cultivo continuo de Spirulina (Arthrospira platensis) durante 78 días en un fotobiorreactor tubular de 300 L de volumen. Durante este periodo se registró el crecimiento en biomasa y la respuesta del cultivo a la estrategia de adición del medio nutritivo. Utilizando como base el medio Zarrouk modificado, se elaboraron tres medios: medio inicial (MI), medio crecimiento (SA1+SA2) y medio mantenimiento (SB1+SB2) para las distintas etapas del cultivo. La entrega de los medios se efectuó paulatinamente y de acuerdo a los requerimientos del crecimiento en biomasa (en peso seco) diario del cultivo. La biomasa inicial del cultivo fue de 2,0 g L -1, al día 20 se efectuó la primera cosecha parcial (50%) dando inicio a una nueva etapa del cultivo con una biomasa inicial de 1,7 g L -1 , 20 días después se realizó una segunda cosecha parcial del cultivo, iniciando una tercera etapa de cultivo con una biomasa de 1,6 g L -1 . Los resultados obtenidos al cabo de las cosechas fueron, en promedio, de 3,7; 4,1 y 9,7 g L -1 , respectivamente. El análisis proximal efectuado al final del cultivo continuo indicó un 71,6% de proteína. Palabras clave: Arthrospira platensis, Spirulina, medio nutritivo, crecimiento, cultivo, Chile. Application of nutritional strategies and their effect in continuous culture of Spirulina (Arthrospira platensis)ABSTRACT. A continuous culture of Spirulina (Arthrospira platensis) was performed for 78 in a tubular photobioreactor of 300 L volume. During this period there was growth in biomass and crop response to the strategy of adding the nutrient medium. Using as a basis the modified Zarrouk medium, three nutritive combinations were elaborated: initial medium (MI), growth medium (SA1+SA2) and maintenance medium (SB1+SB2) for different crop stages. The media delivery is affected gradually and in accordance with requirements of growing biomass (dry weight) daily cultivation. The initial crop biomass was 2.0 g L -1, on day 20 of culture was made the first partial harvest (50%) starting a new stage of the crop with an initial biomass of 1.7 g L -1, 20 days after a second crop was partially culture initiating a third culture step with a biomass of 1.6 g L -1 . The results obtained after harvest were, on the average, 3.7; 4.1 and 9.7 g L -1 respectively. The proximal analysis was performed at the end of the continuous cultivation showed a 71.6% of protein content. Keywords: Arthrospira platensis, Spirulina, nutrient medium, growth, culture, Chile. ___________________Corresponding author: Elizabet Rojas (elizabet.rojas@cordunap.cl) INTRODUCCIÓNLa especie Arthrospira platensis, conocida como Spirulina, es una cianobacteria, capaz de convertir la energía del sol en compuestos químicos usando dióxido de carbono y liberando oxígeno. Por sus características, ha adquirido gran importancia en la industria de alimentos, farmacéutica y cosmética, debido a su alto valor nutri...