Peña, R., I., Moguel-Hernandez, G.M., Haro-Ballesteros, M., Contreras-Olguín, S., Dumas & L.G., Flores-Montijo (2022). Effects of starvation and point of no return during the early development of the Pacific red snapper Lutjanus peru. Aquaculture 2022. San Diego, Estados Unidos de América, febrero 28 - marzo 4, 2022, 1.
Renato Peña 1, Ivette Moguel-Hernandez 2, Gretchen Mariana Haro-Ballesteros 2, Mauricio Contreras-Olguín 1, Silvie Dumas 1 y Laura Guadalupe Flores-Montijo 1
The larval period is a critical phase in fish development where larvae are particularly vulnerable to starvation and predation which are the main regulators of larval survival. Particularly at the onset of the exogenous feeding after yolk exhaustion when larvae must start feeding on their own. If no food is available, starvation may induce severe behavioural, developmental and nutritional problems, leading to a deterioration point known as the point of no return (PNR) in which the larvae will no recover even when food is present and dead is imminent. The time to reach the PNR isspecies-specific. In culture conditions, the determination of the PNR and the evaluation and description of the effects of early starvation can be a valuable tool to identify larvae with starvation symptoms and it could also be useful in the evaluation of new or different culture conditions or prey types. Hence, the objective of the present study was to establish the PNR and to use different methods to evaluate and characterize the effects of starvation at the time of first feeding of Pacific red snapper Lutjanus peru larvae.
To study the effect of starvation on the early development of Pacific red snapper, mature wild-captured L. peru brood stock were hormonally induced to spawn in the laboratory. The viable eggs were placed in a 100L cylinder-conical white tank for incubation. Larvae were randomly sampled directly from the incubation tank at 0 (hatching), 24, 48, 72,96 and 120 hours after hatching (ha h). The PNR was estimated using the feeding incidence as reference. Different body proportions were measured in sampled larvae and histological analysis was performed. Biochemical analyses included the estimation of the digestive enzymatic activity (trypsin, cathepsin-like, amylase and lipase), and the concentration of proteins and free amino acids(FAA).
The first 48 ha h were characterized by an active differentiation and growth which corresponded to the yolk-sac stage. The PNR occurred between 96 and 120 ha h when the feeding incidence was less than half of the maximum incidence registered. After the exhaustion of the yolk sac and oil globule, steady degradation of the larval body was evident since all body segments decreased until the end of the study. The digestive tract reflected the effects of starvation by a gradual shrinkage of the enterocytes of theanterior and posterior intestines. Furthermore, the digestive enzymaticactivity diminished during the starvation period compromising the digestive andabsorptive capacity of the larvae. The free amino acids showed importantfluctuation during the starvation period although the total concentration of FAA increased at 120 hah.
The results suggest that the morphometric and histological features of the larvae could be a useful indicator of their starved condition under culture conditions. Further studies are required to evaluate the recovery capacity of the larvae to early starvation.
Palabras clave: development; starvation; Ltjanus peru; point of no return
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