Feeding Cessation Improves Red Tide Resistance in Aquacultured Yellowtail

Le résumé fourni par la source

Red tides sometimes impact the aquaculture industry worldwide, resulting in mass fish mortalities. It is known empirically that their effects can be mitigated by cessation of feeding. However, specific methods to maximize this technique’s effectiveness and provide physiological support remain limited. In the present study, we investigated the effects of the feeding‐cessation period on a fish’s resistance to a harmful red‐tide microalga, the Chattonella marina complex (“ Chattonella ”), using yellowtail ( Seriola quinqueradiata ) of two ages and body weights: juveniles (74 days after hatching and ~15 g) and young (201 days after hatching and ~860 g). The fish mortality by Chattonella is thought to be associated with gill damage. Thereby, we measured oxygen consumption to consider plankton contact with the gills. Our results showed that feeding cessation for 4 or more days significantly increased survival, regardless of size. Body weight decreased with longer feeding cessation, but survival rates were not affected by body weight. To test red‐tide resistance, juvenile yellowtail were treated by feeding cessation for 1, 2, and 4 days, and young yellowtail for 1, 4, and 8 days. In the juveniles, a longer feeding pause also reduced oxygen consumption. Moreover, histological examination of the juveniles showed that a longer feeding pause reduced damage to the secondary lamellae of the gills. We propose that gill damage was mitigated by reducing the interaction between Chattonella cells and the gill lamellae, likely as a result of decreased oxygen consumption. These results indicate that feeding cessation for a specific period of time physiologically improves red‐tide resistance in yellowtail.

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