In an area that has barely been modified by fish aggregating devices (FADs) (e.g., the Mozambique Channel, known to be naturally enriched with logs, with few FADs), we found that the condition of skipjack tuna (Katsuwonus pelamis) associated with floating objects was lower than those in free-swimming schools. As this result was found in an area that mimics the environmental state prior to the use of FADs, it questions the interpretation of previous studies where such a difference has been interpreted to reflect the impact of extensive FAD deployment on tunas. It is possible that before the use of FADs, tunas associated with logs were also in poorer condition than tunas in free-swimming schools. Our results suggest that the evolutionary reason for which tunas associated with floating objects might not relate to short-term trophic benefit, and alternative hypotheses (e.g., the meeting point hypothesis) are discussed to explain this result.
Identification of skipjack tuna (Katsuwonus pelamis) pelagic hotspots applying a satellite remote sensing-driven analysis of ecological niche factors: A short-term run