Trophic variation in the Southern hagfish Myxine australis under contrasting bottom- trawling scenarios

The trophic ecology of hagfishes remains one of the least understood among marine vertebrates, and the limited knowledge available has led them to be considered primarily scavengers. Consequently, an important role in the consumption of fisheries discards has been attributed to them. In this study, we analyzed, for the first time, the trophic ecology of a hagfish, Myxine australis , under contrasting bottom-trawling scenarios using gastrointestinal content analysis and stable isotope analysis of carbon and nitrogen. The results revealed a generalist and opportunistic feeding strategy based on the consumption of fish and invertebrates, with no evidence of ontogenetic changes in diet. The species also occupied a tertiary consumer position, with a marked dependence on benthic resources. In areas subjected to bottom trawling, the isotopic niche during the trawling period was approximately three times larger than that observed during the pre-trawling period. Differences in isotopic values and C:N ratios suggested periods of fasting followed by high food intake. Overall, these results indicate that M. australis exhibits trophic plasticity, shifting its feeding strategy according to resource availability, exploiting both natural resources and potential anthropogenic subsidies associated with fishing activity.