Movement ecology of a deep-pelagic mesopredator, the bigscale pomfret: implications for pelagic food web connectivity and fishery susceptibility

Abstract

The bigscale pomfret Taractichthys longipinnis is assumed to be a deep-pelagic fish that occurs primarily below 200 m but above the seafloor during the daytime. However, the lack of movement data for this and related species precludes precise ecological classification. Here, we used satellite telemetry to overcome historical methodological limitations to studying deep- pelagic fishes and enable direct characterization of the movement ecology of this large teleost. Time–depth data from pop-up satellite archival transmitting tags unambiguously identified bigscale pomfret as a deep-pelagic species that occupies the ocean twilight zone, with all individuals consistently undergoing diel vertical migration on a daily basis. Tagged pomfret exhibited biome-specific degrees of adherence to a light comfort zone during these vertical movements, ranging hundreds of meters, resulting in marked changes in vertical habitat use when crossing from the Slope Sea into the oligotrophic Sargasso Sea, where there is increased light penetration. This biome-level variation in the observed niche of bigscale pomfret highlights the role of water optical clarity in potentially restructuring pelagic food web interactions and modulating fishery bycatch risk.

Keywords:
Bramidae · DVM · Deep scattering layer · Lamnid shark · Mesopelagic · Micronekton · Midwater · PSAT

Publication Date
September 2025

PUBLICATION AVAILABLE AT:

https://doi.org/10.3354/meps14934