Satellite Telemetry in Marine Megafauna

Abstract

Satellite telemetry has transformed our understanding of marine megafauna movement ecology, revealing migratory routes, habitat preferences, and foraging strategies across oceanic scales that were previously inaccessible to conventional observation. This study synthesised satellite tracking data from 312 individuals across six marine megafauna taxa -- loggerhead sea turtles (Caretta caretta), fin whales (Balaenoptera physalus), whale sharks (Rhincodon typus), bluefin tuna (Thunnus thynnus), leatherback sea turtles (Dermochelys coriacea), and blue sharks (Prionace glauca) -- deployed across the North Atlantic and Mediterranean basin between 2018 and 2023, comprising 84,240 validated satellite positions and 12,840 dive profile records from PSAT (pop-up satellite archival tags) deployments. Mean track duration was 184 +/- 84 days across all taxa; longest individual tracks were recorded for leatherback turtles (mean 284 +/- 48 days). Kernel density estimation identified 18 high-use areas (50% kernel utilisation distributions) spanning pelagic, shelf-edge, and seamount habitats. Habitat selection modelling (MaxEnt and generalised additive models) identified sea surface temperature, chlorophyll-a concentration, and bathymetric gradient as the primary predictors of megafauna space use across taxa. Mean migratory distances ranged from 2,840 +/- 480 km (loggerhead turtles, Mediterranean-Atlantic) to 8,420 +/- 1,240 km (leatherback turtles, trans-Atlantic). Overlap analysis between megafauna utilisation distributions and active fishing effort (Global Fishing Watch) identified eight critical bycatch interaction zones with > 40% overlap between species core areas and longline fishing effort, providing spatially explicit targets for bycatch mitigation measures under the EU Common Fisheries Policy