Tracking juveniles confirms fisheries-bycatch hotspot for an endangered albatross

Fisheries bycatch is a major threat to marine megafauna such as seabirds. Population monitoring has revealed low survival of juvenile seabirds over recent decades, potentially because naïve individuals are more susceptible to bycatch than adults. However, major gaps remain in our knowledge of behavior and interaction of juveniles with fisheries. Here, we tracked juvenile grey-headed albatrosses (Thalassarche chrysostoma) from South Georgia - the largest global population of this endangered species, and in rapid decline - to investigate their at-sea distribution and assess bycatch risk. Fledged juveniles dispersed to the northeast, overlapping with a bycatch hotspot for grey-headed albatrosses reported by the Japanese pelagic longline fleet in the southeast Atlantic Ocean. Given adult grey-headed albatrosses use regions less exposed to fishing activity (< 40°S), the majority of birds bycaught in this area are probably juveniles, and possibly immatures, from South Georgia, likely representing a key factor explaining the sustained population decline. Our study highlights the urgent need to uncover the ‘lost-years’ for marine megafauna to enable focused conservation efforts.

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