Fine-scale behaviour and population estimates of endangered sooty albatross suggest low exposure (while not excluding high sensitivity) to bycatch

Recent developments in assessing species-specific seabird bycatch risks have demonstrated that fine-scale approaches are essential tools to quantify interactions with fishing vessels and to understand attraction and attendance behaviours. Matching boat movement with bird tracking data specifically allows us to investigate seabird-fisheries interactions for cryptic species for which on-board information is critically lacking. The sooty albatross Phoebetria fusca overlaps with fisheries throughout its range and is known to be vulnerable to incidental bycatch. Combining radar detectors, GPS and behavioural data from individuals from the Crozet Islands and boat locations during the incubation period, we investigated interactions of sooty albatrosses with fisheries in the southern Indian Ocean. Individuals foraged mostly in sub-tropical international waters, where they only encountered a small number of boats, all reporting to the Automatic Identification System (AIS). The low interaction rate during this period may suggest that sooty albatrosses are not strongly attracted to fishing vessels, and that attraction rates may vary between populations. However, this result should be interpreted with caution due to the low sample size and fishing effort during the study period, as these observations may conceal a higher bycatch risk during intense fishing effort and/or energetically demanding periods. The conservation status of this species requires further data to be collected throughout the annual cycle to provide an accurate assessment of the threat.