The impact of illegal fishing on efficacy of bycatch mitigation for wandering albatrosses

Incidental mortality of non-target species in fisheries (bycatch) is driving population declines of seabirds globally. For wandering albatross Diomedea exulans populations in the Southern Ocean, current fisheries threats are primarily from pelagic longline operations, and to a lesser extent demersal longline and trawl fisheries. Mitigation methods including night setting, bird-scaring (tori or streamer) lines and branch line weighting, have been implemented successfully in some fisheries. For example, mitigation combined with fisheries closures during the breeding season have reduced seabird bycatch in CCAMLR demersal longline fisheries to negligible levels). However, bycatch remains high in pelagic longline fisheries for tuna and billfish, because mitigation regulations mandated by tuna regional fisheries management organizations (RFMOs) are not best practice, and observer coverage and compliance are poor, all of which limit the ability to quantify and mitigate mortality. While many of these fisheries with current high levels of bycatch lie outside the CCAMLR management area, they impact bird species that occupy waters within the region, and thus are of interest, as is understanding population recovery from past bycatch mortalities within CCAMLR fisheries. Difficulties in disentangling the relative impacts of different fisheries on albatross populations are compounded by illegal, unregulated, and unreported (IUU) fishing. It can be assumed that IUU vessels do not use bycatch mitigation measures and so bycatch rates are likely to be high in areas of high overlap between birds and fisheries; however, the cryptic nature of these operations make this difficult to test empirically. Although breeding populations of wandering albatross in the Indian Ocean have recovered from previous bycatch-driven declines, the well-studied breeding population at Bird Island (CCAMLR Area 48.3), continues to decline steeply due to a combination of climate and fisheries mortality. Given uncertainties in the scale and impacts of both regulated and IUU fishing, it is important for managers to better predict the effect of existing and additional management actions on albatross populations. Here, we simulated growth rates of the Bird Island wandering albatross population under different management scenarios to determine if improvements in bycatch mitigation in regulated fisheries would be sufficient to allow the population to recover, or whether recovery would also require reductions in IUU fishing. In this paper, we introduce the goals and methods of this study, present preliminary results, and describe planned future work.