Conclusions

The exploratory analyses and information presented at the workshop suggested that the higher BFAL interaction rates in the Hawaii deep-set longline (DSLL) fishery in 2015-2016 may be largely explained by environmental conditions associated with the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).

During quarter 1 of years with positive PDO and ENSO conditions (2015, 2016), winds north of 25oN latitude switch from trades to westerlies. This change in wind direction results in more productive surface waters in the fishing grounds during quarters 1 and 2, and an apparent eastward shift in BFAL distributions into the fishing grounds. The Transition Zone Chlorophyll Front (TZCF), an important foraging habitat for BFAL, also shifts south, bringing it into the northern edge of the fishing grounds. In summary, these oceanographic shifts increase the spatial overlap of BFAL distributions with the Hawaii DSLL fishery during years of positive PDO and ENSO conditions.

The spatial distributions of fishing effort and mitigation measures during quarters 1 and 2 of 2015 and 2016 were not anomalous in a longer-term context (2004-2016). While quarter 3 fishing effort has shifted further eastwards over the past decade, these months (July-September) are not a time of substantial albatross-fishery interactions. Because BFAL interaction rates and abundance around vessels are positively correlated, workshop participants identified factors that may influence BFAL vessel attendance, such as breeding population dynamics (e.g., reproductive success), mesoscale features (e.g., eddies), and increased albatross attraction to vessels (e.g., fishing practices, albatross learning).

Population models, updated for the workshop, indicated that the DSLL interactions in 2015–2016, if stabilized at this higher level, are likely to have an imperceptible impact on BFAL population growth. However, if these elevated bycatch rates are consistent throughout North Pacific longline fisheries with BFAL interactions, the population is projected to decline. While North Pacific-wide bycatch estimates are not available, data from Alaska fisheries suggest that the 2015–2016 increase is unlikely to be basin-wide.

As next steps, workshop participants discussed moving towards an Integrated Population Model (IPM), building upon the current BFAL demographic model by integrating the multiple available data sets and perspectives. Yet several data gaps must be addressed to develop an IPM, involving an improved understanding of at-sea distribution, bycatch rates, and survivorship of birds from different colonies. In particular, tracking studies at the main breeding sites are needed to determine the degree to which birds overlap and interact with fisheries. While tracking has occurred at three breeding sites (French Frigate Shoals, Midway Island, Kure Atoll), birds from several sites in the Northwestern (Laysan Island) and the main Hawaiian Islands (Necker, Nihoa, Kaula) have not been tracked. 

Workshop participants also stressed the need for continued population monitoring at Midway Island to update the uninterrupted time series of breeding and reproductive success data.  They also indicated the importance of resuming breeding population counts at French Frigate Shoals and Laysan Island, two colonies that were historically surveyed by the U.S. Fish and Wildlife Service (USFWS) but are no longer monitored.

Acknowledgements

This workshop would not have been possible without the funding of the Council and NOAA National Marine Fisheries Service Pacific Islands Regional Office (PIRO), through Award No.NA15NMF4410066 and No.NA15NMF4410008.

Twenty-eight local, national, and international experts attended this two-day workshop, with several participants flying in from France, Japan, and Australia. We thank them for sharing their knowledge and their time so generously. Finally, we thank Council staff who facilitated the meeting and travel logistics for the participants, and Catherine Pham, who helped with the formatting and editing of the report. Johanna Wren and Katie Davis critically reviewed the workshop report.