Climate driven spatiotemporal variations in seabird bycatch hotspots and implications for seabird bycatch mitigation

Area of Science:

• Marine biology
• Fisheries science
• Conservation ecology

Background:

• Fisheries bycatch poses a significant threat to seabird populations globally.
• Understanding spatiotemporal dynamics of bycatch is crucial for effective mitigation strategies.
• Long-term data from the U.S. Atlantic pelagic longline fishery offer insights into these patterns.

Purpose of the Study:

• To analyze inter-annual spatiotemporal patterns of seabird bycatch in the U.S. Atlantic pelagic longline fishery.
• To develop and apply a Bayesian model for predicting seabird bycatch hotspots.
• To explore the correlation between environmental factors, like Gulf Stream meanders, and bycatch patterns.

Main Methods:

• Utilized data from the National Marine Fisheries Service Pelagic Observer Program (POP) since 1992.
• Developed a fast-computing Bayesian approximation method to model spatiotemporal bycatch data.
• Applied the model to logbook data, accounting for coastal barriers to estimate bycatch per set.

Main Results:

• Identified the Mid-Atlantic Bight and Northeast coast as areas with the highest estimated seabird bycatch.
• Found a correlation between inter-annual changes in bycatch hotspots and Gulf Stream meanders, with a notable lag.
• Demonstrated that a higher Gulf Stream North Wall index predicted more northerly bycatch hotspots two years later.

Conclusions:

• Gulf Stream meanders provide a predictable signal for future seabird bycatch hotspots.
• Shifting fishing operations to adjacent areas or times can significantly reduce seabird bycatch.
• Conservation strategies can be enhanced by integrating oceanographic predictions into fishery management.