Research Highlight: New Tool to Forecast Fishing Activity in Palau's Waters

Researchers at Scripps Institution of Oceanography at the University of California San Diego have created a system to forecast fishing activity in the exclusive economic zone of a Pacific island country whose territorial waters cover an area greater than the size of France.  

Palau, a country with 177 square miles of land, is preparing to close most of its 232,000 square miles of territorial waters to commercial fishing as part of its National Marine Sanctuary program. Researchers say this new tool could prove to be crucial for future monitoring and enforcement of that area.

Their study was published January 24 in Nature Scientific Reports.

Scripps researchers Eric Terrill, Megan Cimino, Mark Anderson, Sophia Merrifield, and Travis Schramek partnered with the Republic of Palau and the U.S. Office of Naval Research on this study to understand how fishing locations change in response to environmental conditions over multiple years. Most countries like Palau require licensed fishing vessels to be equipped with vessel monitoring systems (VMS) that continuously track ship movement. Using VMS data from 2011-2016, the researchers analyzed more than one million vessel locations to develop fishing tracks that were used to identify fishing patterns and hotspots. The vessel activity was assessed against past ocean conditions to estimate where fishing activity is most likely to occur at any given time.

This study is one of the first of its kind to document the near-immediate response of fishing activity to fine-scale physical ocean conditions over many years, and even changes associated with an El Niño event. As the scientific community is becoming more adept at forecasting change in the ocean, the study suggests location-based fishing pressures can also be forecast with detail not previously possible.  

Models like these have been traditionally done on smaller scales on an annual basis, not recognizing that in the case of fisheries, enforcement happens throughout a country’s exclusive economic zone (EEZ), which typically extends out to 200 nautical miles from a country’s shore. For nations made up of multiple islands, the distance makes both monitoring this zone technically challenging and costly to implement with patrol boats.  

“Unique to this study was merging millions of fishing vessel locations with high resolution ocean information that emerged from our oceanographic studies sponsored by the U.S. Office of Naval Research,” said Eric Terrill, Scripps researcher and head of the research team that led the study. “Scripps has had a wonderful science partnership with Palau since 2010, and the study was an attempt to transition our science to support conservation and management challenges they are facing.”

By 2020, Palau plans to close 80 percent of its EEZ to commercial fishing, with nearshore areas open for domestic use and most offshore pelagic fishing grounds no longer accessible to foreign fleets. The study is part of a large-scale strategy set in motion in 2015 with Palau’s Monitoring, Control and Surveillance (MCS) Plan to implement protections and subsequent monitoring and enforcement strategies that will be used by government officials. Scripps is playing an active role in facilitating the integration of cutting-edge science and technology to these emerging environmental issues, and assisting the Palauan government in the development of this plan.

“One of the main goals for this study is to help make monitoring and enforcement efforts more efficient,” said Megan Cimino, lead author of the study, who completed this research as a postdoctoral researcher at Scripps. “Palau’s land area is only 177 square miles, and they have to police an ocean area the size of France.”

Beyond monitoring fishers, the findings can help Palau’s resource managers better understand migratory and pelagic species like tuna that are some of the most commercially important fisheries in the tropical Pacific. Offshore species are also the target of many illegal fishing operations; by better understanding the habitat of fish stocks based on legal fishing, researchers can help predict where illegal fishing may occur and the enforcement agencies can target these areas with various surveillance technologies.

This method could be used to develop the most optimal location for fishing closures or to create real-time forecasting systems to support surveillance aircraft or patrol boats. The study also holds value for other nations in the Pacific that have large EEZs relative to their country size and few enforcement resources. For Palau, the next steps will involve creating live forecasting systems that predict where fishing activity will likely take place based on real-time ocean conditions.

This research was funded by the U.S. Office of Naval Research under the Flow Encountering Abrupt Topography (FLEAT) research initiative.