Industrial fishing poses greater risk to marine life due to untracked activity, UC Santa Cruz researchers say
A new study led by a scientist from UC Santa Cruz Marine Science Institute reveals that blue whales, tuna and other large predators in the northeast Pacific Ocean face a higher risk of harm from industrial fishing than previously thought.
The team behind the study, published March 6 in Scientists progressstarted with previously collected data on when fishing vessels intentionally disabled their location system or have lost their signal due to technical problems. The study authors then overlaid the habitats of 14 large marine species – including endangered or critically endangered species like blue whales and leatherback turtles – and found that the risk to these creatures increased overall by almost 25% when representing the presence of these so-called marine species. “dark ships”.
“We know that many marine creatures, including endangered species, are killed by overfishing, bycatch and entanglements in fishing gear,” said Heather Welch, project scientist at the UC Santa Cruz Marine Science Institute. “Similar risk estimates are used in species stock assessments to decide their populations and catch limits. For example, how many tuna can we pull out of the water? Well, if the risks are more higher than we think, catch limits may need to be lowered.”
Why are fishing boats dying?
Researchers examined five years of data from fishing boat tracking devices collected by Global Fisheries Monitoringwhich campaigns for total transparency of fishing activity around the world through the adoption of national and regional regulations mandating the use of automatic identification systems (AIS) on all industrial fishing vessels. Patchwork AIS requirements set by different countries mean that turning off AIS may be legal on the high seas.
In this study, the majority of untracked fishing activities were due to AIS being turned off due to technical issues such as poor satellite coverage or signal interference. And in the same way that anyone can turn off location tracking on their mobile phone, fishing vessels can intentionally take AIS offline whenever they want to hide their presence.
Sometimes it is necessary to turn off location tracking, for example when a ship is in waters where pirates are known to be. It’s not necessarily illegal either. For example, U.S. fishing vessels only need to activate AIS when they are within 12 nautical miles of shore, Welch explained. Nonetheless, the study authors insist that fishing vessels should have AIS enabled wherever possible, both for transparency and safety reasons.
“We have huge blind spots compared to what humans are doing at sea,” Welch said. “Imagine, for example, if we didn’t know at any given time where 19% of our planes were. It would be chaos.
Shedding light with data
In their previous study using the AIS dataset, the researchers identified more than 55,000 intentional potentially disabling events between 2017 and 2019, masking nearly 5 million hours of fishing vessel activity. More than 40% of the total hours masked by suspected AIS deactivation occurred in four hotspots, three of which are areas of concern for illegal fishing: the Pacific Northwest and areas adjacent to the areas exclusive economic interests of Argentina and West African countries. These areas contain rich fishing grounds with limited management oversight.
However, the latest hotspot – located in the Bering Sea – is one of the most intensively managed and monitored fishing grounds in the world. Intentional deactivation in these waters is done to avoid alerting competitors to the location of high quality fishing grounds.
At a time of growing concern about overfishing and the resulting massive amounts of bycatch, the authors say the underestimated risk to sensitive species is even more alarming.
In an article she wrote for The conversation, Welch discusses the overlap between where industrial fishing occurs and the habitats of top predators: observable fishing activity has been found in over 45% of California sea lion habitat and in nearly a third of salmon shark habitat. When dark vessels were taken into account, the risk estimates for these species increased by 28% and 23%, respectively.
Implications for policy and openness
In light of these findings, regulators and agencies may want to revisit the commercial fishing limits and endangered species designations they oversee. The study also highlights the need for better and more accessible data on human-wildlife interactions at sea. Besides AIS, other major data sources in the United States are the National Vessel Monitoring System, observer data and logbooks. But this information is confidential and rarely shared between flag states.
Other co-authors of the UC Santa Cruz study include assistant research scientist Megan Cimino and research associate Elliott Hazen, both assistant professors at UC Santa Cruz. Global Fishing Watch contributors included Tyler Clavelle, Timothy White and David Kroodsma.
The study was funded by the National Oceanic and Atmospheric Administration’s Office of Law Enforcement and inspired by NOAA’s strategic plans on combating illegal, unreported, and unregulated fishing activities.
