More than 100 million pounds of plastic from industrial fishing gear pollute the oceans each year—threatening marine life.

Scientists with The Nature Conservancy and the University of California, Santa Barbara (UCSB), along with the Pelagic Research Group and Hawaii Pacific University, released a new peer-reviewed study that provides the first global estimate of plastic pollution from industrial fisheries. The study reveals that more than 100 million pounds of plastic pollution enters the ocean each year from lost fishing gear—providing the baseline information needed to improve understanding of the problem and drive reforms to mitigate the flow of fisheries’ plastic pollution.

In the study, Plastic gear loss estimates from remote observation of industrial fishing activity, published in Fish and Fisheries, scientists analyzed big data from Global Fishing Watch and the Food and Agriculture Organization of the United Nations (FAO) to estimate the scale of industrial fishing activity and combined this information with technical models of fishing gear and expert knowledge to predict upper and lower bounds of plastic that was lost in the ocean during 2018. The study focused on the three largest industrial fisheries, representing 74% of industrial fisheries harvest.

“Until now, we have had little understanding of the magnitude of the problem,” said lead author Brandon Kuczenski, environmental science researcher at the University of California, Santa Barbara. “Plenty of work has been done at regional scales but this is the first attempt to develop a global estimate of fisheries-derived plastic pollution based on observed fishing effort. By combining satellite data with expert understanding of industrial fishing operations, this research is the first step in developing a global database that includes all fishing vessels.”

An estimated 4.6 million fishing vessels ply ocean waters, setting fishing gear across every ocean basin. The research team focused initial analysis on industrial fisheries which operate large vessels and stay at sea for weeks and months at a time. Satellite tracking devices on these vessels allow scientists to determine the type of fishing that is occurring wherever those boats may be. Such tracking is not yet possible for smaller sized vessels that typically fish closer to shore.

The study, which accounted for over half of all marine capture, only addressed fishing gear that was lost during use.

“We know that intentional discarding and abandonment could match or even exceed unintentional loss. This means that our estimates are on the low end of how much plastic is actually entering the water from fishing activities,” said Kuczenski.

Unlike other forms of marine debris, fishing gear is specifically designed to catch marine life. Under certain conditions, derelict gear can continue to catch and kill organisms for years. This ghost fishing affects vulnerable species such as sharks, rays, seabirds, marine mammals, and marine turtles, as well as principal market species that are targeted by the fisheries.

“The impacts from lost fishing gear such as nets, traps, fish aggregating devices (FADs), and lines can continue to pose serious risks to the environment long after they become derelict,” said coauthor Eric Gilman, marine research scientist at Hawaii Pacific University. “In addition to ghost fishing, derelict gear can transfer toxins and invasive species, distribute microalgae that may cause harmful algal blooms, alter and damage coastal and marine habitats, disrupt navigation and other fishing activities, reduce the socioeconomic value of coastal and nearshore areas, and break into microplastics which pass through the food chain.”

Although all types of lost fishing gear can pose threats to ocean ecosystems, plastic components, which now make up a significant fraction of many gear types, create considerable concerns.

“Lightweight plastics are now present in almost all types of fishing gear because of their durability and low cost,” said Gilman. “Using weight as the means to measure the impact doesn’t substantiate the scale of the problem. In fact, if all that lost gear were fishing line, it would stretch to the moon and back more than 5 times.”

Fishing gear becomes lost for many reasons including bad weather, gear malfunctions, vandalism, snagging on bottom habitat, and other causes. So, developing solutions to this problem requires understanding the context and developing tailored solutions.

“We know there are ways to mitigate lost fishing gear,” said coauthor Jono Wilson, ocean scientist at The Nature Conservancy in California. “To protect our oceans, we need to take targeted action that starts with working together and understanding this complex problem at a local and global scale. This study is an essential first step in getting to solutions. Moving forward, we’ll be using these findings and working with a broad range of partners to find lasting, scalable ways to reduce this significant part of the plastic pollution picture. And we’ll be looking to start in those fisheries and regions that today are contributing the most.” 

Chris Voss, President of the Commercial Fishermen of Santa Barbara has been leading fishing gear cleanup efforts off the coast of California, “Losing gear is the last thing a fisherman wants to do. We believe smart and sometimes simple strategies can be developed to reduce gear loss. By working together, constructive steps can be taken to minimize this loss and the resulting impact; fisherman want and need to be a part of this equation.”

How fast and how far these solutions can be implemented will determine whether people can stem the tide of plastic pollution and environmental degradation of the ocean.