Abandoned, lost or otherwise discarded fishing gear is a significant source of marine litter with about 640,000 metric tons lost or dumped in the ocean each year.
This "ghost" fishing gear is one of the most harmful forms of marine debris in the oceans today as it traps and kills marine wildlife randomly and unselectively. There are also concerns about chemical contamination with disruptive effects on marine species. As a result, human health is also impacted, with marine litter serving as a vehicle for diseases that contaminate the food chain.
A team of researchers led by Falk Schneider from National Cheng Kung University (NCKU), Taiwan, has conducted a material flow analysis of several types of fishing gear with a goal of supporting policy on marine litter prevention policies related to nets and other equipment.
Taiwan, with a flourishing fishery industry and one of the world's largest fishing fleets, is one of the countries contributing significantly to the problem with an average of 12.7 cubic meters of marine litter accumulating per kilometer along the coastline, 70 percent of it from fishing gear.
However, the country has lacked precise data aimed at preventing marine litter.
The project at NCKU addressed the following three questions: How much fishing gear stock is actually in the system? How to stop fishing gear from turning into ocean waste? And, what policies are needed to effectively manage fishing gear?
The researchers first created a stakeholder map to establish the general flow structure of the commercial fishing gear used in Taiwan. The life cycle of the fishing gear was divided into five stages: use, repair, storage, spillage to the ocean and end-of-life.
Following that, stakeholders from both government agencies and private companies were approached to gather quantitative data on current fishing gear stocks and flows. Next, the material flow analysis software STAN 2.7 was used to analyze the data and visualize the material flow model to identify pollution hotspots and spillage points.
The total input was estimated to be 8,846 metric tons per year, with the total output being 4,271 tonnes per year. About 2,722 tonnes of fishing equipment were estimated to be lost or dumped in the ocean annually after being used. Some 1,172 tonnes of fishing gear required maintenance, 1,062 tonnes were stored in the harbor, and 3,529 tonnes entered the end-of-life stage. A total of 1,538 tonnes of waste fishing gear were recycled; 2,630 tonnes were incinerated while another 103 tonnes went to landfill.
The project painted a dispiriting picture of the way waste fishing gear is dealt with: literally tons of commercial fishing gear are dumped into the ocean every year, while over another ton of discarded gear is left untreated in harbors for storage.
The project yielded insights into a few critical steps that could be taken to transition to a more sustainable fishing industry, Schneider said.
"The Taiwanese government must collect data in a systematic manner to monitor and manage the fishing gear waste streams," he said. "Furthermore, a meeting should be convened between stakeholders from the fishery sector, government agencies, and non-governmental organizations to facilitate knowledge sharing toward more sustainable fisheries."
The research could serve as a foundation for the dissemination of best practices for preventing marine litter in Asia and around the world, he added.