Under the warm rays of a winter sun, we arrive at the Jijin Cooperative, the largest private-sector oyster washing operation in Chiayi County’s Dongshi Township, where many oyster farmers from the surrounding region bring their harvested oysters to be washed and shucked. The cooperative also handles waste oyster shells and shellstring cords.

On the day of our visit, a large truck has brought oysters from Tainan. Oyster shellstrings loaded in large plastic baskets are tipped into separation machines, and in an instant the oysters are stripped from the cords that hold the shellstrings together.

The shellstring cords are transported to a holding area to be dried in the sun, after which workers drive a compact loader over them to crush any oyster shells that remain attached to the cords. Then the shell-free cords are washed and dried in the sun again. Finally, they are baled and shipped to the Formosa Chemicals and Fibre Corporation (FCFC) in Chiayi’s Xingang Township, where they enter the next stage of the recycling process.

The hard part about recycling fishing nets is that it takes a great deal of human labor to disassemble, sort, and recycle the various materials used in them.

Zhang Huichuan, director of the Chiayi County Environmental Protection Bureau, says that the most difficult step in recycling marine debris is finding uses for the recovered materials.

Finding uses for waste shellstring cords

Oysters feed on plankton, and farmers thread synthetic cords through oyster shells to create shellstrings (a.k.a. clutch strings), which they suspend in seawater. Oyster spat (larvae) attach themselves to the shellstrings to grow into oysters that can be harvested in as little as six months or as long as two or three years.

Oyster aquaculture in Taiwan is mainly concentrated along the southwest coast in Changhua, Yunlin, Chiayi, and Tainan, as well as in Penghu and Matsu. Two townships in Chiayi County—Dongshi and Budai—produce 9,181 metric tons of oysters annually, accounting for 47.15% of the national total. Based on the area occupied by oyster farms in Chiayi, the county government calculates that within its jurisdiction some 1,300 metric tons of waste oyster shellstring cords are generated each year.

This is enough cord to circle Taiwan’s coastline ten times over, and that doesn’t include the quantity ­attached to oysters sent to Chiayi from other areas to be washed.

When synthetic shellstring cords are immersed in seawater, they harden over time, so they can only be used once. Formerly there was no place to dispose of the discarded cords, creating a major problem for the local government.

“When colleagues went to the mouth of the Bazhang River in 2019 to do a survey of undersea debris, they discovered that there were many lengths of hard material like steel wiring. After bringing some back for analysis, it turned out that these were oyster shellstring cords that had been immersed in the sea for a long time,” says Zhang Huichuan, director of the Chiayi County Environmental Protection Bureau (CCEPB).

Four years ago, former CCEPB director Chang Ken-mu visited FCFC to explore whether there was any way to reuse shellstring cords. At that time, no one at FCFC knew what kind of plastic is used to make these cords. Analysis showed that they are composed of Nylon 6 (N6), so a recycling plan was proposed.

The plastic cords used in oyster shellstrings harden over time when immersed in seawater, making them single-use products.(photo by Mei Kuo)

When aquaculturists bring harvested oysters to a washing facility for processing, it provides an opportunity to recover the shellstring cords. (photo by Kent Chuang)

Waste oyster shells that enter the circular economy can be used to make building materials, footwear, fabrics, and more.(photo by Kent Chuang)

“We produce, we recycle.”

“We were already recycling N6 and turning it back into caprolactam, its main ingredient, but the material we were recycling was production waste.” FCFC’s fiber and yarn production includes N6 products, and it recycles N6 production waste using depolymerization technology. Recycling N6 shellstring cord would not be difficult, but only three companies in the world have the technology to do it: FCFC, Korea’s Hyosung Corporation, and Italy’s Aquafil.

FCFC’s involvement in N6 recycling goes back 2018, when it began working with the international clothing brand Patagonia. At that time FCFC’s Vietnam plant started converting waste nylon fishing nets back into caprolactam (CPL) and using this to make environmentally friendly yarn, which was supplied to Patagonia to produce functional outdoor and sporting attire. CPL also has industrial uses and can be used in knitted fabrics.

In 2022 FCFC signed a letter of intent to work with the world’s second-largest manufacturer of fishing nets, Kaohsiung-­based King Chou Marine Technology, to recycle fishing nets. At that time FCFC chairman Hong Fu Yuan said that the company’s goal was to put into practice the corporate social responsibility principle of “We produce, we recycle.”

At the FCFC factory in Xingang, staff take us on a tour of the production line to learn about the recycling process for oyster shellstring cords and fishing nets. Workers use test instruments to verify that all the material is N6.

Shellstring cords that have been cut into short lengths are put into melting tanks are certified as meeting the Global Recycled Standard requirements. After melting, the material is depolymerized, refined and filtered, turning it back into the main ingredient of N6 fiber, CPL.

This material is then taken to the filament plant to be remanufactured. The CPL is heated in tanks with an added catalyst, resulting in polymerization into N6, which is formed into pellets. These are extruded into N6 filament, which is spooled, packaged, and shipped to downstream plants for processing.

“There is no significant difference between remanufactured CPL and virgin CPL refined from petrochemicals.” Remanufactured CPL requires 15% less electricity to produce than virgin CPL, reduces carbon emissions by 49%, and decreases the use of petroleum, thereby saving global resources.

In the future, the FCFC factories in Taiwan and Vietnam are expected to have a combined capacity to recycle 1,250 metric tons of nylon fishing nets and oyster shellstring cords. In recent years, FCFC has been turning waste nets and shellstring cords into environmentally friendly yarn that it supplies to major brands including Nike, Adidas, Patagonia, and Formosa Taffeta Company, who use it to make technical apparel.

Freshly harvested oysters are tipped into a roller machine that separates the cords from the shellstrings, enabling the cord material to be recycled.

The cords used in oyster shellstrings harden after being immersed in seawater for a long time, so they can only be used once.

Workers drive a compact loader over piles of waste shellstring cords and fishing nets drying in the sun. (photo by Kent Chuang)

After shell debris is removed from waste shellstring cords and they are dried in the sun, they can be sent to Formosa Chemicals and Fibre Corporation (FCFC) for recycling as part of the circular economy.

Building a recycling value chain

“There are three main problems with recycling marine waste,” says Zhang Huichuan. For example, he notes, the biggest challenges to promoting the recycling of waste fishing nets and oyster shellstring cords are how to get fishermen to participate, where to temporarily store recyclable material, and finally, and most importantly, what it can be used for.

Zhang says that after marine waste is recovered, ultimately there must be channels to dispose of it. If high-­value-­added products can be made from it, this will increase the incentives to recover the material. For example, the Swedish brand Fjällräven uses plastic made from recycled shellstring cord from Taiwan as one of the materials for its backpacks. This kind of high-quality reuse increases the value of recycled shellstring cords by 100–200 times. When Chang went to Sweden, he brought back some of these backpacks as gifts, and when he told people to whom he gave one, “This is made using waste oyster shellstring cords,” they were astonished.

In 2020 the Ocean Conservation Administration (OCA) instituted a program of coastal cleanups under a policy called “Salute to the Sea: Coastal Cleaning and Maintenance Program.” Under the program the OCA aims to integrate the industrial chain for marine waste recycling, including subsidizing 19 coastal cities and counties to clean up marine debris; outsourcing tasks related to cleaning up Taiwan’s seas and recycling marine waste; establishing the Ocean Cleanup Alliance and calling on citizens to take part in beach cleanups; and recruiting fishermen to join the Environmental Protection Fleet and citizens to monitor inshore waters, to assist in cleaning up both sunken and floating marine debris.

For example, the Chiayi County Government has set up special areas for recycling fishing nets and oyster shellstring cords in the fishing ports at Dongshi and Budai. It pays a high price of NT$15 per kilo for these materials and provides fishermen with other incentives to recycle, thereby increasing their willingness to participate. The county also contracts specialized businesses to separate out recyclable materials and clean off impurities, after which they are supplied to FCFC.

In 2021 the OCA brought together recycling businesses, brand owners, design firms, and financial and research institutions to form the Marine Debris Recycling Coalition. The coalition develops products that reuse marine waste and already has 49 participating enterprises.

Companies are using recycled material from discarded fishing nets to make many products, including eyeglass frames, infant-friendly towels that are soft to the touch and meet CNS 15290 safety standards for textiles, shampoo bottles, and office chair casters.

In addition, Taijei Precision Company is recycling thermo­plastics (polymer materials that soften when heated and solidify when cooled), mainly recycling fishing gear floats, buoys, expanded polystyrene, and high impact polystyrene. They combine recycled material with other inputs to make composite materials which they use to produce industrial pallets, display racks, classroom desks and chairs, cabinets, gazebos, small cabins, storage baskets, stools, cell phone cases, and more.

Taijei chairman Luka Liou says: “By recycling thermoplastics we can make materials that have the texture of wood or lumber building materials, which many visitors to our company find amazing.” Taijei has also been invited by the Indonesian government to join in a project to transform one of the country’s major cities into Southeast Asia’s first net-zero green demonstration city. Taijei will guide the city in handling the disposal of thermoplastics, planning the equipment for a production site, and training technical personnel.

OCA director-general Julia Hsiang-wen Huang says that now that waste fishing nets have economic value, fishermen and enterprises are more willing to take the initiative to recycle them. Taiwanese businesses have the technology to handle this material, and there are prospects for future transnational cooperation, providing solutions to issues of sustainability and environmental protection.

An employee at FCFC explains the process of turning discarded fishing nets and shellstring cords back into caprolactam.

FCFC personnel use test instruments to check that waste fishing nets are made of Nylon 6.

FCFC uses chemical depolymerization technology to turn waste fishing nets and shellstring cords back into caprolactam.

Reclaimed caprolactam can be manufactured into environmentally friendly yarn.

The rise of the circular economy

Xiao Mingfu, chairman of the Chiayi County Oyster Aquaculture Association, not only farms oysters but also fishes, and his front yard is like a miniature fishing gear factory. He makes oyster shellstrings and fishing nets himself, and also takes apart waste fishing nets. The floats and weights that he uses for new nets are made from recycled materials.

“In the old days discarded fishing nets weren’t worth anything, but now that there are subsidies for recycling fishing gear, people will even pick up any fishing nets tossed away by the roadside.”

The island of Xiaoliuqiu off the coast of Pingtung County is Taiwan’s one and only coral reef island, and is a popular tourist destination.

Over the past 14 years, Xiaoliuqiu’s Ocean Volunteers have made 430 dives and cleaned up a lot of marine debris including many discarded fishing nets. In addition, the government has banned gillnet fishing in these waters. The coral reefs now have a chance to survive, providing a habitat for undersea life, says Hsu Po-han, head of the volunteers.

“Discarded fishing nets are very damaging to the ecological chain of life. It may seem hard to imagine, but many of our volunteers used to arm themselves with spear guns and set up undersea fishing nets, but now they see things differently,” says Hsu.

Waste oyster shellstring cords, discarded fishing nets…. Let’s take a moment to reflect on the fact that the ocean is not merely the basis for seafood culture or the source of materials for the circular economy. We should also consider how to prevent further degradation of the marine environment.

FCFC personnel use an added visual inspection to ensure the quality of the yarn.

Recovering caprolactam from waste fishing nets and oyster shellstring cords saves electricity and reduces carbon emissions as compared to refining virgin caprolactam from petrochemicals.

The ocean is not just the source of seafood culture. We should also think about the meaning of marine culture. (photo by Kent Chuang)