Most commercial nets (trawl nets, gillnets, seine nets, etc.) are woven from synthetic polymer fibers. Common materials are polyamide (nylon) – especially Nylon-6 or Nylon-6,6 – and polyethylene (PE) (often high-density PE)[3][4]. These plastics are strong, flexible, and resistant to rot, which is why polyamide, polyethylene, and polypropylene fibers gradually replaced natural fibers like cotton or hemp in fishing nets since the mid-20th century[1]. Nylon monofilament (a single-strand nylon line) is widely used for invisible fishing lines and gillnets, while PE (e.g. HDPE) is used in some netting for its buoyancy and toughness[3]. Nets can also be made of polyester (PET) in some cases, or advanced polymers like UHMWPE for high-strength applications[5][3]. These materials are all non-biodegradable, so if lost they can drift in the ocean for years[3].

Fishing ropes (for longlines, trap lines, tow ropes, etc.) are typically made from polypropylene (PP) or polyethylene (PE) fibers, or blends of both[6]. Polypropylene rope is very popular because it is lightweight, floats on water, and does not absorb water, making it ideal for surface lines or buoy lines[7][8]. Polypropylene is also chemically resistant to salt and oils and is relatively inexpensive[9][10]. Polyethylene rope (often high-density PE) similarly resists rot and is used in many marine applications. Nylon (PA) rope is used where higher strength and elasticity are needed – for example in heavy-duty mooring lines or trawl warps – because nylon ropes have very high tensile strength and can absorb shock loads due to their elasticity[11][8]. However, nylon is heavier (it sinks in water) and more expensive, so fishermen balance uses of PP vs PA ropes depending on needs[8][12]. In Vietnam and worldwide, ropes for lobster/crab traps and nets are commonly PP or PE (or a PP/PE blend) for cost-effectiveness[6].

These include the round or cylindrical floats attached to nets or marking lines, as well as larger buoys marking gear positions. Hard plastic floats are typically made of high-density polyethylene (HDPE) or other tough co-polymer plastics[13][6]. HDPE buoys are durable, UV-resistant, and often hollow air-filled or foam-filled for buoyancy. Some designs use a hard polyethylene shell filled with foam (like EPS or EVA) to prevent total loss of buoyancy even if cracked[14]. In the past, expanded polystyrene (EPS) foam (Styrofoam) was sometimes used directly as net floats or buoyant blocks because it’s very lightweight. However, EPS breaks apart easily and is prone to polluting the ocean with foam fragments, so most modern fishing floats use tougher plastics (e.g. hollow polypropylene or PVC floats, or EVA foam floats) rather than exposed EPS[15]. Larger marker buoys for traps or moorings may still incorporate rigid plastic floats and sometimes polyurethane foam internally for strength. Overall, buoys in lobster and crab fisheries today are often plastic (vinyl or polyethylene) on the outside, sometimes with foam cores, to withstand harsh marine conditions[6].

Lobster, crab, and fish traps are rigid structures that traditionally were made of wood, but now commonly use metal and plastic components. For example, lobster pots in many countries are made of galvanized steel wire mesh coated in PVC (polyvinyl chloride), a thermoplastic coating that prevents rust[16]. The coating and any mesh netting on traps are plastic, even though the frame is metal. Some traps are made entirely of plastic rods or heavy-duty plastic (e.g. rigid HDPE slats) to avoid corrosion. These synthetic traps last much longer than wood – modern PVC-coated wire traps can last years in the ocean[17]. The ropes connecting traps are polypropylene/PE as noted, and the marker buoys for traps are plastic or foam. In Vietnam’s crab and lobster fisheries, as elsewhere, these synthetic materials are common for durability. (Note: PVC is a thermoplastic polymer used here for coatings, though it differs from the pure thermoplastics used in fibers because of additives.)

A notable plastic in fisheries is the foam “Styrofoam” box used to store and transport catch. Expanded Polystyrene (EPS) boxes are ubiquitous in seafood supply chains for ice storage of fish and shrimp because EPS is lightweight, provides excellent thermal insulation to keep fish cold, is waterproof, and cheap[18]. A typical fish cold-storage box is a white EPS foam crate – it insulates so well that it’s ideal from boat to market. However, these boxes are often single-use and easily broken. EPS boxes have good impact protection and stacking strength when new[18], but once cracked they can shed small foam pieces. Other storage and handling gear includes plastic fish crates (often rigid HDPE or PP crates) and buckets, which are washable and reusable. In Vietnamese fisheries, Styrofoam ice boxes are commonly seen at ports and markets for their cooling ability, but their disposal is a growing environmental concern.

This polymer (especially High-Density PE) is widely used for nets, ropes, and floats. PE is lightweight (density ~0.95 g/cm³) – it naturally floats in water[21]. It is slightly less strong than some other plastics, but highly flexible and wear-resistant, which gives nets and ropes made of PE a long service life[22]. PE fibers or twines resist abrasion and chemicals; they don’t rot or absorb water. HDPE in particular is a tougher, stiffer grade of polyethylene with higher tensile strength and UV resistance, used for things like ropes, cages, and hard plastic buoys. For example, HDPE is used to mold durable buoys and floating pontoons that are UV-stabilized and impact-resistant[13]. Both LDPE (low-density PE) and HDPE are thermoplastic and recyclable. A downside of PE is that it’s somewhat slippery and has lower melting point (~130°C) than nylon, but this usually isn’t an issue in water. Overall, PE’s buoyancy and toughness make it perfect for gillnets, purse seines, and many rope lines. (Note: Ultra-high-molecular-weight PE, UHMWPE, known by brands like Dyneema, offers extremely high strength for its weight and is used in some specialty fishing lines and nets where extra strength is needed[23].)

Another polyolefin plastic, PP is actually a bit lighter than water (density ~0.90 g/cm³), so it floats even better than PE. Polypropylene fibers and ropes are highly water-resistant (zero water absorption) and chemically resistant to fuels, oils, and solvents – an important property for marine use[7][9]. PP does not degrade in saltwater and it doesn’t mold or rot[10]. It is slightly less strong and less UV-resistant than polyamide, but it’s cost-effective and easier to handle due to its light weight[24][7]. In fishing, polypropylene ropes are common for tying nets, surface lines, and any application where floating line is preferred (so it doesn’t sink and snag on the bottom)[7][8]. PP is also made into fibers for certain nets or twines, and into hard plastic floats (some small net floats are made of injection-molded PP or PVC). Key properties: Lightweight, floats, good flex and abrasion resistance (though not as abrasion-proof as nylon)[25]. One limitation is lower melting point (~160°C) and UV sensitivity – long sun exposure can make PP brittle unless stabilizers are added[24]. Despite that, many fishing communities (including in Vietnam) favor PP ropes for being inexpensive and adequate for most tasks. Properly stored, PP gear can last a long time[26].

Nylon is arguably the most important fiber material for fishing nets worldwide. Nylon 6 (polycaprolactam) and Nylon 6,6 are both common; here we focus on Nylon-6 (PA6). Nylon is known for its exceptional tensile strength and elasticity[27]. A nylon net can bear heavy loads (big catches) without breaking, and it will stretch under sudden force (e.g. a struggling fish) and recover its shape, rather than snapping[27]. This strength and stretchiness improves the durability and catch efficiency of nets – they are less likely to tear and can absorb shocks[27][28]. Nylon also has excellent abrasion resistance, crucial since nets often drag over rocks or boat decks[29]. Another advantage is low water absorption: PA6 does absorb some water (unlike PP/PE, it’s slightly hydrophilic), but Nylon-6 is engineered to absorb minimal moisture so it doesn’t significantly weaken or swell when wet[30]. It also can be formulated with UV inhibitors to resist sun damage[20]. All these make nylon nets long-lasting. For example, gillnets and trawl nets made of Nylon-6 can be used repeatedly with heavy loads, reducing how often gear must be replaced[31]. Nylon’s drawbacks include being heavier (density ~1.14, so it sinks in water) and more expensive than PP/PE[8][32]. It also loses some strength when wet (and takes time to dry) and can degrade if left in the sun without stabilizers[33][24]. In ropes, nylon’s weight means it’s not used where floating line is needed, but it’s favored for anchor lines and deep-sea applications because of its strength and shock absorption[11][32]. Overall, PA6’s high durability in nets helps reduce gear loss and replacement frequency, which is both economically and environmentally beneficial[34][35]. (Many programs recycle discarded nylon nets into new nylon products since the material retains value – see recycling section.)

HDPE is actually a type of PE but deserves mention because it’s specifically used in hard, rigid items and monofilament lines. Compared to regular (low-density) PE, HDPE has longer polymer chains with fewer branches, giving it higher density (~0.95-0.97) and crystallinity. This yields greater tensile strength, stiffness, and heat resistance. HDPE is used for monofilament fishing lines and net twines (e.g. some trammel nets or aquaculture cage nets use HDPE monofilament which is stiffer and holds its shape)[3]. It’s also the material for plastic fish crates, buoys, and floats because it can be molded into thick, tough shapes that withstand rough handling. HDPE floats (often orange or white hard plastic floats) are common on gillnets, longlines, and fish aggregating devices. The material is UV-resistant when stabilized and can last years in the sun. Like other PE, HDPE is chemically inert (won’t corrode or react) and non-absorptive. In summary, HDPE offers the same non-rotting durability of PE but in a stronger form – ideal for heavy-duty gear components like large buoys, pontoons, trap frames, and high-strength netting. (In Vietnam, for example, some modern fish farming cages use HDPE pipe frames floating on the water.) HDPE is recyclable and often collected (e.g. hard plastic floats can be reprocessed if recovered).

Polystyrene is a different kind of thermoplastic – a styrene-based polymer – usually seen in fishing in its foamed form (Expanded PS). Expanded Polystyrene is 95%+ air, making it extremely light and buoyant, which is why it became popular for fish coolers and some floats. EPS fish boxes have “unrivalled thermal insulation” to keep seafood fresh from boat to market[18]. They also provide shock protection and stacking strength for delicate cargo like fish on ice[18]. However, EPS foam is quite brittle – chunks break off easily – and it is infamous for polluting beaches and waters when not properly disposed[36]. Unlike the tougher polyolefins, EPS cracks and crumbles under stress, forming harmful microplastics. It is also bulky relative to its weight, making collection and recycling difficult (economically, since transporting “air” is costly). Some fishing floats in the past were simple blocks of Styrofoam tied to nets; these often disintegrated and contributed to marine litter. Today, there’s a move to replace EPS floats with durable plastic floats or to encase foam inside hard shells to prevent fragmentation[15]. In terms of pure material properties: polystyrene (unfoamed) is a hard, rigid plastic (think of rigid plastic cups), but expanded polystyrene foam is weak in tension and breaks under repeated load. It is not water-absorbent (closed-cell structure), but can grow waterlogged if heavily damaged. EPS is technically recyclable (it can be melted or compacted and remolded), but contaminated fish boxes often end up in landfills or are burned because cleaning and transporting them is a challenge. In summary, EPS (Styrofoam) provides great insulation and light weight, which is why it’s used for fish boxes and some buoyancy, but its environmental footprint is problematic when it becomes waste.

Discarded fishing nets and ropes have been successfully recycled in various projects. For example, used nylon nets can be cleaned and re-melted into nylon pellets or fibers to make new products like textiles and carpets[37][38]. One well-known case is the recycling of Nylon-6 nets into yarn for apparel (as done by some specialty fiber companies). Similarly, polypropylene and polyethylene gear can be mechanically recycled: ropes can be shredded and re-pelletized to produce items like plastic lumber, containers, or construction materials. In fact, waste fishing nets (typically PA or PE) have been chopped into fibers to reinforce concrete, adding strength to building materials[39]. There are also chemical recycling routes: heavily contaminated or mixed-plastic nets can be subjected to pyrolysis (heating without oxygen) to break them down into oil and fuels[40]. This oil can be used as a feedstock to make new plastics. Another method tested is gasification (high-temperature hydrolysis), which can turn shredded nets into a synthesis gas for energy or chemical production[41][42]. These advanced methods can handle dirty and mixed waste, though they are energy-intensive. Some components of gear can simply be reused directly: for instance, intact floats, weights, or even entire nets can sometimes be refurbished and given or sold to other fishermen or for other uses. In Norway, a gear retrieval program was able to return 50% of recovered fishing gear to fishers for reuse (after cleaning/repair) by 2024, showing that extending gear life is feasible[43]. There are also community initiatives (including in Vietnam) where old nets are repurposed for other industries – e.g. shredded nets used in making handbags, or ropes used in crafts – as a form of upcycling.

Despite these possibilities, recycling fishing plastics is far from straightforward. Some major challenges include:

Material Degradation: After years of use at sea, plastics often suffer from UV exposure, salt exposure, and physical wear, which can reduce their tensile strength and quality[44][45]. Recycled material from old nets may be weaker than virgin plastic, limiting its usability in new high-stress applications (e.g. you might not want to make a new fishing net out of recycled fibers if the strength is insufficient[45]). This means recycled gear plastics often have to be down-cycled into products that don’t demand high strength, or be reinforced/blended with other materials to be useful[46][45].

Mixed Materials & Design: Fishing gear is not made of a single uniform plastic – a net piece may include nylon mesh, polyester stitching, lead line weights, and plastic floats all in one unit. Many nets, ropes, and traps are multi-material composites, making separation difficult[46]. For example, trawl nets can have sections of different polymers, and lobster traps have metal and plastic together. Recycling processes generally require some level of sorting (e.g. you can’t easily recycle a mixture of nylon and polyethylene together, as they melt at different temperatures and produce a poor blend). Separating metals (like steel weights or hooks) from nets and removing other contaminants is labor-intensive. Gear design has not historically considered end-of-life recycling, though now there are discussions to standardize materials (e.g. use one type of plastic where possible) to improve recyclability[47].

Contamination (Biofouling & Debris): Old fishing gear is usually dirty – covered in seaweed, barnacles, fish residues, sand, etc. This organic and inorganic contamination poses a big challenge for recycling. Cleaning the nets is necessary before mechanical recycling, and that can be costly and water-intensive. However, some modern recycling efforts have developed methods to handle contaminants. For instance, specialized shredders and washing systems can remove sediments and separate organic matter[48]. Still, heavily biofouled nets might be unsuitable for recycling and end up in disposal. Additionally, hazardous substances can be present (e.g. lead from weights, or plastic additives), requiring careful handling. Some chemical recycling methods (like high-temperature gasification) can process nets without pre-cleaning, but those facilities are not widely available[41].

Economic and Logistical Barriers: Collecting and processing old fishing gear can be expensive. Fishing communities are often spread along remote coasts – in Vietnam, for example, thousands of small fishing boats land in villages that may lack waste management infrastructure. Transporting bulky nets and traps to recycling centers is costly (used nets are heavy and have low scrap value per kg). A Norwegian study found high costs in collecting, transporting, and processing end-of-life gear often outweigh the value of the recycled material, making virgin plastic cheaper for manufacturers in many cases[49]. This economic reality is a major barrier to scaling up recycling – it often requires subsidies, incentives, or extended producer responsibility schemes to make it viable. Moreover, recycling infrastructure for these materials is still limited globally – only 10–15% of all plastic waste in Vietnam is currently collected for recycling[50], and fishing gear is a fraction of that.

Lost Gear Retrieval: A significant portion of fishing plastic waste never even reaches shore – it’s lost at sea. An estimated 5.7% of all fishing nets, 8.6% of traps, and nearly 29% of lines are lost into the ocean each year[51]. This ghost gear drifts or sinks, harming marine life[52]. Retrieving it is dangerous and costly, though programs exist (like Global Ghost Gear Initiative and local efforts) to recover nets from the seabed. Any recycling solution must contend with the fact that a lot of gear isn’t readily collected at end of life.

Toward Solutions: Despite challenges, progress is being made. Innovations such as material tracing and buy-back programs are encouraging fishers to bring back old nets. Some governments (including Vietnam’s fisheries authorities) are developing action plans to manage fishing plastic waste[53]. Design for Recycling is gaining attention – e.g., making nets out of one type of polymer, using biodegradable materials for certain gear, or designing gear to have modular easily-separable parts[47]. For instance, trials of biodegradable gillnets (using bio-based polyesters that break down after a certain period) are underway to reduce ghost fishing[54][55]. Recycling success stories, like the Greek initiative where fishers collect plastic and nets which are turned into products like socks, swimwear, and furniture[38][56], show the value of multi-stakeholder collaboration – fishers, NGOs, and recycling companies working together. In Vietnam, projects such as REVFIN are starting to collect discarded nets and demonstrate how they can be transformed into new products[57], raising awareness among local communities. Scaling these efforts will require support: policymakers can help by funding gear collection programs and mandating recycling targets, organizations can facilitate networks to aggregate and process gear waste, and recyclers can invest in technology to handle these plastics more efficiently.