Plastic has been proven to impose detrimental effects on at least 267 species around the world. This includes the following: 86% of sea turtle species, 44% of seabird species and 43% of all mammalian species. Animals are mostly harmed through ingestion (reducing stomach capacity, hindering growth, internal injuries, intestinal blockage), entanglement and subsequent strangulation ^[1][41]. Moreover, 340 original publications reported encounters between marine debris and marine animals ^[2][42]. At least 17% of those affected by entanglement and ingestion were listed as threatened or near threatened ^[3][43].

The number of species proven to be negatively affected by derelict plastic debris has doubled since 1997. Ghost gear is one of the most deadly forms of marine plastic debris ^[4][44]. It tends to continue to catch animals as long as it retains proper integrity ^[5][45]. This usually occurs during the first year after the loss of ghost gear, but there are observed types of fishing nets continuing to capture animals even decades after being lost ^[6][46]. Even though most fishing gear is designed to capture animals in a selective way, it is known by now that when lost, fishing gear can capture animals indiscriminately. It has been documented that in the Salish Sea, more than 260 species have been observed to get entangled and killed by lost salmon gillnets. It has also been estimated that the 4500 nets removed from 2002 to 2009 might have killed more than 2.5 million marine vertebrates, 800,000 fish and 20,000 seabirds ^[7][47]. Over 5400 animals from 40 different species of marine mammals, reptiles and elasmobranchs were entangled in ghost fishing nets ^[8][25].

Out of all marine mammals, seals and sea lions appeared to be the most endangered species by entanglement. In Australia, it has been estimated that 1500 sea lions die from entanglement every year ^[9][48]. In the Sea of Okhotsk, the most common victims of entanglement were young males, as a consequence of their natural curiosity and playful behavior. Additionally, the rotation of the body is a natural panic reaction that causes more entanglement for long periods. Most of the plastic debris found on sea lions was associated with nearby fishing ^[10][49]. There is evidence that even the relatively small entanglement rate of 0.4% of the northern fur seals is serious enough to affect the whole population. This is due to the disproportionate effect on individuals of fertile age ^[11][50].

Marine plastic in the form of net, rope, monofilament line and packaging bands can cause entanglement in a wide range of pinniped species. There is a noticeable potential for an acute impact on individuals by starvation and highly restrictive entanglement. Some animals live with chronic deep wounds for months or even years. Chronic wounds may cause a deep infection, leading to the premature death of an individual. The result of marine debris entanglement is the first and foremost suffering of animals through wounding, amputation or ingestion. This often goes hidden and unreported. Fur seals, monk seals, California sea lions, grey seals and common seals are the most likely species to be affected by entanglement ^[12][51]. It has been found that over the last two decades, entanglement records of seabirds have increased from 16% to 25%.

Lost fishing gear also damages important nearshore habitats, including seagrass beds, coral reefs and mangroves ^[13][52]. Lost fishing gear break corals, damage vegetation, build up sediments and impedes access to specific habitats ^[14][53]. It is considered likely that plastic on the seabed alters the dynamics of the entire ecosystem. Upon covering the seafloor, plastic sheets inhibit gas exchange, leading to low oxygen levels and the formation of artificial hand grounds, creating problems of burying creatures ^[15][54]. However, some organisms are able to adjust themselves to these conditions. Floating plastic debris was used by a variety of microorganisms as a newly created habitat ^[16][55]. Plastic debris also attracts fish or sea turtles to aggregate below its surface and follow the drifting material ^[17][56]. Damage to marine and coastal ecosystems ^[18][57] is challenging to calculate, but it has been proposed that a 1% decline in annual ecosystem services could equal a loss of USD 500 billion in global ecosystem benefits annually ^[19][58].

Plastic microparticles in the marine environment are being absorbed by small organisms at the base of the food chain. They are subsequently transported further up the food chain as the prey is eaten by the predator. Higher and higher concentrations are reached all the way to the top predator species. This process is called bioaccumulation and has an effect on human lives upon the consumption of fish and other seafood. Chemicals from oceanic plastics have been detected in human bodies as well ^[20][59].

On average, a human body absorbs approx. 52,000 particles of microplastic by ingestion per year. It is under investigation exactly where in the body it tends to accumulate the most and what kind of negative effect it would have on human health. Depending on the known impact of plastic on human beings, it is supposed that it may contribute to neurodevelopmental disorders, metabolic, respiratory and cardiovascular diseases as well as decreased antibody response to vaccines ^[21][60].

Macroplastics have the potential to reduce the efficiency and productivity of commercial fisheries. The most important impact occurs through ghost fishing by ALDFG ^[22][5]. Ghost nets may get caught up and damage the machinery of the fishing boats ^[23][61]. Fishing operations near the coastline may have livestock as the nets are being picked up by the animals upon reaching shore.

According to experiments on abandoned and lost crab traps, an estimated 12,193 traps are lost annually in the Washington waters of the Salish Sea. Lost traps still show some catch rate, which results in animals being caught but never picked up. The annual Dungeness crab loss was estimated to be 4.5% of the value of harvest, translating into a value of USD 744,296. Unfortunately, the value of saved crabs is lower than the cost of removal. Nevertheless, the best solution could be to modify the trap design, which might reduce the mortality rate and negative impact on the abundance of crabs ^[24][62].

However, studies on the removal of derelict blue crab pots in the Chesapeake Bay showed more promising results. This may encourage fishers to organize an additional removal. Removing 34,408 derelict pots led to significant gains in gear efficiency and an additional 27% increase in income (USD 21.3 million). Global analysis shows that removing less than 10% of derelict pots and traps could result in a recovery of USD 831 million. Removing ALDFG will not only save marine biota but also appear to be profitable and sustainable for governments and communities whose livelihoods depend on income from the ocean ^[25][63].

In 2015 costs induced by derelict fishing gear on fisheries and aquaculture have been estimated at USD 1.47 billion. On transport and shipbuilding at USD 2.95 billion, which gave 13.4% and 27% of annual costs respectively ^[26][64]. In the Adriatic and Ionian Seas, the annual loss due to derelict fishing gear for the fishing sector was estimated at USD 21.86 million ^[27][65].

Marine plastic debris on beaches and in touristic marine environments (for example, coral reefs) presents a serious visual and aesthetic problem. The presence of litter has a significant negative impact on recreational experiences and overall beach enjoyment ^[28][66]. Visitors actively avoid spending time on polluted parts of the coast ^[29][67]. This generates lots of opportunities for industries because tourists favor alternative, less polluted locations, reducing income for businesses operated at less visited beaches ^[30][2].

The direct cost impact of marine debris on tourism has been estimated in 2015 at USD 6.41 billion, which is 59.2% of the total damage caused by derelict plastic ^[26][64]. In the region of the Adriatic Sea, the tourism sector lost an average of USD 6833 per year and harbors needed to spend USD 10,238 on managing marine litter ^[27][65]. In Orange Country, California, marine litter was reduced by 25%. This saved additional costs for visitors, who no longer needed to travel further in their search for non-polluted beaches ^[31][68].

Marine debris can present navigational hazards to ships at sea by entangled propellers, blocked water intakes and collisions with floating objects. Especially when the weather conditions are bad, the entanglement of propellers can significantly reduce stability and maneuverability ^[32][69]. Derelict fishing gear causes economic costs here as well, as sometimes changes in routes may be needed to avoid a collision. This may have a significant influence, especially in areas with heavy marine traffic ^[33][70].

Different economic costs of pollution can be divided into prevention, remediation and damage costs. Prevention costs are the lowest and involve a range of actions organized by civil society organizations, governments and industries to reduce the amount of plastic litter entering the oceans to avoid damage and remediation costs in the future ^[30][2]. The annual global economic cost of marine plastic pollution is estimated to be at least USD 6–19 billion globally ^[34][71]. The cost of cleaning coasts could be reduced by a proper prevention policy ^[27][65]. The total cost of damage in 2015 in the region of the Asia-Pacific Economic Cooperation (APEC) has been estimated at USD 10.8 billion annually ^[26][64]. Moreover, the estimated cost of removing marine plastic from a remote atoll in the Seychelles was USD 4.68 million with 18,000 h of labor ^[35][72]. In the Republic of Korea, USD 282 million was sent over five years to remove plastic litter ^[36][73]. During a period of eight years, Japan spent USD 450 million on ocean plastic removal ^[37][74].

These damage costs, including lost opportunity costs and indirect costs, could be significantly reduced by preventing plastic from leaking into the environment. The worsening aesthetic of beaches polluted by waste reduces the number of tourists and income. Not only are fisheries affected (covering costs of damage caused by derelict fishing gear), but also land-based agricultural centers are affected by plastic litter blown onto beaches. Proper municipal clean-up practices are promising opportunities for the prevention of expenditure ^[30][2].

The presence of ALDFG in marine environments is due to the following: irresponsible fishing practices, inadequate access to recycling facilities, low return prices for consumable plastic and a high cost of recycling ^[38][75]. Mechanical recycling is the simplest process. It involves following the following steps: sorting, cleaning, granulation, drying, melting, extrusion and pelletizing ^[39][35]. What is worth mentioning is that developing countries, such as Brazil, China and India, have high plastic recycling rates, between 20% and 60% ^[40][76]. In Australia and the United States, plastic recycling is low as follows: 10%–15%, whereas in Western Europe and Japan, recycling rates for plastic are around 25%–30% ^[40][76].

Technically, it is possible to separate most plastics into recognizable streams, but not all plastic streams are mechanically processable. It depends on the chemical and mechanical behavior as well as on the thermal properties. Only thermoplastic polymers (for example, polyethylene, polypropylene and polyester) are mechanically recyclable ^[41][77]. An alternative to mechanical recycling is chemical recycling, which produces plastic feedstock that can replace virgin plastic ^[42][78].

The main challenges for the circular fishing gear design are associated with the following: low utility of current materials, high level of mixing of different materials, lack of legal obligations for recycling from local authorities, lack of support and high cost of alternatives, low use of collection points in harbors and high organic contamination, which reduces the recyclability ^[43][79].

The most important practice for addressing the problem effectively is the prevention of gear loss. This is the ultimate goal of any progressive ghost gear program ^[44][80]. That is why it is aimed at the temporal separation of different gears, including the prohibition of high-risk types. For example, the Western Central Pacific Fisheries Commission prohibited large-scale driftnets. Additional separation of individual rope and net types is highly beneficial for all processing stages and the requirement to obtain uniform samples for material recycling ^[44][80].

Moreover, innovative solutions to end-of-life fishing gear promise to reduce the extent of lost fishing gear. Current actions taken by the European Commission have established a progressive goal of abandoned fishing net collection rate of 50% and a 15% recycling target, both to be met by 2025 ^[44][80]. There are many removal programs around the world that are focusing on different strategies of collection or cleaning the oceans. Some of them are highly specific. For example, the Northwest Straits Foundation’s program is an initiative focused on the rapid removal of newly lost gillnets ^[44][80]. Other recommendations for the prevention of ALDFG are mostly focused on industry and governments. The great interest should be focused on solutions aiming at hot spot plastic areas. Mapping historic, ongoing and possible ALDFG data collection can significantly improve ocean cleaning practices and prevent the accumulation of plastic litter ^[45][81].

Among the most important premises for establishing a recycling economy is creating international recycling standards, especially for mechanical recycling, as it is the most well-developed approach in terms of industrial feasibility ^[46][82]. One example is the creation of the European Strategy for Plastics in a Circular Economy where the design and production industry meet the needs of reuse, repair and recycling ^[43][79].

While eroding, polymeric chains decompose and release various chemical species. One of the most used materials is nylon 6, which was subjected to thermal analysis. The material was decomposed into volatile monomers at a temperature of approx. 400 °C at different heating rates (5, 15, 20 and 30 °C/min) ^[47][83]. Results showed that the decomposition of nylon 6 corresponds to a spectrum of caprolactam-based compounds during the most intense stage of decomposition. Pyrolysis of nylon 6 results in the reduction of the material into monomers, indicating the potential for the production of caprolactam. This also implies that waste nets can be converted to monomers via pyrolysis.

Available polymers have limited recyclability potential. Because of carbon-carbon backbone strength, depolymerization to monomers is prevented ^[48][84]. Polymers redesigned with ester backbones may be better suited for controlled chemical depolymerization. However, it may also be suitable for biological processing in managed systems, such as individual composting ^[48][84]. Even if the polymer satisfies the criteria for use and end-of-life, it is important to prepare a recoverable, sortable and separable product design. An example is the availability of the APR Design Guide for Plastic Recyclability, which is currently used in plastic-based packaging.

Promising R&D routes for establishing biodegradable fishing net materials often comprise blending mutually compatible biodegradable polymers. A unique R&D route for establishing a marine-degradable fishing net is the incorporation of photocatalyzable ether linkages along the polymer backbone architecture. Other R&D routes for establishing degradable fishing nets may promote biocatalytic degradation by various mechanisms.

However, designing photodegradable or biodegradable materials cannot be the sole solution as the environmental hazard remains for extended durations. Instead, a strong societal need exists for economically attractive “fishing net return schemes” (analogous to plastic bottle deposit schemes) for occupations fishers, providing an economic incentive to minimize abandoned, lost, or discarded fishing gear. The success of such economic return schemes would in the future enable the possibility of more conventional material mixing technologies for upgrading partially biodegraded fish nets. Such material mixing technologies would benefit from new rapid “multidimensional molecular characterization” technology to quantify, on a batch level, the amount of biodegradation experienced on each “homogenous” batch of recovered fishing nets. Such “multidimensional molecular characterization” would incorporate a quantified measure of chemical functional group polydispersity, enabling more accurate predictions of the mechanical properties of recycled polymer mixtures.

Several research institutions have taken the challenge of finding new opportunities for recycled fishing nets and therefore getting them closer to the circular economy. Unfortunately, recycled polyolefin resins from fishing nets seem to have poor properties due to the presence of contamination. The blend of derelict PE nets with different types of virgin resins showed a potential for usage in packaging. Even though the created composites have certain limitations, it was possible to meet the required elongation at break as well as impact strength and environmental stress cracking resistance. With a properly chosen virgin resin, it is possible to use the plastic from fishing nets in packaging ^[49][85].

Interesting results were presented with the usage of recycled nylon fibers as tensile reinforcement of cementitious mortars. A significant increase in tensile strength and toughness was observed. Unreinforced material achieved approx. 35% lower tensile strength and up to 13 times lower toughness ^[50][86]. Moreover, it was discovered that the fibers of nylon fishing nets helped transfer stress through cracks and distribute stress by transforming a single wide crack into several smaller ones ^[51][87].

Obtaining the oil from the waste fishing net as a substitute for diesel fuel has been another, albeit uncommon investigation. This too, achieved some promising results. Oil from waste fishing nets possesses excellent fuel properties, with a calorific value of 44,450 kJ/kg (higher than diesel by 1.48%). Additionally, it works on a diesel engine without requiring any engine modifications. Nevertheless, the brake thermal efficiency decreased. Brake-specific fuel consumption increased, and so did engine emissions ^[52][88]. This is still, however, an idea worth further investigation as it may prove useful for retrieving fossil fuels.

In general, governments and international and local companies are aware of the negative impact of ALDFG on both the environment and the economy. To solve this problem, research on creating a new product by using the waste from fishing nets has already started. Currently, there are already being developed interesting solutions for transforming fishing ropes into nylon yarn for the production of clothes and carpets ^[53][89]. One of the many examples of using nylon fibers for clothing production is a Polish company named Gabriella. In 2021 designed tights consisting of 70% of oceanic wastes ^[54][90]. It has been proven that it is both possible and profitable to create sustainable and aesthetically pleasing products.

With the common initiative of the foundation MARE and the jewelry design company ORSKA, derelict fishing nets from the Baltic Sea were used for creating a new collection line. Ground fishing fibers were mixed with granules of recycled plastic that had undergone a thermal treatment, which resulted in the material used for creating the New Stone design line ^[55][91]. The Stone was created with the help of Tomasz Rygalik, the owner and designer of the Studio Rygalik company. His previous work shows the possibility of designing products out of plastic blends. He has created a material called Boomplastic, which has found its use in the creation of outdoor furniture—creating a garden bench called Circula. Boomplastic is a blend of polypropylene and colorful flakes obtained from polypropylene packages and bottle caps. The transparent matrix came from the grinding of damaged polypropylene bottles and cups ^[56][92].

Another brand called Karun started to create its products from plastic waste over 10 years ago. Their material is called Econyl, which is a nylon coming from ghost-fighting nets found in the ocean. Out of this plastic, there has been created spectacle frames, now available around the world ^[57][93]. Additionally, in 2022, the design company Design Milk from Sweden presented the innovative project of the 3D printed chair, using recycled fishing nets and wood fiber ^[58][94]. The creation of the Kelp Chair ^[58][94] prevented fishing nets from ending up in the depths of the Baltic Sea and instead turned them into new material. Promising results from research and usage of these materials create optimism for the further development of this field. The examples shown above indicate that recycling ALDFG and turning it into new material might become an economically profitable field. These new plastic types might be able to reduce the amount of virgin plastic entering the environment as well as limit costs connected to marine plastic debris.