How do we stop fishing gear ending up in the ocean?

Commercial fishing gear is one of the most common ocean plastics reported in marine litter surveys.  In the North Highlands it makes up 90% of ocean plastic removed by beach cleaners. [1][2]. Fishing lines, ropes and nets make up 52% of plastic pollution in the Great Pacific Garbage Patch (Figure 1) [3]. Discarded, lost, or abandoned, fishing gear in the marine environment is called Ghost Gear. This gear continues fish and trap animals, entangling and killing marine mammals and damaging vital marine habitats, making it the most deadly form of plastic pollution in the ocean [4]. Reasons for ghost gear becoming such a source of plastic pollution include limited waste management infrastructure, lack of institutional support and appropriate practical arrangements in harbours, for end-of-life fishing gear [5][6]. End-of-life Fishing Gear; worked and worn out commercial fishing gear such as nets and ropes needs to be replaced every three to six months. As of yet there is no government scheme to deal with this problem. NGOs such KIMO, Odyssey Innovation, and Brixham Trawl Makers working with together with manufactures, fishermen, harbours and beach cleaners, are taking the initiative to collect and recycle discarded and end-of-life fishing gear. In this article we will identify the problems caused by ghost gear, and explore solutions to dealing with end-of-life and discarded gear. 

Figure 4
Figure 1. Ocean plastic size spectrum in the GPGP. (a) Plastic mass distribution within the GPGP between size (bars) and type (colours) classes. Plastic type H include pieces of hard plastic, plastic sheet and film, type N encompasses plastic lines, ropes and fishing nets, type P are pre-production plastic pellets, and type F are pieces made of foamed plastics. Whiskers extend from lower to upper estimates per size class, accounting for uncertainties in both monitoring and modelling methods. (b) Measured mass and numerical concentrations of GPGP ocean plastics. Dots represent the mean concentrations, the whiskers and darker shades represent our confidence intervals, and the lighter shades extend from the 5th and 95th percentile of measured concentrations [3].

Ghost Gear

Global seafood consumption has more than doubled in the past 50 years [8], with a knock on effect of increasing the use of commercial fishing gear that can end up abandoned, lost or discarded in the oceans. Ghost gear can entangle marine mammals, seabirds, and turtles causing a slow and painful death through suffocation or exhaustion [9]. In Scotland, entanglement in static fishing gear has been identified as the largest anthropogenic cause of mortality in minke and humpback whales [9]. Ghost gear, particularly plastic fishing nets and ropes take hundreds of years to break down and can continue catching target and non-target species, or ‘ghost fishing’. Ghost fishing incurs a high economic cost on fisheries and the people that depend on fishing for their livelihood; through habitat damage, decreased fish stock and the cost of replacing gear.

Image
Figure 2. adult female minke whale found washed up dead entangles in fishing net on Orkney, Scotland.

Harmful types of fishing gear

Generally fishers don’t want to lose their fishing gear. It is their livelihood and can represent a considerable financial investment. Nevertheless, fishing gear can be abandoned, lost, or discarded in even the best managed fishery. Gillnets, and pots and traps are ranked as the top two most harmful fishing gear. Gillnets are used for passive fishing, they rest in the water acting as a wall that entangles or gills fish. This thin, nylon monofilament fishing gear is highly susceptible to getting lost, and usually is not searched for as it is cheap and easy to replace. A lost gillnet will continue catching fish after it gets lost, and when it loses buoyancy it will still affect the ocean’s seabed [4]. In Scotland, pots and traps are usually metal cages, cased in plastic and covered with plastic nets, which are attached to a buoy and left on the seafloor for passive fishing. They are built to be tough and durable, and last for decades. Traps are baited. When lost at sea they can continue attracting animals, and scavengers that prey on the animals trapped inside. There is the additional risk of entanglement from the buoy. Other high risk fishing gear include hooks and lines which can be a single baited hook or lengthy longlines with thousands of hooks, which if lost at sea can continue catching fish. Trawl and Purse seine nets are ranked as medium risk fishing gear. They are usually expensive hence fishers try to avoid losing them. With technological advancements nowadays they can have marking devices to be able to track them down if lost. However, bottom water trawl nets are more susceptible to getting snagged on the seafloor where they can entangle other species such as crabs, and can affect the seabed through smothering.

Fisheries - Become MSC certified | Marine Stewardship Council
Figure 3 Examples of Fishing gear (clockwise) longlines with hooks, mid-water trawl and bottom water trawl

Surface trawls are typically made of polypropylene which is lighter than water. During fishing operations a section of net might suffer damage and needs to be cut apart. Repair segments left on the working deck can unintentionally be lost to sea during stormy conditions or when the next haul is brought up. These lost repair segments, together with torn fragments tend to float on the surface. They eventually get washed ashore. Larger fragments are a potential entanglement hazard to seals and sea birds, while smaller fragments can be ingested by marine animals and sea birds [12]. Damaged nets and repair cut-off are the most common form of plastic pollution found by beaching cleaners in the Highlands [2] [13].

Figure 4. Three gannets entangled in a fishing rope found on Balnakeil Beach, Durness May 2017.

End-of-life Fishing Gear

In the UK there is no law that requires vessels to take-back or recycle damaged or end-of-life fishing gear. Waste management is the responsibility of individual Harbour Masters and is not consistent across harbours. In some instances fishermen pay for containers directly or pay a fee to harbour masters to manage waste [14]. Once landed end-of-life gear is either sent to landfill, burnt, incinerated or left in piles in harbours and ports. In Scotland 20 harbours take part in KIMO Scotland’s Fishing For Litter Scheme (FFLS) [15]. Participating vessels are given hard wearing bags to collect marine litter caught in nets during normal fishing activities. Full bags are deposited on the quayside in participating harbours and moved by harbour staff to a dedicated skip which is then sent to landfill. FFLS costs the harbour £1,000 per year. It has successfully removed hundreds of tonnes of discarded gear from the ocean and mitigated end-of-life fishing gear entering the ocean. However, it is an EU funded scheme, and the Scottish government has not yet committed to taking over the cost. The project currently costs around £100,000 per year to run, with the biggest single cost being the disposal of the waste collected [16]. In the past KIMO organised the collection of end-of-life and discarded gear picked up by FFL from Peterhead, Scrabster and Ullapool harbours [17], which was sent to Plastix Global in Denmark for recycling. This scheme ended back in 2016 due to collection issues. 

Fishing for Litter: Working with fishermen to clean our seas – KIMO
Figure 5. KIMO Fishing For Litter

Recycling Fishing Gear

Recycling of end-of-life and discarded gear can have some challenges. Removing discarded gear from beaches is very labour intensive. Fishing gear is constructed of multiple types of plastic or polymers. Nets and ropes can be made of nylon or polypropylene (PP), while rigid items like oil drums and fish boxes are made from High Density Polyethylene (HDPE). It is essential to separate items into individual polymers, because polymers have different properties and mixing them would compromise the quality of the final recycled plastic. Cleaning, identification and sorting of mixed polymers can work out more expensive than sending them to landfill [15].

Figure 6. Large trawl net recovered from a beach in Durness by Plastic@Bay.

There is no ocean plastic recycling facility in the U.K. Harbours or NGOs that recycle fishing gear send it abroad to either Aquifil in Solvenia or Plastix Global in Denmark. Aquifil only take nylon nets, which are chemically recycled into Econyl yarn [16] and can used to make swimwear, running shoes and carpets, for example. Plastix recycle a range of ocean plastic including, fishing nets, trawls and rigid plastics into quality recycled plastic material (rPM) also called pellets [11], which have been used to create finished goods including, but not limited to, compost bins, recycling crates, outdoor furniture, kayaks and footwear. Collection is free for waste consignments over 30 tonnes. This system is not suitable for small harbours with insufficient storage space to stock pile large quantities of nets. Environmentally conscious company Odyssey Innovation based in South West England have partnered with Plastix to make kayaks out of recycled ocean plastic. Odyssey collect end-of-life gear from Newquay Harbour and St Ives Harbour, and a centralised drop off point for small harbours, as well as ocean plastic from beach cleans to ship to Denmark.

Turning unwanted nets into ocean-going kayaks - Exeter City Council News
Figure 7. Odyssey Innovation collecting large fishing nets from a harbour for recycling.

In Scotland, Plastic@Bay are at the forefront of low-tech ocean plastic recycling. We are the only manufacturing company to collect, clean, sort, shred and recycle ocean plastic in-house using low-tech extrusion and injection mould machines. We manufacture tiles, beams, clocks, coasters and jewelry, and sell shredded nets and ropes, and HPDE from fish crates, oil drums and fish farm pipes to small scale plastic manufacturers.

Figure 8. Beams made from recycled ocean plastic by Plastic@Bay

Our leadership in the field of ocean plastic recycling is being recognised. In 2021, Plastic@Bay will receive national funding to built a low tech continuous production extrusion machine capable of making non-load bearing construction material, and to design affordable low-tech plastic recycling facilities to recycle end-of-life fishing gear directly in harbours. The aim is create a sustainable enterprise that can be replicated in communities adversely affected by ocean plastic pollution.

Details of our new project will be announced 8th March 2021. Stay tuned.

Further Reading

World Wildlife Association Report on Ghost Gear

Scottish Governments report on Commercial Fishing Gear

Global Ghost Gear Initiative Best Practice Framework for the Management of Fishing Gear