Lost and discarded fishing gear - Technologies and practices for detection and retrieval

Nils-Roar Hareide

Runde Environmental Centre, Rundavegen 237, 6096 Runde, Norway  

ABSTRACT

Sea currents are spreading plastic objects over large areas. At the west coast of Norway, The Atlantic Current and the Norwegian Coastal Current are transporting plastic waste to the shores of the West Coast of Norway. Plastic in Norwegian shores come from different sources, from all types of human activities such as fisheries, aquaculture, roadbuilding, maritime transport, households and fish processing.

In fisheries and aquaculture the lost and discarded gear can be divided into two fractions fractions , namely the floating and sinking fishing gear. The floating nets and ropes come are mostly made of polyethylene and polypropylene . Sinking ropes are made of polyester and nylon. The floating fraction is carried by the sea currents and is spread all along the coast and the heavy parts are sinking to the sea bothom.

The shore line can be monitored by drones and satellites. However, the plastic that has grown into the soil is difficult to monitor, and to clean up without crushing and make more micro plastic is a big problem

The coast line is very long and in many areas there is no road nearby. Volunteers are doing a great job cleaning he shores. However, the transport and logistics are not developed for such a big operation.

Very much of the fishing gear found on the shores are discarded (80-90% by number). These are often small parts of ropes and nets that have been cut of during the work on mending and repairing nets. Plastic bands from boxes for bait are, fish boxes and waist from the galley are also plastic waste discarded from the Fishing Fleets. On the sea floor the so called ghost nets are a big problem. Nets and pots are lost and continues to catch fish. This is both a plastic pollution problem and also an uncontrolled mortality for fish and crab stocks.

In Norway good and precise reporting is found to be vital. There has been an increasing development for digital reporting. Different technologies have been tested for mapping and identifying nets, such as sonars, echo sounders, side scan sonars , ROVs and AUVs. These technologies have proven to be very useful, but also expensive.

There are systems that are under developing for detecting nets by means of transponders on the nets. This technology is expensive, especially for small fishing vessels. To go out searching for the nets is expensive. This could be done by autonomous vehicles either surface or subsea.

The dominant technology is to use different types of creepers (hooks and anchers). There is a need for developing these technologies in order to make them more precise and effective. Heavy creepers are also a problem for the sea bottom and coral.

Recommendations

• Technology development is needed for
• Monitoring of plastic on both land and sea
• Clean up operations on shore
• Clean up operations off shore
• Detecting nets
• New creeper technology

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