PILOT PROJECT: REMOVAL OF MARINE LITTER FROM EUROPE'S FOUR REGIONAL SEAS
Toolkit: Derelict Fishing Gear Retrieval, Implementing your project, Involving divers in retrievalSee also: Selection of locations | Timing of retrieval operations | Technical parameters for the vessels | Involving fishermen in retrieval | Reception of DFG at the port | Recycling and disposal | Monitoring DFG | Development of prevention and mitigation measures | Raising awareness of the causes and impact of DFG | Project communication
Divers may undertake the following actions during DFG retrieval operations:
- Removing nets and lines by hand from the seabed by cutting away encrusted or severely entangled lines or netting. Subsequently, the divers can bundle the net including any lead or float. They can use air-lift bags on the netting to keep tension on the net as it is freed from the seabed and to float the released netting to the surface.
- Attaching by hand the grappling hook to the nets and cutting out encrusted or severely entangled nets, such that the winch or reel on the vessel can mechanically pull the net free from the seabed and remove it. Prior to using mechanical force, the divers should return back to the vessel to protect their safety.
- Helping in determining the precise location of nets, such that they can effectively grappled and pulled free and up by the vessel. Using divers can be cheaper than using a remotely operated vehicle (ROV).
Using divers may help you to avoid or to limit the use of mechanical methods, and therefore to reduce the environmental impact of the retrieval operation. Divers may also increase the efficiency and the effectiveness of the retrieval operation, as mechanical force may reduce the amount of gear recovered by inadvertently separating the lead and/or cork lines from the webbing. The webbing, which is the more damaging portion of the net, may be more difficult to locate and remove when separated. All attempts should be made to avoid tearing the lead or float line from the net leaving behind the more environmentally damaging webbing material.
The decision on whether to use divers in you project will depend mainly on the depth and the topography of the seafloor:
- DFG retrieval in shallow waters: To retrieve nets from a sandy sea floor, a vessel and a creeper device are in principle sufficient, and divers are not necessary unless the nets are snagged. However, in shallow water where divers can work effectively, it is preferable to not use the winch or reel on the vessel to mechanically pull the net free from the seabed and/or to remove it. In particular, where the seafloor is rough or rocky, or where there are many artificial snagging sites (such as cables and pipelines on the seafloor) that can catch fishing gear, working with divers can help to minimise the impact of DFG removal on the marine environment and to increase its efficiency and effectiveness.
- DFG retrieval in deeper waters: DFG in deeper waters, where divers cannot work effectively, will have to be retrieved by mechanical means only. To minimise the environmental impact and to enhance the efficiency and the effectiveness, the precise location of the gear should be determined by remote operated vehicle or other effective means. The retrieval requires the use of specific equipment, known as hooks. Different types of hooks have been developed for different types of sea bottom. As the lead organisation, you should ensure fishermen are provided with the adequate hooks.
Clearing wrecks of nets always requires divers. This type of operation is not specifically covered by this Toolkit; however some of the guidance provided may be relevant to wreck cleaning.