Article produced by Seafish – the authority on seafood.
- In 2010, the UK fleet landed 42,700 tonnes of scallops, worth an estimated £54.4million, into UK ports (Marine Management Organisation statistics). Approximately 60% of UK landed scallops are exported to European countries, particularly France, where UK scallops are held in high regard. Over 98% of UK landed scallops are caught by vessels using towed fishing gear. There is a misconception that scallop fishermen tow dredges or trawls over every bit of the sea bed. In fact, fishermen know where the species are found and make rationale decisions about where to go scallop fishing.
- Scallops are a highly prized type of shellfish, of which there are more than 40 commercial species worldwide. The UK has two main commercial species: king (Pecten maximus) and queen (Aequipecten opercularis) scallops. These are either harvested from wild or cultivated at sea in nets suspended either in the water column or on the seabed.
- The principal environmental concern with fishing for scallops relates to some of the methods of harvest. Three are traditionally used: diving, trawling and dredging. Diving involves collecting scallops by hand from the seabed. Trawling – such as the summer trawl fishery for Manx queen scallops – is generally done on relatively smooth seabeds and results in relatively low seabed impact and low by-catches of other species such as fish. The third method is dredging. All types of dredging involve dragging some form of heavy metal frame along the seabed. These dredges may also have teeth which penetrate the surface of the seabed to dig out king scallops that burrow into the sediment.
- It is well known that scallop dredges can have a significant impact on the marine ecosystem. However, the severity and extent of the impact depends also on the nature of the seabed and the overlying water column. Just as with other forms of bottomtrawl, dredging may not necessarily be destructive if used in areas with ‘high energy’ seabeds (soft or sandy ones that naturally change all the time as a result of normal tide, current and wave action). The key consideration is the resilience of the habitat to scallop dredging. The faster the recovery rate of the animals and plants that live in the affected seabed, the more tolerant it will be to scallop dredging.
- Dredging must be done only with full understanding of the fisheries concerned, together with a practical application of mitigating measures. For instance, bottom imaging and seabed mapping technology can help to precisely target scallop beds and avoid other habitats and species. Changes in mesh size can increase selectivity, to allow juvenile scallops to escape, and changing the design of the gear may reduce its impact on the seabed environment. These are all active initiatives currently being pursued by Seafish together with the fishing industry.
- Further management measures may involve harvesting controls (such as closed seasons and effort limitation) plus longer term area closures to increase yield or protect the spawning stock. Particularly special and vulnerable habitats are protected through Marine Protection Areas, and are entirely closed to certain types of fishing.
- MSC has accredited dredged scallops in Shetland so they can be sustainably harvested in a manner that is sympathetic to the surrounding environment. The industry is working towards other accredited schemes including the Red Bag case study and MSC has also accredited the Isle of Man summery trawl fishery for queen scallops (www.fisheries-conservation.bangor.ac.uk).
- Dive-caught scallops are not a wholly practical alternative to traditionally-caught scallops as they could never fulfil consumer demand, representing as they do, only 3- 5% of the current market, and even then only at the top end. What’s more, divers can only operate in restricted depths due to limitations imposed by the physiology of diving.
- There are plenty of responsible hand-divers, but the practice is widely unregulated, and can therefore in its own rights cause problems. Hand-dived scallops should be sold through processors that routinely undertake sampling of scallops for toxins.
- Improvements in the management and approach taken with dredging need to be balanced with an increase in responsibility and accountability of hand-divers, with both taking into account their impacts on the environment. Seafish supports improved management in both sectors, as both have their place in providing food and maintaining a valuable export market for the UK.
For more information:
Seafish’s Responsible Sourcing Guide for scallops: