Fisheries for scallops, particularly the great scallop Pecten maximus and to a lesser extent the queen scallop, Aequipecten opercularis, are of considerable economic importance to the United Kingdom (UK) fishing industry. Landings of great scallops have been growing steadily since the 1970s and now consistently place this fishery in the top five most valuable species in the UK. Queen scallop catches have been much more variable over the same time period. Great scallops are predominately taken using Newhaven scallop dredges while queen scallops are mostly captured with otter trawls. A very small percentage (< 5 %) of the great scallop catch is taken by hand by SCUBA divers. There are no catch limits on UK scallop fisheries and licence number restrictions are widely regarded as ineffective. Instead great scallop fisheries are mostly managed through minimum sizes, restrictions on dredge number and seasonal closures in some regions. The use of towed fishing gear (dredges and trawls) is also prohibited in a few small areas, generally for conservation purposes. There are few management measures for queen scallops. UK fisheries for great scallops appear to be stable at present, but there is considerable evidence that their productivity could be improved dramatically by better management. This is because at present the fishery has a number of negative effects on juvenile scallops and provides few spawning refuges for replenishment of stocks. The use of towed fishing gear also damages much of the habitat that is crucial for the settlement and survival of young scallops. The negative effects of towed fishing gear, particularly scallop dredges, on benthic habitats and communities are also of considerable conservation concern. In general, areas subject to high fishing pressure tend to lose structural complexity and have lower biodiversity, species richness, species abundance and rates of benthic production. Biogenic reefs / substrates are the most sensitive to disturbance, followed by sandy / gravel areas. However, sandy / gravel substrates have strong potential for recovery if protected. Shallow, sandy areas subject to high levels of natural disturbance are more resilient to fishing disturbance, but tend to support few scallops and lower diversity of benthic species in general. Scallop fisheries also have a high by-catch of mobile benthic species such as crabs, starfish and some fish species. Although the ecological significance of this bycatch is unclear it has the potential to negatively affect crab fisheries. A new management regime for UK scallop fisheries that provided better protection to key scallop nursery and breeding areas, and maintained healthier benthic ecosystems in general would undoubtedly result in more productive and sustainable fisheries. We therefore examined a series of well managed scallop fisheries from around the world to glean how this might be achieved. These fisheries provide good insight into successful management practices for scallops. In Australia the Queensland scallop fishery was incorporated into the Management of the Great Barrier Reef Marine Park as a whole showing that an ecosystem level approach is feasible. In fisheries such as the US sea scallop where the stock was officially declared overfished, reduction in fishing effort resulted in a return to healthy biomass levels. This has included improvement of the size class structure, a characteristic which would be of great benefit to the UK fishery. Protection of juveniles has proven to be a key factor in several cases and in the French fishery in the Bay of Saint Brieuc it was considered a main reason for their success by increasing the number of virgin (previously undisturbed / captured) scallops and therefore the yield per recruit. Habitat mapping has proven invaluable in most examples for providing information on the location of areas that should be protected for the benefit of juvenile scallop settlement and nursery grounds for other commercial species as well as habitat types that should be protected in their own right to conserve biodiversity. There appear to be two successful ways of implementing these changes. One way is with firm government legislation, which includes tight fishing restrictions that is backed up by a strong enforcement plan. This would include measures such as satellite tracking, patrol boats, on board observers and dockside monitoring. An alternative strategy would be to confer on the fishers a level of ownership of their resource and in some cases this has lead to an industry funded and managed recovery of the resource. This strategy ultimately requires little policing. We suggest a UK management plan primarily based on conferring a level of ownership to fishers operating within the 6 mile zone. This may be met with some resistance in the first instance and we would envisage that a level of enforcement may be required at first. This has been found in other examples but as time passes less enforcement is necessary. This should be set within a framework of zones that should consider all users. We further suggest that all interested parties should be included in an ecosystem level management plan and that the scallop fishery should fit into that plan. Provision should be made to minimize the negative effects of one user group on another such as scallop dredges damaging crabs and tangling in crab pots. The inshore area up to 3 miles should be considered a low impact zone with the 3-6 mile area being a medium impact zone. The low impact zone would include fully protected areas, areas just for static gear fisheries (e.g. crab fishers) and scallop divers and other low impact uses such as recreation. Most of the inshore scallop fleet which uses dredges or trawls should operate within the medium impact zone. The larger vessels in the nomadic offshore fleet should operate outside 6 miles. The key to the success of this scheme for the scallop fishery would be to improve the productivity by increasing spawning stock biomass and improving the size class structure of the populations. Recommended management measures include reducing fishing effort, increasing minimum dredge belly ring size and protecting juveniles and key habitats. If these measures were to be put in place, the UK scallop industry has the potential to provide a much more profitable and stable income for its stakeholders.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)