Scallops live on the seabed and the vast majority are caught using scallop dredges. Scallop populations in Cornish waters are poorly studied but are unlikely to be endangered due to the rapid growth of this species. The impact of scallop dredging on the environment is the main concern with this fishery as the heavy toothed dredges used dig into the sea bed and disturb and damage habitats and species. Cornwall Inshore Fisheries and Conservation Authority have placed many restrictions on scallopers in Cornish waters making our waters among the best managed for scalloping in the UK. There is still room for improvement and with increased fisheries led management of productive scallop grounds the future of this fishery could be far more sustainable.
Scallops are bivalve molluscs. They live on soft seabeds; sand mud and gravel. They filter feed on plankton and detritus. Scallops are able to move by rapidly closing their shell which forces jets of water out of the back of the shell and propels them along.
When a scallop is resting on the seabed and feeding its shell opens by up to 2 centimetres and the mantle with thousands of tentacles is visible. A ring of eyes all around the shell further improve the sensory ability of scallops to detect predators.
Scallops are hermaphrodites (i.e. both male and female) and become fully mature at about 3 years old (80 to 90mm in length). Spawning occurs in the warmer months, from April to September, and a three year old scallop can produce between 15 and 21 million eggs each year! (Marlin)The species can grow to more than 20cm in length and live for more than 20 years, although average sizes are in the range of 10-16cm.
Due to rapid growth and high reproductive rate scallops have a low vulnerability to fishing pressure 26% (Cheung et al 2005, source www.sealifebase.org)
Stocks of scallops in UK waters are understudied but stock landings have remained relatively constant for many years. A recent large scale government funded research project led by CEFAS called the red bag scheme concluded that there is still insufficient data to say that stocks are being sustainably harvested in Cornish waters. It is thought that scallop stocks in the western channel are likely to be below MSY (Maximum sustainable yield). MPAs may have a positive effect by creating closed areas for scalloping. Project inshore used a Risk based framework methodology to analyse scallop fisheries in the South west and estimate that there is a high risk for this stock. The Seafish responsible sourcing guide states that Periodic intensive fishing by large (>15m) ‘nomadic’ boats from England and Scotland in recent years has threatened the viability of small-scale inshore fleets that rely on local beds.
This is a highly regulated fishery but there is currently no quota providing a cap on quantities of scallops caught. There are indirect limits through gear and effort restrictions and a minimum landing size.
In CIFCA waters -Vessels larger than 10m fishing in the English channel are restricted by KW days and a 7pm-7am curfew applies within Cornwall and Devon IFCAS.
Effort is capped through restrictive licensing and local Inshore Fishery Conservation Authority (IFCA) permit. Within Cornish waters CIFCA have placed a restriction on the number of dredges used per boat inside 6 mile limit of 12 per vessel and restrictions on mesh size on dredges and length of dredge bar.
There are 40 vessels fishing in Devon and Cornish waters that have Vessel Monitoring Systems (VMS) fitted voluntarily either to engage in the Lyme Bay pilot project or by those vessels that fish nomadically in Welsh waters where its use is compulsory. VMS provides fisheries management agencies with accurate information about the location and activity of regulated fishing vessels and is a cost effective tool for the successful monitoring, control and surveillance of fisheries activities. The length and power of vessels scalloping within Cornish IFCA waters is restricted to 18.28 m (60ft) and 221 kw (300hp). There are currently no industry led seasonal closures or restricted areas for scallopers in Cornish waters but these have proven to be effective in other parts of the UK for management of scallop stocks and habitats. A Voluntary Scalloping Good practice guide has been developed by the Scallop association and many local boats adhere to this
The majority of scallops (98%) are caught using scallop dredges. A small quantity are collected by divers. Scallop dredges are steel framed nets that are pulled along the seabed. Spring loaded teeth act like a rake cutting into the seabed and flipping scallops up and into a net. The teeth can hinge backwards to prevent the dredge snagging on the seabed if it hits rock or wreckage. Use of these ‘Newhaven dredges’ have a well-documented impact on the seabed (Sewell and Hiscock) particularly the first time an area is fished but in some areas which have already been dredged the additional impact can be argued as far less. Rocky grounds and reefs are avoided. Scallops are also collected by divers in shallow waters.
Cheung, W.W.L., T.J. Pitcher and D. Pauly 2005 A fuzzy logic expert system to estimate intrinsic extinction vulnerabilities of marine fishes to fishing. Biol. Conserv. 124:97-111 source www.Sealifebase.org
SEAFISH Responsible Sourcing Guide: Scallops. Version 3 – January 2013
CEFAS Red bag scheme final report July 2014
Ecological Risk Assessment of the effects of fishing for South West fisheries; ICES Divisions VII e,f,g &h Seafish 2014
UK scallop fishery good practice guide – Shellfish association and Seafish industry authority http://www.seafish.org/media/Publications/UK_Scallop_Industry_Good_Practice_Guide_for_consult.pdf