CENTRE FOR ENVIRONMENT, FISHERIES AND AQUACULTURE SCI ENCE SHELLFISH NEWS NUMBER 15 MAY 2003 CEFAS is an Executive Agency of the Department for Environment, Food and Rural Affairs (Defra) 1 * ‘SHELLFISH NEWS’ is produced and edited by CEFAS on behalf of Defra, Fisheries II Division. * It is published twice yearly (May and November) as a service to the British shellfi sh farming and harvesting industry. * Copies are available free, on request to the editor. * Articles, news and comment relating to shellfi sh farming and harvesting are welcomed and should be sent to the editor. The deadline for the next issue is Friday 3rd October 2003. * The views expressed in this issue are those of the contributors and are not necessarily the views of the editors, CEFAS or of Defra. The editors reserve the right to edit articles and other contributions. Editor: Ian Laing CEFAS Weymouth Laboratory Barrack Road The Nothe Weymouth Dorset DT4 8UB Tel: 01305 206711 (Fax: 206601) email: [email protected] Assistant Editor: Denis Glasscock CEFAS Lowestoft Laboratory Pakefi eld Road Lowestoft Suffolk NR33 0HT Tel: 01502 524304 (Fax: 513865) email: [email protected] www.cefas.co.uk © Crown copyright, 2003 Requests for reproduction of material from this issue should be addressed to CEFAS 2 CONTENTS Page Articles Conwy mussels - a history ...............................................................................................................5 Too close a shave for razor clams? .................................................................................................7 Technological advances in fi sheries monitoring: electronic log books in the crab fi shery ...............9 Scallop shucking method can reduce gonad ASP levels ...............................................................10 Towards sustainable mussel cultivation.........................................................................................12 High pressure processing ..............................................................................................................15 The Loch Ryan native oyster fi shery..............................................................................................17 Native oyster beds in Wales...........................................................................................................19 Oyster restoration in Chesapeake Bay ..........................................................................................20 An evaluation of the lobster fi shery in Sussex ~ the effectiveness of current stock protection measures....................................................................................................................21 French turn slipper limpets into fertiliser ........................................................................................24 Environmental impacts of freshwater prawn farming in Bangladesh .............................................25 Announcements UK microbiological laboratories undertaking shellfi sh testing ........................................................28 Morley acts to protect Shellfi sh Stocks ..........................................................................................29 Strategic framework for aquaculture in Scotland ...........................................................................29 Scottish harmful algal blooms study...............................................................................................30 Seafood Week 2003.......................................................................................................................31 Schools’ seafood website unveiled ................................................................................................32 Seafi sh appoints new Aquaculture Offi cer .....................................................................................32 Researchers discover new aquaculture antibiotic..........................................................................32 News from the Trade Associations SAGB .............................................................................................................................................33 ASSG .............................................................................................................................................33 Monitoring reports The marine biotoxin monitoring programmes for England and Wales : 2002-2003 .......................37 The marine biotoxin monitoring programmes for Scotland: 2002-2003 .........................................39 The 2002 Bonamia and Marteilia sampling programme in the UK.................................................42 Research News.......................................................................................................................................43 Shellfi sh in the Press .............................................................................................................................54 Information File Where can I get help or advice? ....................................................................................................62 Useful Publications.........................................................................................................................63 3 4 ARTICLES CONWY MUSSELS - A HISTORY Mark Hughes The Pearl Fishers When pearl fi shers became mussel men and gatherers of mussels as food is uncertain, but different techniques At one time, two types of mussel were found in the were used according to the position of the shellfi sh beds. Conwy River; Mya margaritifera, called Cragen y Diluw in Welsh, and Mytilus edulis or Cragen Las. Shore gathering The former, famed for producing pearls, was found higher up the river near the spa town of Trefriw. The In a process described as ‘hel ar y lan’ (collection on pearls produced by these mussels were considered the shore), pickers were dropped off at their stations by some hardly inferior to oriental ones. The harvest in the estuary by the family boat. Here they used a no doubt attracted the Romans around 80 AD to this small knife called a twca; a spoon shaped blade made fi ne part of the world. The Roman writer and historian by a local blacksmith to the gatherer’s individual Pliny believed that pearls from Conwy were set in a specifi cations, to prise the mussels away from the rocks. breastplate dedicated to the Temple of Venus in Rome The length of the blade of the twca, according to one by Julius Caesar. gatherer, equalled the ‘length of the inside of the middle fi nger’. The twca was held in the right hand and three Conwy pearls are also mentioned in Edmund Spenser’s or four mussels pulled away from the rocks by the left poem ‘Fairie Queene’ of 1590: hand and transferred to a willow or wire basket placed Conway, which out of the streame doth send nearby. Three baskets constituted a bag-full and the Plenty of pearls to decke his dames withal. shore gatherers, usually women, bound their hands with rags to prevent cutting from the sharp mussel shells. Catherine, Queen of Charles II, was presented with a Before the men returned in their boats the bagged, shore Conwy pearl by Sir Richard Wynne of Gwydir, and collected mussels were carried to Conwy and sorted on placed in the Royal Crown, a testimony to the loyalty of the quayside. The women then had a meal and returned the gallant Welshman. to the quay to meet them. As early tourists visited Wales the fame of the Conwy pearls proved a draw for ladies of fashion and in the Fishing 1800’s, a large sum of £80 was offered by a Duchess for Fishing for mussels from below the water was done a particularly fi ne pearl, with local fi shermen employed for four hours at low tide and the departure time from to fi sh for the valuable commodity. Conwy arranged so the boats sailed downstream on the ebb tide and after fi shing, back to the quay on the fl ood. Blue mussels Two men could be seen in each boat leaving Conwy for an area called the Deep with two mussel rakes, or crams, The other variety, Cragen Las was found in higher to fi sh for mussels in a process called codio’r dwfn concentrations on the bar at the mouth of the river. In (lifting from the deep). One rake had a 12-foot handle the mid 1830’s the blue mussel was gathered on the and another from 18 to 30 feet in length that ranged in ebb tide in abundance by men, women and children, diameter from 2 inches at the bottom to 1½ inches at the from beds with names such as Y Popty, Cae Conwy, top. The rakes were made of pitch pine, with 10-12 long Sgiaps, Y Morfa, Y Men, Westras and Cerrig Duon. The sharpened metal prongs of 8-10 inches length, fi tted mussels, placed in sacks and baskets, were transported with a net on the underside (see photograph overleaf). to Cefnro, at the northern extremity of the Morfa, or marsh and boiled in large iron pots called crochanau, or The rakes were thrown outwards from the boat as far as pits called ‘pearl kitchens’ each 5 feet square, 6 to 7 feet the men could reach and the poles rested on the shoulder high and constructed of wattle and gorse. The fi sh was and hand drawn along the seabed by the fi shermen picked out and stamped to a pulp with the feet in a large towards them with downward pressure applied on the tub and water added. The mussel fl esh, called solach handle at the same time to loosen the mussels. The poles fl oated and was used as a food for ducks. The sand, were drawn up, hand over hand and at the same time stones and the smallest pearls, which fell to the bottom, twisted so that the mussels transferred from the prongs were separated