Loch Ryan Native Oyster BedsOur Undervalued Resource?Tristan Hugh-JonesAugust 2011, ICSR, Stirling University
Loch Ryan, SW ScotlandThe rights to the Oysters weregiven to the Wallace Family byKing William III in 1701, and haveremained in the family ever since.Loch RyanStirlingWallace family asked us to jointhem in partnership to restore thebed in 1996
12 kmWhere are the oysters?
NStranraer to the South5m deep12 kmChannel dredged to 7m2-3m tidal rangeLittle tidal exchangeSlow growth, 11g / yrWater up to 18 o CMain area worked to East3 km
Roxann SurveySilty mudMuddy sandFine sand
Strategy for RestorationOnly take out >70g to build stock numbers.Take a minimum of oysters, consistent withkeeping a presence on the bed – e.g. a boat andthree men.Stock are as important for cultch purposes as forspawning.Put back smaller stock in small dense beds to– Aid future harvesting– Improve fertilisation ratesSeparate these areas to maximise use of thescarce food resource.
Vital Spark and Haematopus fishing1.9m single dredgeCatch sorted on table at sternHarvesting largest 5% crop, andrelaying 95%
History of catches130 tonnes1.4m oysters10/11season
Historical Stock levels1958 – 1967 Stock estimated by Scottish MarineBiological Association as increasing from 300,000 to400,0001976 DAFS survey yielded an average of 12.5 oysters /dredge. Total stock estimated at 1 million.1976 – 1986 average 42 tonnes harvested with 3 boats.1987 stock estimated at 2.5m Only harvesting 10 tonnesp.a.1996 – About 20 tonnes harvested / year, able to fish2000 / tow.2010/11 Harvested 40 tonnes (38,000 dozen)
Total Stock 60 million?
NOSAP – an “endangered” speciesNative Oyster Species Action Plan, both in England andScotland.Scotland’s commitment to the Convention on BiologicalDiversity, Rio de Janeiro Earth Summit 1992, and theUK’s Biodiversity Action Plan.SNH coordinates this plan and has said, “the value ofprotecting the native oyster should have nationalimportance with major significance”At present, no large scale restoration projects havestarted due to funding, and guidance / support forsmaller projects will be soon available.
Satellite trackingChart Plotter
Depuration and marketing8 Stainless TanksEach hold 600KgFlow of water is12.5m 3 / hrSALSA approval
Scottish CustomersMartin WishartAndrew FairlieGleneaglesRogano’sSelling priceup to oyster£1 orUS$1.60
London customersIncluding:HarrodsRitz HotelSavoy HotelMark HixBibendum
ThreatsStranraer• New Stena ferry terminal movingfurther north in the Loch willimprove the water quality, byreducing the silt load.• TBT has reduced to new lowlevels.• Disease: Bonamia and Martellia.Policy is not to bring any newstock into the Loch. Too risky.
Undervalued? £10m sewage scheme.The FSAS said “any managed risklevel must be determined to beentirely effective at all times”SEPA strongly supported, sayingmost plants have mishapsScottish Water decided to pump allwaste water to open sea.WICS had doubts the £10m schemewould improve water. Sanctioned£1m to investigate.StranraerSEPA disagreed stronglyScottish Government said they wouldsupport and back the expenditure.
Rossmore Oyster Ponds, Cork, Ireland
OYSTERECOVER€5m FP7 ProjectBonamia investigationsSarah Culloty UCC
Summer 2011Used ponds in JulyParents were from the 5 thgeneration of survivors, so spatare 6 th generation, 23 years ofselective breeding.Some parents were 10 yrs, 250g, andhad survived Bonamia, although stillwith a 20% infection.Ponds produce about 1m spat / yr
Conclusions:The Native Oyster inScotland is rare, but it hasbeen supported by SEPA andthe Scottish Government.The only way to restore otherbeds is to make it profitablefor the farmers to put in thework.Loch Ryan is unique, andhas been well supported, andwe look forward to supportingother farmers who are keento grow Ostrea edulis.Tristan Hugh-Joneswww.lochryanoysters.com
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