1. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Species considered Species considered Mussel Mussel oBlue mussel, Mytilus edulis oMediterranean mussel, M. galloprovincialis Oyster Oyster oFlat oyster, Ostrea edulis oPacific oyster, Crassostrea gigas oPortuguese oyster, Crassostrea angulata Scallop Scallop oCoquille St Jacques, King scallop, Pecten maximus oMediterranean scallop, Pecten jacobaeus Lobster Lobster oEuropean lobster, Homarus gammarus Others not considered Others not considered oClams  Manila clam, Ruditapes philippinarum  Carpet clam, Ruditapes decussata oCockles, Cerastoderma edule oRazor shells, Ensis spp.

2. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Mussels Mussels Three species of mussel distributed around Europe Three species of mussel distributed around Europe –Blue mussel, Mytilus edulis –Mediterranean mussel, M. galloprovincialis –Baltic mussel, M. trossulus Baltic mussel has no significant commercial value Baltic mussel has no significant commercial value Mediterranean mussel has expanded its range out of Mediterranean and hybridises with blue mussel Mediterranean mussel has expanded its range out of Mediterranean and hybridises with blue mussel Hybrid zone extends from Atlantic France to northern Scotland Hybrid zone extends from Atlantic France to northern Scotland Mosaic of pure species, and hybrids Mosaic of pure species, and hybrids Needs identifying, mapping and monitoring to identify species (or hybrids) being cultivated Needs identifying, mapping and monitoring to identify species (or hybrids) being cultivated Ground laying aquaculture of mussels involves movement of seed between areas and this can be having a genetic impact Ground laying aquaculture of mussels involves movement of seed between areas and this can be having a genetic impact No significant hatchery culture at present although R&D is being carried out No significant hatchery culture at present although R&D is being carried out Distribution of three mussel species in Europe

3. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Oysters Oysters Flat or native oyster, Ostrea edulis Flat or native oyster, Ostrea edulis Traditional oyster cultured from Roman times Traditional oyster cultured from Roman times Massive decline in production since its heyday in the 1800s Massive decline in production since its heyday in the 1800s Overfishing, pollution and diseases (Bonamiosis) Overfishing, pollution and diseases (Bonamiosis) Selective breeding for disease resistance carried out at IFREMER Selective breeding for disease resistance carried out at IFREMER New genetic map has allowed the search for Quantitative Trait Loci (QTLs) to begin New genetic map has allowed the search for Quantitative Trait Loci (QTLs) to begin

4. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe O. edulis is widespread across Europe O. edulis is widespread across Europe Patchy distribution Patchy distribution Main genetic impact is reduction in genetic variability from hatchery activities Main genetic impact is reduction in genetic variability from hatchery activities One microsatellite study showed significant loss of alleles from hatchery operations One microsatellite study showed significant loss of alleles from hatchery operations No loss of heterozygosity No loss of heterozygositypopulations No. of alleles locus -1 Heterozy- gosity wild17.60.829 hatchery9.20.839

5. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Oysters Oysters Pacific cupped oyster Crassostrea gigas Pacific cupped oyster Crassostrea gigas Non-native Non-native Highly productive and the most important oyster species world-wide Highly productive and the most important oyster species world-wide Has naturalised in many regions, for example the Atlantic coast of France Has naturalised in many regions, for example the Atlantic coast of France In some areas it is a pest species, for example in The Netherlands where it has recently invaded. In some areas it is a pest species, for example in The Netherlands where it has recently invaded. It is now invading southern Britain It is now invading southern Britain It competes for settlement space with native species such as mussels, barnacles and flat oysters creating a significant ecological impact on sheltered rocky shores It competes for settlement space with native species such as mussels, barnacles and flat oysters creating a significant ecological impact on sheltered rocky shores Aquaculture vs the environment Aquaculture vs the environment The classic way to eat oysters: half a dozen with a nice white wine!

6. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Seed for the industry is either produced in hatcheries Seed for the industry is either produced in hatcheries Or farmers collect natural spatfall Or farmers collect natural spatfall Seed oysters are deployed in bags on trestles at low water Seed oysters are deployed in bags on trestles at low water Most extensive areas of culture are in the Marrennes-Oleron region of France Most extensive areas of culture are in the Marrennes-Oleron region of France Hybridises with the Portuguese oyster (Crassostrea angulata) where the two species overlap between France and Portugal Hybridises with the Portuguese oyster (Crassostrea angulata) where the two species overlap between France and Portugal Significant genetic impact if hybridisation is extensive Significant genetic impact if hybridisation is extensive Risk of loss of genetic resource represented by Portuguese oyster Risk of loss of genetic resource represented by Portuguese oyster However, Portuguese oyster is non- native However, Portuguese oyster is non- native Was introduced hundreds of years ago. Was introduced hundreds of years ago.

7. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Oysters: genetic impact of the use of triploids Oysters: genetic impact of the use of triploids An increasing proportion of the oysters on the European market are triploids An increasing proportion of the oysters on the European market are triploids They are mainly sterile They are mainly sterile Insignificant quantity of reproduction Insignificant quantity of reproduction Any eggs, sperm or embryos are mostly non-viable Any eggs, sperm or embryos are mostly non-viable No genetic impact on naturalised populations No genetic impact on naturalised populations Valuable method to ameliorate invasion due to aquaculture Valuable method to ameliorate invasion due to aquaculture Tetraploid male x Triploid oysters Diploid female Tetraploid broodstock are difficult to produce and must be prevented from escape Requires the active involvement of Government Agencies

8. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Scallops Scallops Cocquille St Jacques, King scallop, Pecten maximus Cocquille St Jacques, King scallop, Pecten maximus Mediterranean scallop, P. jacobaeus Mediterranean scallop, P. jacobaeus Both species are cultured – usually on longline systems Both species are cultured – usually on longline systems Natural spat collected – very little hatchery produced seed Natural spat collected – very little hatchery produced seed There has been extensive re-stocking from hatchery seed in the Rade de Brest, France, over many years There has been extensive re-stocking from hatchery seed in the Rade de Brest, France, over many years Local stock used as broodstock – good management strategy Local stock used as broodstock – good management strategy However, risk of genetic impact through reduced genetic variation in hatchery product However, risk of genetic impact through reduced genetic variation in hatchery product More information needed on the population substructure of P. maximus and P. jacobaeus More information needed on the population substructure of P. maximus and P. jacobaeus

9. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Lobster (Homarus gammarus) Lobster (Homarus gammarus) One of most valuable shellfish by weight in Europe (14k Euros t -1 ) One of most valuable shellfish by weight in Europe (14k Euros t -1 ) Solitary, highly active, primarily nocturnal predators – unlike bivalves Solitary, highly active, primarily nocturnal predators – unlike bivalves Distributed throughout Europe Distributed throughout Europe Four main genetically identifiable groups: Four main genetically identifiable groups: –1. northern Norway, –2. the Netherlands, –3. the Aegean –4. Atlantic and outer Mediterranean coasts. There will be genetic impact due to commercial movements of lobsters between these areas There will be genetic impact due to commercial movements of lobsters between these areas Aquaculture production, although limited, is growing Aquaculture production, although limited, is growing

10. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Lobster aquaculture Lobster aquaculture Very difficult because of cannibalism of juveniles Very difficult because of cannibalism of juveniles Has been used extensively for re-stocking trials Has been used extensively for re-stocking trials Source of the berried females not considered Source of the berried females not considered Only a few females used leading to loss of genetic variability in re-stocked juveniles Only a few females used leading to loss of genetic variability in re-stocked juveniles One Norwegian hatchery producing market size lobsters in captivity One Norwegian hatchery producing market size lobsters in captivity Larvae from cultured lobsters are less fit that those from wild-caught lobsters Larvae from cultured lobsters are less fit that those from wild-caught lobsters This is an important potential genetic impact on wild populations if cultured lobsters are released This is an important potential genetic impact on wild populations if cultured lobsters are released

11. GENIMPACT Genetic impact of the aquaculture of shellfish in Europe Key considerations Key considerations We need to understand more about the complex pattern of hybrids and pure species of mussels in order to reduce potential genetic impact We need to understand more about the complex pattern of hybrids and pure species of mussels in order to reduce potential genetic impact Hatchery culture of flat oysters significantly reduces genetic variation Hatchery culture of flat oysters significantly reduces genetic variation Useful selective breeding for disease resistance Useful selective breeding for disease resistance Pacific oyster is invasive so has ecological impact Pacific oyster is invasive so has ecological impact Also has genetic impact by hybridizing with the Portuguese oyster Also has genetic impact by hybridizing with the Portuguese oyster Triploids could help to ameliorate effect of aquaculture on the spread of the species Triploids could help to ameliorate effect of aquaculture on the spread of the species Little genetic impact in scallops except possibly through re-stocking in Rade de Brest Little genetic impact in scallops except possibly through re-stocking in Rade de Brest Genetic impact on lobsters via movements of adults and through restocking efforts Genetic impact on lobsters via movements of adults and through restocking efforts Different species create different problems and require different solutions Different species create different problems and require different solutions