Restoration of oyster production in France by introduction of non-native species : history and overview J.Barret, A.Gerard, P.Goulletquer, JP Baud acknowledged for documents HEGARET Hélène UCONN, Department of Marine Sciences, 1080 Shennecossett Road, GROTON, CT 06340, US MAZURIE Joseph IFREMER, Station de La Trinité Sur Mer, 12 rue des Résistants, BP 86, La Trinité Sur Mer, France

Historic (1) – Beginning of oyster farming European flat oyster, Ostrea edulis, harvested for several centuries. First Ostrea edulis farming in France Introduction of the Portuguese cupped oyster, Crassostrea angulata, into the Gironde estuary C. angulata and O. edulis on the French coast

Historic (2) – Introduction of Crassostrea gigas 1966 and 1969: First “Non-official” introduction of the Pacific oyster from Japan, into the Marennes-Oleron and Arcachon basins ; => excellent survival & growth performance : official, controlled introduction of 500mt of broodstock oysters from Canada and >5 billion spat from Japan, to Arcachon and Marennes.

Historic (3) – Virus and parasites Bonamia ostreae Source : Ifremer/drv/lgp Marteilia refringens spp. Source : Ifremer/drv/lgp C.gigas : first introduction C. angulata : Viral infection (iridovirus) => total loss C.gigas substitution and development 1966, 69- Cupped oysterFlat oyster Protozoan parasite, Marteilia refringens : production of O. edulis : (20,000 to 10,000t) Protozoan parasite, Bonamia ostreae : production 2,000t per year (10 M€).

t t t O. edulis C. gigas C. angulata Iridovirus Bonamia Marteilia French oyster production in the last century Graphiques: J.Barret

O. edulis farming today Attemps to eradicate M. refringens: unsuccessful ! No more farming in closed Bays and Estuaries (more sensitive to Marteilia development) New development in open Bays (Cancale, Quiberon) : low densities of seed (1 million per ha) no manipulations between seeding and harvest Resistant strain to B. ostreae developed and tested experimentally (validation trial in the field now). Photo Dao

Marteilia refringens Bonamia ostreæ Bretagne 20% Languedoc Roussillon t 10 M€ Only in deep waters since 1970 because of the 2 epizootics O. edulis farming today 80% Graphiques: J.Barret

The success of C. gigas (replacement of C.angulata …and more) Since 1975, natural reproduction & spat collection => No need for further importations Resists endemic parasites in French growing areas => replaces its “relative” C.angulata Expansion northward (supplants the declining O.edulis in Brittany) Successful

ARCACHON BANGOR VENISE OUALIDIA BREST SEUDRE COREE TAHADDAR T SETUBAL FARO CADIX TAIWAN Genetics of C. gigas and C. angulata Introduction from Japan since the beginning of the 70s (C. gigas) Introduction from Asia in the 15th centuary with portuguese fishermen (C. angulata) Source Ifremer : Boudry el al.

t 220 M€ C.gigas : diverse sites and a variety of culture techniques Principally on the Atlantic coast, in open, intertidal parcs On the Mediterranean coast, in natural semi- closed lagoons (subtidal) Graphiques: J.Barret

On the Atlantic side : Coasts with tides

On the bottom

Traditionnally (before 1970) Culture on the bottom after seeding

On « tables »

Since 1970 On « tables » in bags («poches ») elevated cm above surface 1 to 3 years of growth

In deep waters

Coasts without tides : Mediterranean coast (Thau lagoon mainly)

In suspension under racks (« tables »)

Bay of Mont-St-Michel : First Breton shellfish culture site Moderate local productivity, but high exchanges (15 m tides...) Low runoff influence Diversity of bivalves both natural (clams, cockles…) and cultivated (flat and cupped oysters, mussels…) Competition with a filter-feeding invader (150,000 mt of Crepidula)

Rade de Brest : urbanised... low production of mussels and oysters, but first success in Pecten maximus aquaculture

Quiberon Bay (South Brittany) Deep water bottom oyster farming (15,000 mt). Seeded from oyster dredgers, harvested with dredges.

Morbihan Golfe (Brittany) confrontation between shellfish culture and other activities

Marennes-Oléron Basin : Limits to development of oyster farming? Trophic Capacity limits (sustitution sites) Restriction through recent management plans (SMVM, Natura 2000), water quality standards

S. Costatum Haslea Ostrearia Diatoms responsibles for the greening of the gills Technique leading to official quality labels « fines et spéciales de claire » Finishing - « affinage » Few weeks to a few months of « affinage » in claires.

Long tradition of oyster farming Pollution problems (TBT…) Competition with high tourist pressure Arcachon Basin

THAU lagune : a shellfish culture « pond » Exceptionnally productive (commercial size within 1 year) fragile (eutrophication, contamination…) But highly protected (prevention of sewage from the drainage basin) Source : Chaussade et Corlay

There is no such thing as an unqualified success!

Associated flora and fauna (nuisances or not) Balanus amphitrite and B. albicostatus (cirripeds) Hydroides enzoensi (annelid) Aiptasia pulchella (cnidarian) Anomia chinensis (mollusc) Undaria pinnatifida (alga) Laminaria japonica (alga) …

Regulations / Recommandations for planned introductions ICES code of practice (Copenhagen 1994) Federation of European Producers (FEAP) code of conduct Assure a high standard of quality food production while respecting environmental considerations and consumer demands

NS Recent summer mortalities Essentially during the first summer Can reach up to 50% Management options: Changes in culture practices Selection of resistant strains Development of sterile (and fast growing) triploid oysters Ifremer REGEMO

The French experience summarized A risky success story C. gigas introduced where cupped (portugese) oyster farming existed : Arcachon and Marennes Northern expansion following collapse of flat oyster (Brittany): amenable to aquaculture, and high demand! However, C. gigas remains an introduced species => eventual mis-adaptations (mortalities) => a few undesirable by-species All the “oysters” in one basket !

Thanks Elaine Knight Rick DeVoe Dorothy Leonard And the all organization committee of the International Conference on Shellfish Restoration