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Pacific oyster:professional buying guide, sizes No. 0 to 5, fine or spéciale, growing areas

Pacific oyster for the trade: sizes No. 0 to 5, fine, spéciale, de claire, growing areas, triploid, health label, storage and pitfalls.

Updated 7 min readLiveCriée editorial team

Contents
  1. Buying sheet
  2. How to read an oyster offer?
  3. What pitfalls to avoid?
  4. What to replace a missing oyster with?
  5. What makes the price of oysters move?
  6. Frequently asked questions

The Pacific oyster, or cupped oyster (huître creuse; Magallana gigas, long named Crassostrea gigas), is the oyster farmed in the seven major French shellfish-farming areas, from Normandy to the Mediterranean; it is sold live, in boxes or baskets (bourriches), by size (No. 0 to No. 5, from largest to smallest) and by flesh quality ("fine" or "spéciale", possibly finished in a claire pond). France is the leading European producer. The flat oyster (Ostrea edulis) is a different species, with its own scale of sizes.

Buying sheet

Pacific oyster
Scientific nameMagallana gigas (synonym Crassostrea gigas)
SeasonAll year round. Sales concentrated at the end of the year. In summer, diploid oysters are "milky" (spawning); triploids, which produce very few gametes, are hardly milky
InterruptionsNo fishing, so no regulatory rest period, but health closures of production areas by prefectoral order; oysters under the Marennes Oléron PGI are only sold from 1 September to 31 May
Sizes (weight per oyster)No. 0: over 150 g; No. 1: 121 to 150 g; No. 2: 86 to 120 g; No. 3: 66 to 85 g; No. 4: 46 to 65 g; No. 5: 30 to 45 g
Flesh categoriesFine: fill index from 6.5 to 10.5 (excluded). Spéciale: 10.5 and over. Fine de claire, spéciale de claire: finished in a claire pond for at least two weeks (1 kg per m² at most) or three weeks (3 kg per m² at most)
Growing areasNormandy and North Sea, northern Brittany, southern Brittany, Centre-Ouest, Marennes-Oléron, Arcachon-Aquitaine, Mediterranean. Imports: Ireland, Portugal, Channel Islands and other European countries
Farming methodsIn bags on trestles (off-bottom), on the ground, in deep water, on ropes in the Mediterranean. Spat from natural collection (diploid) or from a hatchery (diploid or triploid)
Quality marksHuîtres Marennes Oléron PGI; Label Rouge fines de claires vertes, pousse en claire, oysters grown at sea; organic
FleshDrained flesh weighs 6.5 to 10.5% of the weight of a fine, 10.5% and over of a spéciale; about 10% on average according to the FAO
StorageBetween 5 and 15 °C, flat, without turning them over, away from light; 4 to 5 days (DGCCRF). No fresh water, no excessive cold

Sources: DGCCRF (sizes, categories, growing areas, storage), 2021 interprofessional agreement (finishing in claire ponds), Regulation (EC) No 853/2004 (health label); labels guide on this site.

How to read an oyster offer?

A price list or label line for oysters combines four pieces of information. The first two are measurable facts, the other two tell the origin:

ElementExampleWhat it says
SizeNo. 3The weight per oyster (66 to 85 g)
CategoryspécialeThe proportion of flesh (index of 10.5 and over)
Finishingde claireA stay in a finishing pond, with regulated duration and density
Origingrown in southern Brittany, finished in Marennes-OléronWhere the oyster grew, where it was finished

The size is chosen by use: No. 3 and No. 4 for eating raw, No. 3 being the most sought after according to the DGCCRF; No. 2 and larger for hot or gratinated oysters; No. 5 for assortments and entry prices.

What pitfalls to avoid?

  • The wrong size on the label. The DGCCRF regularly finds incorrect sizes, especially on No. 3, the most sought after. Weigh a dozen on receipt: a No. 3 weighs 66 to 85 g each.
  • Misleading prestige origin. "Marennes-Oléron" or "Arcachon" on an oyster merely shipped from Marennes or Arcachon is a deception reported by the DGCCRF, as is passing off as French oysters grown in Ireland, Portugal or Guernsey. Read the country of farming and the place of finishing.
  • Fine and spéciale confused. A spéciale contains more flesh than a fine of the same size, and costs more: check the category, not only the number.
  • The gaping oyster. An oyster that opens by itself is dead: it cannot be sold.
  • The health label. Every box or basket carries the health label, with the packing date, the name of the shipper, and the mention "these shellfish must be alive at the time of purchase" or a use-by date. The professional who splits the box keeps it for at least 60 days (see the traceability guide).
  • Diploid or triploid. This mention is not among the label mentions listed by the DGCCRF. If your customers refuse milky oysters in summer, ask for it; if they insist on oysters "born at sea", ask for that too.

What to replace a missing oyster with?

SituationSolution
Health closure of a growing areaSame size and same category from another area
No. 3 unavailable or too expensive at the holidaysNo. 4 spéciale (smaller, just as fleshy) or No. 2
Summer, customers who refuse milky oystersTriploid oysters, or oysters from colder areas
Premium offerFlat oyster, in a size from its own scale

What makes the price of oysters move?

Oysters do not go through the fish auction: there is therefore no average first-sale price comparable to that of fish. Three public benchmarks give an order of magnitude.

Public price benchmarksOyster
Sales by shellfish farmers, 202390,410 t for €515 million, i.e. about €5.70/kg on average
French exports, 2024volumes up 3%, average price down 9%
EU exports to non-EU countriesabout €8.30/kg in 2020, about €9.10/kg in 2024 (France: 69% of their value)

Sales by shellfish farmers: FranceAgriMer, Chiffres-clés 2024 (Agreste data, latest year published: 2023), average calculated by the editorial team, all oysters, all sizes and all customers combined. Exports: EUMOFA, Monthly Highlights No 8/2025. These averages are not a purchase price: size, category, finishing, shipping, transport and margin make up the price paid to the shipper.

The price of oysters is decided at the end of the year: according to the French National Shellfish Farming Committee (Comité national de la conchyliculture), cited by EUMOFA, about 70% of annual French consumption takes place during the holidays, mostly at Christmas. In December 2023 and again in December 2024, norovirus episodes led to temporary sales bans in several production areas, at the height of the season. In 2024, household purchases fell by 11% in volume (Kantar panel for FranceAgriMer) and prices went down, on the domestic market as well as for exports. No public source gives prices by size or by category: comparison is made on the shippers' offers, at equal size, category and finishing.

  • The holidays: the end of the year concentrates a large share of sales; it is also when the sizes in demand get tight.
  • Size and category: spéciale above fine, claire above unfinished oysters, Label Rouge and PGI higher still.
  • Winter health closures (norovirus), which take a growing area off the market from one day to the next.
  • The growing area and the reputation of the origin.

Frequently asked questions

What do oyster numbers mean?

The number gives the weight per oyster: the smaller the number, the larger the oyster. A No. 0 is over 150 g, a No. 3 weighs 66 to 85 g, a No. 5 30 to 45 g.

What is the difference between a fine oyster and a spéciale oyster?

The amount of flesh. A fine has a fill index of 6.5 to 10.5; a spéciale, 10.5 and over. At equal size, the spéciale is fleshier and more expensive.

What is a fine de claire?

A fine oyster finished in a claire, a shallow clay pond, for at least two to three weeks, at limited density. The spéciale de claire follows the same finishing rules with the flesh index of a spéciale. It is the speciality of Marennes-Oléron.

How to store oysters?

Between 5 and 15 °C, flat, without turning them over so they keep their water, away from light, for 4 to 5 days at most (DGCCRF). Never in fresh water.

What is the price of oysters?

There is no public quotation by size. Benchmark: in 2023, shellfish farmers sold 90,410 t of oysters for €515 million, i.e. about €5.70/kg on average, all sizes and all customers combined (FranceAgriMer, Agreste data). The professional purchase price depends on size, category (fine, spéciale), finishing and period, the end of the year concentrating most of the demand.

Sources

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