Snow crab is traded in ounce grades — 3–5 oz, 5–8 oz, 8 oz+ — and those three labels do a lot of work in a market where they describe only one variable.
What a cluster is
A cluster, or section, is several legs still attached to a piece of the body shell. The crab is cut, cooked and frozen; the cluster is the tradeable unit.
What the grade measures
The ounce grade is the weight of one cluster. That is all it is.
It does not describe how much meat is inside the shell. It does not describe how many clusters are in the carton. It does not describe whether legs are intact. And unless the contract says otherwise, it does not even tell you whether the weight was measured before or after glazing — a distinction that moves a cluster between grades.
The five fields
1. Grade, with the measurement point. “5–8 oz, graded pre-glaze” is a specification. “5–8 oz” alone is half of one.
2. Minimum meat fill. Expressed as a percentage, with the assessment method stated. Fill follows the moult cycle; two clusters of identical weight can yield substantially different amounts of meat. See understanding crab meat fill.
3. Count per carton. Two cartons at the same grade and the same net weight can hold different numbers of clusters. If your operation plates by the cluster, count is what you are actually buying.
4. Glaze percentage and net-of-glaze weight. A 5–8 oz cluster at 12 % glaze and one at 20 % glaze are not the same purchase. Price against net of glaze.
5. Leg breakage tolerance. Stated as a percentage of clusters, assessed on arrival to an agreed method. Broken legs are not a defect in the crab; they are a handling outcome, and the tolerance is negotiable.
Dates
Ask for three: catch date, production date and pack date. They are usually close together but not always, and the gaps tell you about the route the product took.
Cooked, and how it was frozen
Snow crab is normally traded cooked. Whether it was brine frozen or air frozen, and whether the freezing happened at sea or ashore, affects appearance and drip. Declare it.
A complete line
Snow crab (Chionoecetes opilio), Barents Sea, cooked frozen clusters, 5–8 oz graded pre-glaze, minimum meat fill [x] %, glaze 12 % maximum, price per kg net of glaze, maximum [y] % clusters with broken legs, approx. 9–10 kg carton, count per carton to be stated, catch and pack dates per lot.