When buying fish, many people check the price, expiration date, and species, but there’s another detail on the label that can tell you something important: the FAO fishing zone. This number identifies the broad geographical area where the fish was caught, helping consumers understand where products such as tuna, salmon, cod, trout, and swordfish come from. It can also apply to molluscs and crustaceans.

The system divides the world’s oceans and seas into numbered regions. For example, FAO 37 means the Mediterranean and Black Sea, while 27 covers the Northeast Atlantic and Baltic Sea. Other major zones include 21 for the Northwest Atlantic, 31 for the Central-West Atlantic, 34 for the Central-Eastern Atlantic, 41 for the Southwest Atlantic, 47 for the Southeast Atlantic, and several numbered regions covering the Indian and Pacific Oceans. 🌍

The number can be especially useful when you’re buying packaged, frozen, or preserved seafood, where you can’t simply ask a fishmonger where it was caught. More specific subareas can provide additional geographic detail. However, an FAO number is not a simple “good” or “bad” rating. It tells you location, not automatically the quality, freshness, or safety of the fish.

One zone that has received particular attention is FAO 61, covering a large part of the Northwest Pacific, including waters near Japan. Following the 2011 Fukushima nuclear disaster, concerns about radioactive contamination led some countries to introduce restrictions or advisories involving seafood from affected areas. That history is one reason checking the fishing zone can be useful — the label gives you information that can help you make a more informed choice. 🐟🔎