This paper provides regression formulae for size estimation of kingsoldier bream (Argyrops spinifer) from measurements taken on bones enabling the reconstruction of the size of fish present in archaeological samples. Bones of Sparidae are commonly recovered from archaeological sites bordering the Arabian Gulf, and, of the species within this family, kingsoldier bream are relatively abundant with the bones also easily identifiable. The marine environment where this fish occurs varies throughout its life cycle, and therefore the reconstructed size of the fish can be used to infer the types of location where past fishing activities took place. Comparison of the estimated size of fish caught from two Late Islamic sites on the northwest coast of Qatar, in combination with other evidence, has been used to indicate differing frequencies of fishing methods at the two sites. This variation in fishing is caused by the topography of the coast in the immediate vicinity of the sites with shallow waters providing a wide tidal zone at the northern of the two with an environment suitable for fishing with stone‐built intertidal fish traps (known in Arabic as al maskar). The topography of the coast at the southern of the two sites is steeper, and the settlement was an important trading port so the coast was utilised primarily as a harbour rather than a fishing ground. The supply of fish at this settlement was provided by fishermen more commonly using basket traps (gargoor) and handlines with fishing taking place from boats. Copyright © 2015 John Wiley & Sons, Ltd.