AbstractThe salmon (salmo salar) is a large delicately flavoured fish found inseas and rivers on both sides of the Atlantic. Most of the commercial netting and certainly all the trapping and illegal poaching in Welsh rivers today is concerned with catchingsalmon and its close relation the migratory trout or sewin (salrno truttai). In some rivers, notably the Tywi, Dyfi and Conway, the netting of sewin is as important, if not more important, than fishing for salmon, and those three rivers are noted for large fish. The Tywi is a particularly important sewin river, the seine netsmen of the estuary landing 711 sewin as compared with 221 salmon in 1969. In the same year the coracle fishermen of Carm arthen caught 1,470 sewin compared with 257 salmon.