Sampling aboard northern New Brunswick draggers from 1956 to 1961 shows a substantial reduction in the percentage by numbers and by weight of the catch of cod discarded at sea. The total numbers of cod discarded in the southwestern Gulf of St. Lawrence, which amounted to about 7 million in 1956, have been reduced to an estimated 1 million in 1961. Two factors are mainly responsible for this reduction: large-mesh nets which, following an ICNAF recommendation, became effective in 1957, and reduction in sizes retained for landing. The mesh effect is believed to be 1.3 times greater than the cull effect in reducing cod discards in 1961. Discards of American plaice have increased during the same period, due to larger recruitment of young year classes. Discards of species other than cod and plaice are negligible because they are only a small part of the catch. Survival experiments show that most cod and plaice are dead when returned to the sea. The use of large-mesh codends may result in long-term increase in the total cod landings in the southwestern Gulf of St. Lawrence.