Mustelus schmitti (Carcharhiniformes: Triakidae) studied in the present work were caught incidentally in the shrimp fishery of the south of Bahía Engaño (Patagonia, Argentina). This bay is a shallow water, high productivity coastal area where shrimps and small fish are abundant throughout the warmer months. Young of M. schmitti are found in the bay from late spring to mid autumn. The analysis of stomach contents showed that the young feed mainly on crustaceans; the shrimp Artemesia longinaris being the main prey item. The bay serves as a nursery area for M. schmitti, and the length range and umbilical scars present in all the specimens studied revealed that the individuals were newborns.At Bahía Engaño, fishing trawls in the intertidal and surf zone are common, and ∼80% of the total number of species caught is considered as by-catch. The newborns and juvenile M. schmitti are an important element of this by-catch. Since the reproductive potential of the smoothhound shark is low, the protection of these newborns and juveniles from fishing pressure is of great importance.