The use of island water dynamics by spawning red cod, Salilota australis (Pisces: Moridae) on the Patagonian Shelf (Southwest Atlantic)

The red cod Salilota australis (Moridae) is an abundant fish that inhabits shelf and slope waters around the southern tip of South America. Despite its wide distribution in the Southwest Atlantic, red cod spawns predominantly in areas adjacent to two upwelling areas created by the cold-water Falkland Current in the west and southwest of the Falkland Islands. After their winter migrations from the Patagonian Shelf, red cod aggregate in dense spawning schools at depths between 180 and 200 m in the periphery of these upwellings in water densities of Sigma–t between 26.55 and 26.65 kg/m3. The timing (September–October) and extent of the spawning peak of red cod correspond well with the spring peak in primary production in the water. Red cod spawn near upwelling areas with western–northwestern direction of water flow that produce eddies with warmer sea surface temperatures (∼2 °C warmer) than the eastern eddies. Thus red cod make effective use of the Falkland Islands oceanography, spawning upstream in highly productive upwelling waters and then dispersing their pelagic larvae downstream in the warmer western branch of the Falkland Current over the Patagonian Shelf.