Abundance of three flatfish species (Pleuronectiformes, Paralichthyidae) off northern Argentina and Uruguay in relation to environmental factors

Four seasonal research cruises were carried out in the Argentinian-Uruguayan Common Fishing Zone to collect biological data on flatfish species and analyse their distribution and abundance patterns in relation to the environmental characteristics of the area. Physical data such as depth, temperature, salinity and sediment type were recorded at each trawling station. A canonical analysis was performed to analyse the correlation of flatfish abundance to these environmental factors. The results indicate that depth largely determines flatfish distribution in the study area. Paralichthys patagonicus and P isosceles were most abundant at 41 to 70 m depth, whereas Xystreurys rasile occurred mainly at 71 to 100 in. P patagonicus was more abundant in water of higher temperature and lower salinity, whereas P isosceles and X rasile occurred mostly at lower temperatures and higher salinity. There was no significant correlation of species distribution and abundance to sediment type when the latter was considered by itself, but they were significantly correlated to sediment type in association with either depth or latitude. At shallow depths the abundance of all three paralichthyid species was negatively correlated with sandy sediments.