Freshwater Fish Sampling in South America: Common Methods and Challenges for Standardization

Freshwater fish sampling in South American inland waters is quite a hard task due to the diversity of environments among basins and the diversity of species, body size, shapes and behaviors. The great beta diversity within the continent increases the challenges to develop standardized fish sampling methods, including minimal effort, particularly when assessment are needed in transboundary basins. Several techniques have been applied and adapted to sample for fish among this variety of conditions and to increase sampling efficiency. For technical/scientific studies the most common gears used in reservoirs, floodplain lakes and large rivers are floating and bottom gills nets, cast nets, hook lines and beach seines. At low order rivers and marshes, hand nets, small seines and electrofishing are most common techniques. Gill net is considered the gear with the most standardized application as Capture per Unit Effort (CPUE) can be easily estimated. However, there are several knowledge gaps that still need to be fulfilled in order to evaluate the possibility of standardizing fish sampling methods in South American freshwater bodies, based on gear settings, minimal effort needed (sampling sites and periodicity), materials, fish vulnerability and environmental variability. So far little effort had been made to develop this concept.