Advances in Active Netting Techniques, What Must be Standardized, and Where Is Flexibility Allowed

Active sampling methods can provide precise qualitative and quantitative assessment of fish community as they combine several advantages such as fast sampling in real time, well-defined sampling area and applicability to various lake types and habitats. However, fish behavior still plays an important role as fish may avoid the gear or the boat, and may escape the gear after encounter. Limits of a gear must be known to get a reliable picture of fish community and gear standardization should be implemented to achieve comparable data among different working teams.

Trawl and purse seine net for pelagic sampling and beach seine net for shallow inshore sampling are the most commonly employed active gears in freshwater environments. Recently, demand for “true picture” of fish community has brought numerous studies dealing with the application of these sampling methods. We present a general overview of gear typology and application and demonstrate several case studies from Europe and the United States to show the main gear limitations in term of design, sampling procedure or effect of the environment. The approaches for limit detections and consequences for standardization process will be then discussed. Further, potential direction for future research in the field will be highlighted.