Hydroacoustic observations of surface shoaling behaviour of young-of-the-year perch Perca fluviatilis (Linnaeus, 1758) with a towed upward-facing transducer

Upward echosounding revealed the presence and near-surface distribution of pelagic juvenile perch and therefore this method can be used as a complementary survey tool to get more precise information about the distribution, behaviour and abundance of near-surface fish.