Comparison of Size Distribution of Fish Obtained from Gill Netting and the Distributions of Echoes from Hydroacoustics in Lake Dejguny (Poland)

A procedure is proposed to assess the impact of various relationships found in literature and used convert acoustic target strengths (TS) fishes’ total length (TL) with respect compatibility fish data obtained from vertical hydroacoustics gillnets. The study one set collected a 120 kHz echosounder across mesotrophic, dimictic Lake Dejguny. Four general multi-species TS–TL were tested for maximum dorsoventral characteristic: (1) relationship developed using mainly West Atlantic marine brackish water frequencies, (2) Salmonidae, Percidae, Cyprinidae families at kHz, as well shown by two generalized equations representatives (3) family (200 kHz) (4) Percidae kHz). In addition, other (5) perch (Perca fluviatilis) (6) roach (Rutilus rutilus). selecting most appropriate ratio began determining TS threshold that would eliminate small ineffectively caught Depending on relation, ranged ?48.5 dB ?45.5 dB, corresponding TL was range 62.3–93.0 mm. Then, linear regression, between percentage organized classes (TL), whose boundaries determined relationships, share recorded acoustically (with 1.5 interval) examined. fit regression model (percentage) assessed coefficient determination r2, mean absolute error (MAE), Nash–Sutcliffe efficiency (NSE), root square (RMSE). For Dejguny, similar distribution echo proportions larger than 62 mm relation (2), 74 mm, Pericidae (4). No evidence unambiguously verify meanings different sound frequencies (120 200 which analysis derived. can be select optimal equation.