Efficiency of electrofishing in turbid lowland rivers: implications for measuring temporal change in fish populations

摘要: To quantify how electrofishing capture probability varies over time and across physiochemical disturbance gradients in a turbid lowland river, we tagged between 68 95 fish·year−1 with radio transmitters up to 424 external passive integrated transponder (PIT) tags. We surveyed the site noninvasively using radiotelemetry determine which of radio-tagged fish were present (effectively closing population emigration) then electrofished estimate proportion available that captured based on both this standard mark-recapture methods. replicated surveys three times minimum 12 days each year, for 7 years. Electrofishing varied 0.020 0.310 years four different large-bodied species (Murray cod (Maccullochella peelii), trout macquariensis), golden perch (Macquaria ambigua ambigua), silver (Bidyanus bidyanus)). River turbidity associated increased river discharge negatively influenced probability. Increasing length detection 500 mm Murray cod, after decreased. Variation large rivers results additional uncertainty when estimating size or relative abundance. Research monitoring programs as an indicator should incorporate strategies lessen potential error might result from changes probabilities.