Does electrofishing harm freshwater pearl mussels?

1. Two experiments were carried out in a Scottish river to test the effects of electrofishing on endangered freshwater pearl mussels (Margaritifera ma rgaritifera). 2. In the first experiment, two areas of mussel bed were marked out as trea tment and control sites and the former was electrofished using standard equ ipment. The mussels were examined 10 min, 24 h and 35 days after treatment and their shell valve closure responses, burrowing capabilities and gravidi ties were recorded as signs of normal 'functioning'. 3. In the second experiment, individual mussels were marked as treatments a nd controls and the former were electrofished. These mussels were examined as before. 4. No mortalities occurred and no significant differences in 'functioning' between treatments and controls were observed in either experiment. 5. Since no measurable treatment effect could be demonstrated, it appears t hat electrofishing did not adversely affect the short-term survival of M. m argaritifera. Copyright (C) 2001 John Wiley & Sons, Ltd.