Immediate mortality of electroshocked fish was related to the stage of development after hatching. Larvae and juveniles of four species of fish were exposed to homogeneous voltage gradients (2-16 V/cm) of 60-Hz pulsed DC in water having an ambient conductivity of 100 muS/ cm. Recently hatched fish and fish older than 100 d did not die after electroshocking. The developmental period most susceptible to electroshocking-induced mortality was near the time of transformation from larvae to juveniles for all four species. The highest predicted mortality occurred 22 d after hatching or at 19-21 mm total length (TL) for bluegill Lepomis macrochirus, 36-41 d or 29-32 mm TL for largemouth bass Micropterus salmoides, 42-43 d or 27-30 mm TL for channel catfish Ictalurus punctatus, and 38 d or 21 mm TL for Nile tiapia Oreochromis niloticus. During a 5-d observation period, there was no delayed mortality of channel catfish. A field validation experiment with 25-d-old largemouth bass (14-22 min TL) indicated that mortality in the laboratory or around an electrofishing boat did not differ if voltage gradients were similar.
|Number of pages||8|
|Journal||Transactions of the American Fisheries Society|
|Publication status||Published - 2003|