Vertical distribution and movements of brown bullhead (Ameiurus nebulosus Lesueur 1819) in Motuoapa Bay, southern Lake Taupo, New Zealand.

Reports that ultrasonic telemetry was used to determine the swimming depths of brown bullhead (Ameiurus nebulosus) in Motuoapa Bay at the southern end of Lake Taupo, New Zealand. Surgical implantation of sonic transmitters equipped with a pressure sensor in 12 adult fish; Recording by three automatic receivers of data points on swimming depth between November 26, 1998 and November 7, 1999; Evidence of seasonal variation in the depth of the water that the Brown bullheads swam in; Increased activity at night when they used shallow water extensively, especially during the winter months; Findings that they were most mobile in spring when they left Motuoapa Bay, suggesting migratory behavior; Findings that during winter the fish remained more stationary, only moving around inside the bay; Implications for the study results that provide guidance for establishing a brown bullhead control program should it become necessary.