Hicks, B.J. & Ring, C.A.(2004). Boat electrofishing survey of Te Weta Bay, Lake Rotoiti. CBER Contract Report No. 32, client report prepared for the Department of Conservation, Bay of Plenty Conservancy. Hamilton, New Zealand: Centre for Biodiversity and Ecology Research, Department of Biological Sciences, The University of Waikato.
Abstract
We used New Zealand’s first successful electrofishing boat to survey fish in Lake Rotoiti, North Island, New Zealand, principally in Te Weta Bay. The primary objective of the fishing was to see if undesirable fish species such as koi carp (Cyprinus carpio haemaotopterus; Zhou et al. 2003), brown bullhead catfish (Ameiurus nebulosus), and rudd (Scardinius erythophthalmus) have become established. Circular excavations were seen in the lake by a NIWA SCUBA diver in late 2003, and these were similar to nest excavations associated with catfish in other locations.
The native fish common smelt (Retropinna retropinna) and bullies (Gobiomorphus sp) were caught, with a few goldfish(Carassius auratus). Poor water visibility made observations difficult in some parts of the lake, especially on the southern shore and in the outer part of Te Weta Bay closest to the main lake.
Fish densities ranged from 2.3 to 11.7 fish 100 m⁻². These should be regarded as minimal densities because the electroshoked fish were counter from the boat but mostly not retrieved; also, only a single pass was conducted.
No recognised pest fish species were caught, but we cannot exclude the possibility that pest fish might occur at sites that were not fished. No trout were caught, possible because of the high water temperature (22°C).
