Hicks, B.J., Brijs, J. & Bell, D. (2009). Boat electrofishing survey of Lake Rotokaeo, Hamilton. CBER Contract Report No. 93, client report prepared for National Institute of Water and Atmosphere. Hamilton, New Zealand: Centre for Biodiversity and Ecology Research, Department of Biological Sciences, School of Science and Engineering, The University of Waikato.
Abstract
Lake Rotokaeo (Forest Lake) is a small (3.7 ha) lake set in suburban surroundings in the north-west of Hamilton city located at 37° 46.387’S and 175° 15.059’E. The lake is very shallow, with ~80% of its area <1.8 m water depth, depending on season. The bed is composed of soft sediments, and margins vary from grassed parkland to restored native wetlands and forest vegetation.
On 12 December 2008, we conducted eleven 10-min fishing shots comprising nine shoreline shots and two mid-lake shots. The shallowness of the lake precluded fishing along the western shored of the lake. All introduced fish species were removed and humanely killed, whilst all native fish species were counted, measured for length and returned to the lake. Water temperature recorded at the start of fishing was 21.3°C, and electrical conductivity was 110 µS cm⁻¹ ambient and 118 µS cm⁻¹ specific. The water had a distinct brownish hue, indicating tannin staining, but there was no obvious suspended sediment. The black disc measurement (horizontal water clarity) was 0.55 m. Aquatic plants present in the lake included filamentous algae, water lily (Nymphaea sp.), and parrot’s feather (Myriophyllum aquaticum). Carex species and raupo (Typha orientalis) comprised the riparian and marginal vegetation.
