Evaluating migratory fish behaviour and fishway performance: testing a combined assessment methodology.
Baumgartner LJ, Boys CA, Stuart IG and Zampatti BP (2010) Evaluating migratory fish behaviour and fishway performance: testing a combined assessment methodology. Australian Journal of Zoology, 58: 154–164.
Many species of freshwater fish are migratory and require access to different habitats during their lifetime. Fishways, channels around of through a weir, are commonly used to help reinstate migration at sites where fish passage has been blocked. To provide passage for migratory native fish, a series of 15 new fishways are being constructed on the Murray River in south-eastern Australia. Three of these new fishways, on the mid-Murray River have been designed to provide passage for a broad size range of fish (30 – 1000 mm long). An assessment of these fishways was performed using a combined trapping and passive integrated transponder (microchip) approach. This combined assessment sought to determine how effectively these fishways at passing both large and small fish. Fish were trapped within the three fishways between 2004 and 2006 where a total of 13,326 individuals comprising 13 species were collected from 48 sample days (24 h each). Trapping data revealed that the three fishways successfully passed fish within the target size range, though significantly higher numbers of individuals smaller (10 – 29 mm long) than the target size range could not ascend. Microchipping revealed important information on fishway ascent times, descent times, seasonality and diel behaviour. Although both methods had advantages and disadvantages, the dual assessment approach was useful as it permitted an assessment of fishway success and also provided new information on migratory fish behaviour.