Ecology of Freshwater Fish 2015: 24: 443–455
Ó 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
ECOLOGY OF FRESHWATER FISH
Movement and habitat use of the freshwater catfish (Tandanus tandanus) in a remnant floodplain wetland Wayne M. Koster1,2, David R. Dawson1, Pam Clunie1, Fern Hames1, John McKenzie1, Paul D. Moloney1, David A. Crook1,3 1
Department of Environment and Primary Industries, Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, Vic. 3084, Australia School of Life and Environmental Sciences, Deakin University, Warrnambool, Vic. 3280, Australia 3 Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia 2
Accepted for publication May 22, 2014
Abstract – Knowledge of the movement and habitat use of fishes is important in identifying and understanding the causes of population declines and predicting how populations are likely to respond to management interventions. In this study, radiotelemetry was used to examine the spring and summer movement and habitat use patterns of the freshwater catfish (Tandanus tandanus) in a remnant wetland to inform the development of recovery actions for this threatened species. Twenty-one adult fish were tagged and released within Tahbilk Lagoon, Victoria, Australia, in September 2009. Fish were located every 1–2 weeks between September 2009 and February 2010, a period which coincides with the spawning period for the species. Eleven of the fish were also tracked every 2 h for 68 consecutive hours in December 2009 to examine diel movements. The study revealed that freshwater catfish make extensive use of cover (e.g. wood and macrophytes) and typically have limited ranges (median total linear range and 90% linear range 599 and 173 m respectively), although they occasionally moved more extensively (up to 1.5 km) between floodplain and riverine habitats. Fish moved over much greater areas at night compared with during the day. There was also evidence of sex-specific variation in movement, with a trend for greater movement of female fish at night compared with males. The results of the study suggest that strategies that protect macrophyte and wood habitats and improve connectivity between riverine and floodplain habitats are likely to be important in maintaining and restoring remnant populations of this species. Key words: woody debris; macrophyte; telemetry; wetland; catfish
Introduction
Freshwater fishes throughout the world face many threats, including habitat degradation and loss, altered hydrology, barriers to movement, and introduction of alien species, and are among the most threatened fauna in the world (Cooke et al. 2012). In response, efforts to conserve and restore habitat for freshwater fish are underway in many countries. Examples include the addition of large woody debris to provide structural habitat (Nicol et al. 2004), restoration of riparian vegetation (Opperman & Merenlender 2004) and reconnection of main channel and floodplain
habitats to improve fish passage connectivity (Paillex et al. 2009). Detailed knowledge of movements and habitat use of fishes can play a key role in identifying and understanding the threats (e.g. habitat degradation, flow modification, barriers) that have led to population declines and provide an indication of how populations are likely to respond to management interventions such as habitat restoration (Rolls et al. 2013). Most studies of the movement of freshwater fishes have been undertaken in river and stream main channel habitats (Jungwirth et al. 1998), whereas movement and habitat use in off-channel habitats such as
Correspondence: W. M. Koster, Department of Environment and Primary Industries, Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, Vic. 3084, Australia. E-mail:
[email protected]
doi: 10.1111/eff.12159
443
Koster et al. floodplain wetlands have received much less attention (Hohausova et al. 2003; Lyon et al. 2010; Conallin et al. 2011). Wetlands provide important habitat, refuge and breeding opportunities for many fish species (Junk et al. 1989; King et al. 2003). Unfortunately, degradation of wetlands (e.g. through drainage and altered water regimes) has led to extensive reductions in the diversity and abundance of wetland fish assemblages (Jones & Stuart 2008; Beesley et al. 2012). There is, therefore, a pressing need for increased knowledge of the spatial ecology and habitat requirements of wetland fishes to help inform conservation and restoration efforts (Henning et al. 2007). Catfishes (order Siluriformes) are present in nearly all freshwater habitats around the world, including rivers, lakes and wetlands, and many are imperilled (Kwak et al. 2011). The freshwater or eel-tailed catfish (Tandanus tandanus; Mitchell, 1838; Family Plotosidae) is found only in the Murray–Darling Basin and coastal catchments of eastern Australia and inhabits wetlands, lakes and slow-flowing streams. Freshwater catfish have declined in distribution and abundance since at least the 1930s and are listed as threatened in Victoria and South Australia and as an endangered population in the Murray–Darling Basin in New South Wales. The causes of the decline of freshwater catfish are unclear but possibly include habitat loss (e.g. wetland draining), altered flow regimes, thermal (i.e. cold water) pollution and the impacts of alien fish species. The introduced common carp (Cyprinus carpio), in particular, is thought to have had a strong adverse impact on freshwater catfish, as both species are benthic feeders, prefer slowflowing habitat and have strong dietary overlap (Clunie & Koehn 2001). Previous studies have shown that freshwater catfish are generally sedentary and benthic in rivers (Davis 1977a,b; Reynolds 1983), but little detailed information is available on their movements and habitat use in wetlands, despite this being the species’ predominant habitat. The aim of this study was to use radiotelemetry to examine the day-to-day and spawning season movements and habitat use of freshwater catfish in a remnant wetland to inform the development of recovery actions. In particular, we tested the hypothesis that diel period and sex influence movement rate and habitat preference during the spawning period. Materials and methods Study area
The study was conducted in Tahbilk Lagoon in the Goulburn River basin, about 10 km south-west of Nagambie in central Victoria, Australia (Fig. 1). Tahbilk Lagoon supports the most southerly remnant 444
Fig. 1. Location of the study site. Dashed line denotes channels connecting Tahbilk Lagoon with the Goulburn River.
population of freshwater catfish in Victoria. The lagoon is one of the few strongholds for the species in Victoria, and protection of this population is a high priority (Clunie et al. 2008). Tahbilk Lagoon is about 5 km long and 50–80 m wide, with a surface area of 158 ha and a depth typically
