ABSTRACT Connectivity between rivers and floodplain wetland habitats has potential benefits for native fishes through enhanced movement opportunities for feeding, spawning, and recruitment. In regulated river systems, natural connecting flows may be substantially altered or lost, and in some cases, these connections are controlled by regulators between rivers and wetlands. In this study, we investigated whether using regulators to improve connectivity between rivers and floodplain wetlands is effective in facilitating the movement of adult fish into wetlands to spawn and the subsequent dispersal of juvenile fish to rivers. We used fyke netting and seining within wetlands (control and impact) to investigate changes in fish catch rates resulting from the provision of lateral connectivity and bi‐directional fyke netting in flood runners and creeks (connecting wetlands or wetland complexes with rivers) to investigate the directional movement of Australian Smelt ( Retropinna semoni ) and Carp Gudgeon ( Hypseleotris spp). The catch rates of adult Australian Smelt increased in wetlands connected to the river during late winter/early spring relative to those that remained disconnected. No difference in catch rates in wetlands was detected for adult Carp Gudgeon. In complex forest flood runners and creeks, adult Australian Smelt moved against the current when connectivity was supplied. No directional movement was detected toward or away from wetlands that were close to the river (i.e., with short connections of < 150 m) where water tended to flow into the wetlands. No directional movement was detected for adult Carp Gudgeon. Where connectivity was available, juveniles of both species dispersed toward the river in large numbers in spring following spawning and recruitment in wetlands. The current study demonstrates the benefits of managed connectivity between the Murray River and floodplain wetlands (i.e., an increase in the abundance of adult native fish in wetlands prior to their spawning season and large amounts of emigration of juvenile native fish to the Murray River following spawning and recruitment). These results should be used to create more specific objectives or targets for managed floodplain connectivity in the Murray River system and can be used to support management actions to increase the spatial extent of floodplain connectivity, not only in the current study area but globally.
Amtstaetter et al. (Thu,) studied this question.