In riverine ecosystems, movements of biota among different parts of the river network are fundamental to the functioning and sustainability of populations, especially for fish. Globally, human activities (e.g., dam construction and altered flow regimes) have impaired riverine fish movements through reduced river connectivity, leading to well‐documented population declines. This study examined the timing and extent of movement of a nationally threatened potamodromous fish, silver perch (Bidyanus bidyanus), among different parts of the mid‐Murray River network in south‐eastern Australia using acoustic telemetry to identify the relative importance of different environmental variables (including river discharge) influencing timing and extent of movements. A total of 203 silver perch (fork length range 120–415 mm) was tagged in the Murray River. Silver perch occupied extended reaches of river (hundreds of kilometres) and multiple habitats throughout the river network, ranging from a large mainstem river to inflowing tributaries, anabranches and floodplain habitats. Movements were associated with aspects of the flow regime, such as small to moderate mainstem discharge rises and elevated tributary discharge. These results emphasise the importance of managing silver perch populations within an integrated riverscape context rather than solely focusing on reach/river scales. The inter‐relationship between silver perch movement and river discharge highlights the susceptibility of the species to river regulation, which has previously been implicated in its decline. The information on migratory behaviours in this study provides empirical evidence to support refinement and implementation of targeted restoration strategies, such as environmental flows, to assist the management and conservation of an imperilled species.

中文翻译：

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环境对低地河网中受威胁的河豚的迁移方式和途径的影响

在河流生态系统中，生物群在河网不同部分之间的移动对于种群（尤其是鱼类）的功能和可持续性至关重要。在全球范围内，人类活动（例如，水坝建设和水流状况的变化）通过减少河流的连通性而削弱了沿河鱼类的活动，导致有据可查的人口减少。这项研究检查了受国家威胁的河鳄鱼类银鲈（Bidyanus bidyanus），使用声波遥测技术在澳大利亚东南部的墨累河中游网络的不同部分之间，确定影响运动时间和范围的不同环境变量（包括河流流量）的相对重要性。默里河上总共标记了203条银鲈（叉长在120-415毫米之间）。银鲈占据了河流的延伸部分（数百公里）以及整个河网中的多个生境，范围从大型干河流到流入的支流，分水岭和洪泛区生境。运动与流动状态有关，例如小到中度的主干流量上升和支流流量升高。这些结果强调了在综合河景环境中管理银鲈种群的重要性，而不是仅仅关注河床/河流规模。银鲈运动与河水排放之间的相互关系突显了该物种对河水调节的敏感性，这以前曾与它的衰落有关。本研究中有关迁徙行为的信息提供了经验证据，以支持完善和实施有针对性的恢复策略（例如环境流量），以帮助管理和保护濒危物种。