Estuary perch (Percalates colonorum) is a long-lived, slow-growing native species that is distributed throughout estuarine-riverine systems in southeast Australia. In Tasmania, only one known population remains located in the Arthur River, on the northwest coast. As a result, Tasmania is the only Australian state to list estuary perch as protected (recreational and commercial). This is the most southern population of this species, and due to its highly restricted distribution and conservation significance, it has been the focus of ongoing monitoring and research.
Since 2014, five surveys of the population have been undertaken to assess the status of the population, enhance understanding of its biology, and inform management decisions. These surveys were undertaken in 2014 (n= 32, 0 tagged), 2014/15 (n= 189, 85 tagged), 2023 (n= 378 fish, 191 tagged), 2025 (n= 172 fish, 138 tagged) and 2026 (n= 13 fish, 11 tagged, however this was a filming event). A population estimate undertaken during the 2014/15 survey indicated that the population was small (825–2375 fish) and dominated by three old age classes. This population also has extremely low genetic diversity and is genetically distinct to mainland populations.
The most recent dedicated survey of the population in November 2025 aimed to re-assess its size structure and estimate abundance through tag-recapture methods. Age analysis of nine juvenile fish identified two cohorts (spawning events in 2022 and 2018), where the detection of the 2022 cohort provides encouraging evidence of recent successful recruitment.
Collectively, these surveys demonstrate that Tasmania's last remaining estuary perch population remains reproductively active despite its small size, restricted distribution and variable recruitment. The findings of this research highlight the importance of long-term monitoring, and will inform future conservation actions, that may include captive breeding, stock enhancement and the re-establishment of other populations of this species in Tasmania.