In 1949, the eminent fisheries biologist Kenneth (‘Kay’) Radway Allen published a paper entitled: “The New Zealand grayling – a vanishing species”. What Radway Allen couldn’t have known was that the species was very likely already extinct at the time he wrote the paper. The last reliable sighting of New Zealand grayling Prototroctes oxyrhynchus was in the late 1930s, and they were officially listed on the IUCN Red List as “Extinct” in 1996.
The only other member of the genus Prototroctes is the Australian grayling P. maraena, which was once highly abundant in coastal south-eastern Australia, including Tasmania. However, by the 1970s it was clear that the species had declined significantly, and it was listed as Potentially Threatened under ASFB’s inaugural threatened fish list in 1987 and as Vulnerable in the Endangered Species Act 1992. A review of the species’ conservation status in 2021 estimated that the area of occupancy had declined by 62% since 1993. However, the conservation status was assessed as Vulnerable under IUCN criteria, and it remains in this category on the Federal EPBC Act.
The severe historical and contemporary declines in abundance and distribution indicate that P. maraena is on a continuing downward trajectory and faces a high risk of extinction within the next few decades. This presentation explores the reasons for the Vulnerable listing (as opposed to a higher threat category) and makes recommendations for future conservation status assessments of amphidromous species, like P. maraena, that exhibit dispersive metapopulation dynamics. We also outline key management actions required to stabilise the species’ metapopulation and support future recovery.
By recognising the urgency of the threats faced by P. maraena and allocating appropriate resources towards its conservation, there is no reason why this important component of Australia’s biodiversity should follow its cousin’s path to extinction.