M. Allen

Discovery of a pupping site and nursery for critically endangered green sawfish Pristis zijsron

A pilot study targeting sawfishes in the southern Pilbara region of Western Australia, which is undergoing a major expansion in human activity, was conducted using gillnets during April and October 2011 in the Ashburton Estuary and adjacent mangrove creeks. Catch per unit effort was greatest in the Ashburton Estuary in October, due to an influx of green sawfish Pristis zijsron pups, and was orders of magnitude higher than previously reported for any Pristidae; the study sites contained P. zijsron up to almost 3 m total length. This study identified the first pupping site for P. zijsron in Western Australia, and the most southerly known nursery area for the species in Australian waters, and is potentially the most important globally.

Resolving the taxonomy, range and ecology of biogeographically isolated and critically endangered populations of an Australian freshwater galaxiid, Galaxias truttaceus

The spotted galaxias (or trout minnow), Galaxias truttaceus, is a species that is restricted to south-western and south-eastern Australia, but there has long been conjecture as to whether the geographically and Critically Endangered Western Australian populations represent a subspecies (Galaxias truttaceus hesperius). We provide evidence that Western Australian populations, on the basis of a combination of genetic, geographic and ecological criteria, should be considered an evolutionary significant unit, which merits management as a high conservation priority. Substructure at nuclear and matrilineal genetic markers is not suggestive of species-level divergence, but rather of discrete western and eastern Australian subpopulations with limited contemporary gene flow. In contrast to many eastern populations that are diadromous, all western populations are potamodromous. Adults live and spawn in riverine habitats and larvae drift downstream to coastal lakes, where they spend several months, before undertaking a distinct upstream recruitment migration as juveniles to colonise riverine habitats. Instream barriers that disconnect riverine and lentic habitats restrict distributional range and presumably affect reproductive success of Western Australian populations. Conserving the remaining populations in Western Australia will require ongoing efforts to reduce the impact of emerging threats, particularly those related to instream barriers, introduced species and reductions in water quantity and quality.