Unlike their US and European counterparts, conservation of freshwater mussels in Australia is frequently met with disinterest or disregard. Despite their importance as ecosystem engineers, their applications as bioremediators for river systems, and the food source they provide for our aquatic mammals, little consideration has been given to managing rivers to ensure the ongoing health of mussel populations. To address concerns for their survivorship we collated data from a number of research projects across Australia.

Starting with data collected from the Hawkesbury-Nepean River in NSW in 2004/5 we used the von Bertalanffy growth equation to estimate site specific population structures for three species of mussels (Velesunio ambiguus, Hyridella australis and H. depressa). We used Leslie Matrices to model population projections for selected populations of these species over 10 years. Modelled scenarios included ongoing recruitment, reduced recruitment, and no recruitment - a situation indicated by some of the initial survey data. Much of the data required for accurately predicting population trajectories is simply not available for these species so we extrapolated data for similar species in the Avon River in Western Australia.

We resurveyed selected sites in the Hawkesbury-Nepean after about a decade, and found greatly reduced recruitment evidenced by changes in the population structures for species, or no recruitment at all. As well, there was considerable reduction in population densities for each species assessed. We believe this gives clear evidence of the decline in freshwater mussels, and that this is happening throughout our river systems across Australia.