Document ID: chunk:federal_register_of_legislation:F2015L01763:reg:2:p5
Version: federal_register_of_legislation:F2015L01763
Segment Type: reg
Provision Reference: reg 2 (pt 5/5)
Character Range: 19351–20377

Phillips, 2012). Unlike the largetooth sawfish, neither the green sawfish nor dwarf sawfish exhibit large-scale sex-biased dispersal in Australian waters. Although the locations and the nature of the boundaries of these population regions remain unknown, the implication is that local population declines or extinctions will not be replenished in the short to medium term through immigration.
There has been no genetic research into the population structure of the river sharks, which makes it difficult to determine if the identified populations mix, and if they do the extent of their mixing.

     2.6                Population trends
There is limited information on current population sizes or trends in Australian waters for these species, but there is evidence that all species have experienced recent population declines and some species are considered to have been extirpated from former parts of their range. Remaining populations are often isolated, raising concerns about their viability (DSEWPaC, 2011; DoE, 2015).