Kinship in the Kimberley: the genetics of dwarf and green sawfish
Sawfish are among the most threatened vertebrates on the planet, and some regions of Australia are where the last viable populations of dwarf and green sawfish remain. But Jack wants to know if these populations are genetically healthy; what is the risk of inbreeding when numbers have dwindled drastically, globally and locally? He is inferring kinship within and among dwarf sawfish in the Kimberley region, Western Australia, and investigating their philopatry and reproductive behaviour. He is also exploring genetic variation and inbreeding for the green sawfish in the Pilbara region to assess the health and recovery potential of populations.
Jack Ingelbrecht
I grew up in the hills of Perth, Western Australia. When I was seven, every kid in our class had to do a video assignment for school. We each got to choose our own project and I decided to do mine on sharks and rays because it seemed like a good excuse to get my dad to take me to the big aquarium on the other side of the city. It worked! I still remember wandering through the premier reef tank exhibit, watching through the glass as the scuba divers hand-fed a shiver of grey nurse sharks. When...
Insights into population genetics and reproductive behaviour of Critically Endangered sawfishes in northern Australia
To assess kinship and population genetics in globally important populations of dwarf sawfish and green sawfish in northern Australia.
Conservation efforts for the dwarf sawfish and green sawfish are hindered due to data deficiencies in numerous aspects of their biology and ecology, and the health of remaining populations. This project is important for identifying biologically meaningful populations and assessing their potential for recovery. Furthermore, genetic techniques offer the most effective means to investigate kinship and, by extension, reproductive behaviour. This information is essential for conservation efforts and establishing effective management strategies.
The dwarf sawfish Pristis clavata and green sawfish P. zijsron are among the world’s most threatened marine species. These iconic, large-bodied rays primarily occupy tropical coastal waters, which are often subjected to disproportionately high levels of fishing pressure and disturbance. Populations of dwarf sawfish and green sawfish have declined drastically over the past century, mainly due to overfishing, since their denticle-toothed rostrum makes all sawfish species highly susceptible to capture in fishing nets. Currently, viable populations of dwarf sawfish and green sawfish are limited mostly to northern Australia. Populations on the west coast are genetically more diverse than, and distinct from, populations in the Gulf of Carpentaria or east coast, which makes the populations in Western Australia of global conservation significance. However, while threatened species assessments indicate that the dwarf sawfish and green sawfish face a relatively low risk of extinction in Australian waters compared to most other areas throughout their distributions, populations that have experienced a decline remain susceptible to genetic drift and inbreeding, which may compromise their viability.
The integration of genetic information into species management has the potential to greatly enhance conservation strategies for these sawfish species. The dwarf sawfish is the most understudied of the sawfish species and little is known about its reproductive biology or genealogical relationships (i.e., kinship) within remaining populations. Furthermore, the extent of genetic variability within and between populations of green sawfish in Western Australia is mostly unknown, including in the Pilbara region, one of the most important hotspots for this species. Genetic approaches offer perhaps the most effective means to bridge these data gaps, particularly for inferring kinship, as it is almost impossible to obtain data for wild populations from direct observations alone. This research will provide much-needed insight into genetic variability for the dwarf sawfish and green sawfish in Western Australia and will thus contribute to more effective conservation.
- To infer kinship within and among populations of the dwarf sawfish in the Kimberley region and to investigate philopatry and reproductive behaviour of this species.
- To investigate the extent of genetic variation and inbreeding in the green sawfish in the Pilbara region and assess the health and recovery potential of populations in this region.