Croaker podcast
Croaker Podcast
in June 2020, James Donaldson from the Northern Gulf Natural Resource Management Group invited Dr Wueringer to join him for an episode of the Croaker podcast.
A rare insight into the habitat requirements of large Aussie sawfish
By Barbara Wueringer
Sawfish are very unique creatures, which sometimes poses problems when working with them. The saw of a large sawfish can easily be one the biggest safety hazard you will face during fieldwork. But these animals have another adaptation that has made it difficult to attach tags to them. As the animals often come into shallow waters they have the ability to loosen up their dorsal fins, allowing the fins to fall on the side.
When I worked with captive largetooth sawfish (locally in Australia known as freshwater sawfish) Pristis pristisa decade ago, I realized that in situations that I interpreted as likely stressful for the animals, their two dorsal fins would not stay upright anymore. In captivity these situations included water changes where the water levels in the tanks were first dropped and again raised.
In the wild, when juvenile sawfish venture into shallow waters of 20 cm depth or less, they could easily fall prey to terrestrial predators such as wedgetail eagles, which can reach a wingspan of 2.8m and are commonly encountered in the outback, and near rivers in Northern Australia. This means that it might not be stress, but the low water levels that caused the fins to drop!
The floppy fins pose some difficulties to attaching satellite tags to the dorsal fins of sawfish. The last time that sawfish in Australia, according to our knowledge, were tagged with satellite tags was in 2008 (Stevens et al. 2008). The authors tagged 7 sawfish (5 P. clavataand 2 P. zijsron) with SPOT tags that were bolted to the tip of the dorsal fins of sawfish. These tags are commonly used on sharks, and they can only connect to a satellite and send a location point when the dorsal fin breaks the surface. Additionally one pop-up satellite archival tag was put on another P. clavata. While the PAT tag provided depth data and popped off from the animal after 49 days within a few km of the tagging location, the SPOT tags only provided a handful of locations each (Stevens et al. 2008).
Dr Wueringer holds a towed SPOT-253 tag from Wildlife computers that has been attached to a sawfish. Note the first dorsal fin of the animal falling to the side.
The dwarf sawfish that has been tagged is ready to be released.
Since then, satellite tagging of sawfish has come a long way, and thankfully with the information provided by our American colleagues, our tagging has been more successful. They successfully trialled the methods of attaching towed tags to large smalltooth sawfish Pristis pectinata (for more info see Carlson et al. 2014, Guttridge et al. 2015, Papastamatiou et al. 2015) and shared their set up with us.
The next challenge for us was to find sawfish that were healthy (i.e. did not have their saws amputated) and large enough to tow the tags. In March 2019 it finally all came together and we were able to deploy two of our towed SPOT (smart position and temperature) tags! The first one was deployed on a 280cm long, and likely sexually mature female, Dwarf sawfish Pristis clavata and within 24 hrs the second tag was deployed on a 300cm long juvenile green sawfish Pristis zijsron.
One tag detached after about 3 months while the other one stopped sending location data 10 months after deployment. However, while the analysis and project is still ongoing, we can already see that the data we have received is amazing.
One of the most important outcomes of the tag deployments is that we were working with a commercial fisher on this expedition, who now knows how to deploy tags for us and is excited to do so. So we hope that the next tags won’t have to wait another 3 years to be deployed, as we all work together to find large sawfish.
This image shows a subset of the raw location fixes that we received from our tagged green sawfish. Each dot represents a location fix. Location fixes can have errors (including land based locations), especially when a tag does not surface long enough to send its data to the satellite.
This project has received funding by the Save Our Seas Foundation, the Seaworld Research and Rescue Foundation Inc., the Shark Conservation Fund and the Sydney Aquarium.
This blog post was originally written for the Save Our Seas Foundation. you can access the original here.
References
Carlson, J. K., Gulak, S. J. B., Simpfendorfer, C. A., Grubbs, R. D., Romine, J. G. and Burgess, G. H. (2014). Movement patterns and habitat use of smalltooth sawfish,Pristis pectinata, determined using pop-up satellite archival tags. Aquatic Conserv. Mar. Freshw. Ecosyst.24, 104-117.
Guttridge, T. L., Gulak, S. J., Franks, B. R., Carlson, J. K., Gruber, S. H., Gledhill, K. S., Bond, M. E., Johnson, G. and Grubbs, R. D. (2015). Occurrence and habitat use of the critically endangered smalltooth sawfish Pristis pectinata in the Bahamas. J Fish Biol87, 1322-1341.
Papastamatiou, Y. P., Dean Grubbs, R., Imhoff, J. L., Gulak, S. J. B., Carlson, J. K. and Burgess, G. H. (2015). A subtropical embayment serves as essential habitat for sub-adults and adults of the critically endangered smalltooth sawfish. Global Ecology and Conservation3, 764-775.
Stevens, J. D., McAuley, R. B., Simpfendorfer, C. A. and Pillans, R. D. (2008). Spatial distribution and habitat utilisation of sawfish (Pristis spp) in relation to fishing in northern Australia. 26.
An important meeting
by Barbara Wueringer
In December 2019 I had the opportunity and pleasure to meet Dr Sally Box, Australia’s Threatened Species Commissioner.
We talked about sawfish research and conservation in Queensland, and I provided her with insights into our work and our collaborations with Indigenous Rangers. The meeting went incredibly well. Colleagues from Cape York Natural Resource Management and Northern Gulf Resource Management Group were also present, and I think we got Sally excited about these magnificent animals.
I was also able to make Sally aware of how sawfish fall through the cracks when it comes to funding opportunities from the Federal and Queensland governments. Australia’s Threatened Species Recovery Strategy, for example, only mentions birds, mammals and plants. Many funding rounds that open, including the last endangered species grant round, are specifically targeting recovery actions and outcomes for terrestrial mammals and birds, thus not allowing grant applications for aquatic endangered species to be considered. Sally was very interested to hear that, as her Department is currently working on the next Threatened Species Recovery Strategy, and we hope that this will take fish into account.
At some point Sally congratulated me for how much work SARA has done with how little funding. And I would like to throw this huge THANK YOU right back at everyone who has helped us, volunteered their time, helped us fund our work, or even just came on board to discuss ideas, read drafts, and help steer SARA!
We could not do without our students, volunteers, field assistants, colleagues, rangers and interns. All these times spent sampling, driving, sweating, swearing, bonding, sitting around the fire, laughing, covered in mud, tired, longing for a hot shower, McGyvering our way through problems in remote regions are worth it.
After our meeting Sally had some very kind words for us.
Turning trophies into messengers for conservation
by Nikki Biskis and Barbara Wueringer
We are excited to announce that a long imagined SARA initiative is well underway! Since commencing our public submissions campaign in 2016, we have received over 140 sawfish saws in donation. Some of the saws are used for school visits and species ID workshops, but we are now on a mission to display the majority of saws all over Far North Queensland. This is our chance to turn saws once removed as trophies into messengers for conservation!
Right now we are designing and building informative displays to educate communities about how to safely release sawfish from fishing gear and report sightings to us. Our conversations with people from all walks of life have shown that once people understand how threatened sawfish are, they become stewards for these amazing animals. Ensuring that the saw is not amputated from an accidentally captured sawfish is one of our priorities.
So far we have received funding from the Advanced Queensland Citizen Science Initiative for the first 25 locations, with an ultimate goal of reaching 50. SARA has also received overwhelmingly positive feedback from the locations contacted so far. We have officially picked the first 20 locations, and most of them are already on board! Thank you to everyone that offered to be a part of our mission! If you think that your location (iconic pub, road house, tourist info centre and more) sees large numbers of both tourists and local visitors, and would like to join this project, please send an email to nikki(at)saw.fish
Both the Sawfish Biology Guide and Display Flyer were designed with this project in mind
Currently planned locations for sawfish saw displays: Albatross Bay Resort (Weipa), Daintree Discovery Centre (Daintree), Barramundi Discovery Centre (Karumba), Cape York Peninsula Lodge (Bamaga), Lakeland Hotel (Lakeland), Moreton Telegraph Station (-12.4536°, 142.6386°), Cardwell Rainforest and Reef Visitor Information Centre, Cairns Aquarium, Normanton Library/Info Centre, Kowanyama Ranger Office, Kowanyama PCB, Nature’s Powerhouse (Cooktown Visitor Information), Hann River Roadhouse (-15.1889°, 143.8725°), Palmer River Roadhouse (-16.1070°, 144.7769°), Archer River Roadhouse (-13.4376°, 142.94168°).
Unexpected mail
by Nikki Biskis
In September 2018, SARA received what is probably the cutest scientific interview of all time. Billy, Charlie, Dylan and Jayden of Birmingham Primary School in Mount Evelyn, VIC, had some very creative questions regarding sharks and rays. So, naturally, four lucky biologists from the SARA team responded right back to these curious minds. Some of our favourites are below!
- Do some sharks fight?
Sharks do not really fight very often but bigger sharks do scare off smaller sharks. If two sharks are swimming straight towards each other the smaller shark is the one that will move out of the way to let the big one carry on swimming. Big sharks can also eat small sharks!
- Do sharks mean to eat people?
No! Unlike humans, sharks don’t have any hands, so they can’t pick things up to figure out what they are. Instead they take a bite. Only once they take a taste of something can they be sure of what it is. Humans are not on the normal menu for sharks. So usually once they taste us they don’t want another bite.
- Do sharks smell oil?
Sharks have an incredible sense of smell, so it is very likely they can smell oil. Nearly two thirds of a shark’s brain is for thinking about smells and they can sniff out just one teaspoon of fish blood from a swimming pool sized area of water.
