A rare insight into the habitat requirements of large Aussie sawfish

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., 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

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

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 50SARA 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

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!

  1. 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!

  1. 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.

  1. 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.

Go Fund Me

Go Fund Me

Since 2015, Sharks And Rays Australia is working with sawfish in Queensland. They are globally critically endangered. We spend about 3 months in the field every year, sampling for these animals in some of the most remote sites in Australia. On every field trip we visit a remote school, and when possible we work with the local Indigenous Land and Sea Rangers to increase their knowledge on sawfish and how to look after these animals. We also work with commercial fishermen to create a sustainable model of conservation that also maintains healthy fisheries.

In July 2019, we had a car accident on our way to our field site. Luckily nobody was injured but our amazing expedition vehicle, a Landcruiser Troopcarrier, was destroyed. While the insurance has paid out what they consider the market value to be, it does not even cover half of the cost of a replacement car, let alone fitting out the car to be field ready.

Please help us! Anything counts towards our goal – so remember, no donation is too small!

If you are a sawfish hero or business, from a donation of A$ 750 onwards we will add your sticker on the back of our expedition vehicle, for all of remote Queensland to see. For donations above A$ 3000 you will be allowed to name one of our satellite tagged sawfish and receive a certificate and 3 updates on its whereabouts. For donations of or above A$ 5000 you will be mentioned as a sponsor on our homepage for 2020! If you are representing a business please contact Barbara@saw.fishto check that our values align.

Thanks so much everybody, together we can make a difference!

Please find our Go Fund Me campaign here https://www.gofundme.com/f/83kgqv-help-sawfish-research-team-get-back-on-the-road

 

Commercial Fishers Showcase Their Sawfish Release Skills

Commercial Fishers Showcase Their Sawfish Release Skills

By Veronika Biskis

Sawfish populations are receding to some of the most remote areas in northern Queensland. SARA works with sawfish in Queensland on a large geographic scale, and we are fortunate to have incredible partners that dedicate both time and money in conducting these surveys. In addition, crucial information comes from submissions from past and present fishers and their families. With sawfish becoming quite rare, these reports from citizen scientists are an important part of our assessment of sawfish range and distribution.

But what actually happens when a sawfish is caught in a commercial gill net? It is one thing to set one with the specific purpose of research – the team is trained in sawfish release and are prepared for the next steps. This is a different scenario when they wind up as by-catch. While sawfish are not readily seen to the sizes reported back in the 70s and 80s, animals around the 5m mark are still occasionallycaught. Fishers report they thrash wildly, often becoming further and further ensnared. Evidence has shown that sawfish can last for hours in a net as long as it isn’t wrapped around their gills. However, once they are taken out of the water for removal they suffocate – hence their understandably severe reaction. How can commercial fishers release a sawfish in a matter of seconds, without causing injury to themselves, the net, and the sawfish?

Karumba is a small fishing town situated where the Norman river meets the Gulf of Carpentaria, truly the ‘outback by the sea.’ It is also the meeting place of the annual meeting of the Gulf of Carpentaria Commercial Fishermen Association Inc., which SARA was invited to attend this October. As the accidental by-catch and safe release of sawfish is likely the most dangerous occupational hazard for commercialgill netters, SARA held a unique contest asking fishers to showcase their handling skills. We got a first-hand look at how sawfish are removed from the net on the job.

Anoxypristis saw entangled in a gill net, at the start of experimental trial. Image by Nikki Biskis, SARA

Our experiment yielded some exciting preliminary results:

  • Releasing sawfish is like riding a bicycle! The longest career fishers were able to remove saws the fastest, even if the fishers had been out of the game for over 10 years.
  • Every top competitor used a different removal tool, ranging from varioustypes of barra hooks to a screwdriver.
  • Skills are passed down from families and former skippers. Deck hands on the same boat tended to use the same tools.
  • The fastest time of release was 39 seconds!

    There are not many places in Queensland where you can see a sunset over the sea, and Karumba is one of them. Image by Nikki Biskis, SARA

Through conversations with fishers we learned that many employ tonic immobility, where they flip the sawfish on their back to calm them. Many fishers had learned this on the job, and did not know that this technique had a name. All had amazing stories to tell of their experiences with sawfish – for example, some talked about seeing them hunt first hand. This behaviour in the wild has never been captured on video.

This is a first step in our initiativeto develop materials to help train future fishers in the proper release of sawfish in the wild. In addition, it reiterates the importance of commercial fishers as sawfish advocates, potentially holding the key to their survival. Who better to safely tag and release sawfish than those who regularly handle them? Thirty years ago, this contest may well have been met with laughter – why not just shoot it? But nowadays, with fishers still active, who have seen sawfish numbers drop over the last decades, we can all work together to develop fishing practises to better protect the waterways and the crucial species living in it.