I am sitting in my office in Cairns. When I look out of the window I can see dark clouds hanging in the sky, bringing with them the beginning of the wet season. As our remote field sites can only be accessed by dirt road, these clouds indicate the end of our field season 2016. But what an amazing year it has been!
In 2016, Sharks And Rays Australia commenced expeditions with volunteer field assistants. The response to our call for field assistants at the beginning of the year was fantastic, especially for the fact that this was our first year. People from all over Australia joined us in the field, many of whom were biologists.
We have also been joined by Indigenous Rangers in the field. SARA is now collaborating with five Indigenous Ranger Groups, and their help in the field is invaluable. These guys know their country like the back of their hand, and helped us overcome the many logistical challenges such as launching the boat in areas where there are no boat ramps. They also know which areas are inhabited by particularly large crocodiles and showed us how to read the depth of the river based on the surrounding terrestrial vegetation. Their interest in sawfishes and our research was also incredible, which is very encouraging. For example, the Kowanyama Land and Sea Rangers joined us in the field and on the boat, and almost every one of the Gangalidda-Garawa Land and Sea Rangers joined our presentation and induction. These collaborations make our work more fun and exciting but they are also important. After all, the majority of Queensland’s rivers in which sawfish are likely still abundant, are bordered by country that is under Native Title claim.
Together, we have discovered many amazing places in the Queensland tropics that are completely off the beaten track. We have commenced our study in seven rivers that all flow into the Gulf of Carpentaria, from near the Northern Territory border in the west to north of Weipa. We have experienced an abundance of wildlife, from swarms of grasshoppers, to snakes crossing rivers, to iconic Australian species such as goannas, kangaroos and emus. Our fieldwork was often done under the watchful eyes of saltwater crocodiles and wedge-tail or white-bellied sea eagles. We rescued blue-tongue skinks and pythons that were sunbaking on the roads, and stood in awe of corypha palms that were in bloom. How I miss sitting by the campfire and listening to the songs of whistling kites.
The landscapes we have worked in have been truly stunning and unique. From the endless salt marshes of the Nicholson River to the grasslands that surround the Mitchell River. But we have also seen at first hand the large-scale mangrove die-offs that nobody talks about. It is yet to be seen what these die-offs mean for so many fish and also sawfish that use these submerged forests as nursery grounds.
We also caught, tagged and released 49 elasmobranchs, belonging to seven different species. The most commonly caught sharks were juvenile bull sharks Carcharhinus leucas, with 25 individuals, followed by freshwater whip rays Urogymnus dalyensis, with 6 specimens. Sampling in coastal regions did not get us any of the elusive Queensland sawfish Pristis clavata or Green sawfish Pristis zijsron but we caught, tagged and released five freshwater sawfish Pristis pristis. The diversity of elasmobranch body shapes was reflected in our samples, with juvenile giant shovelnose rays Glaucostegus typus as well as juvenile eagle rays Aetobatus ocellatus being caught. But we have also found evidence of sawfish being finned – a practise that is illegal for anyone in Australia.
As we are not only aiming to understand our study species but also gain a better understanding of the ecosystems they occur in, we also analyse our by-catch, almost all of which was released alive. A total of 276 fish were identified, measured and released! By-catch was clearly dominated by fork-tailed catfish, and within that group Sciades paucus the shovelnose catfish took the lead. These results clearly show that gill nets and drum lines are only selective by size and not by species, but our sampling strategies have also proven to be effective in ensuring that most animals are released alive.
Our field assistants have brought many skills to our expeditions this year, and they have also learned many things, about our research, sawfish, our methods and also about themselves! Spending time in relatively untouched, remote ecosystems often brings us back to ourselves and exposes our strengths and fears. But as a team we can overcome these challenges and learn from each other.
In 2017 SARA will expand even more. We will continue to run our project on the assessment and distributions of sawfish and other sharks and rays in our study area. With this we will continue to collect DNA and stable isotope samples, and we are hoping to explore more rivers.
We will help Mangrove Watch assess the state of the mangrove forests that we work in, and we will commence sampling rivers for environmental DNA (eDNA) of sawfish, in collaboration with Prof. Colin Simpfendorfer from James Cook University.
We also hope to increase our presence in local schools, not only showing kids what we do but also introducing our food web game that will be developed in collaboration with Sharks4Kids.
We are hoping to commence trials for new methods of capturing sawfish. And hopefully SARA can grow, as we will be seeking students to take over some of our projects, like the stable isotope study of river food webs, and our accelerometer study of sawfish behaviours. So stay tuned, join our newsletter and regularly check into our facebook page!
The first time I saw a sawfish, I was mesmerised. The question that sprang instantly to mind – and also the one that I get asked the most – is, what is the saw used for? To say that I found this question fascinating is an understatement, as I spent four years of my life trying to answer it. My PhD project, which I finished in 2011, focused on the feeding behaviour and sensory biology of sawfishes. And I can tell you already, the deeper I got into the topic, the more fascinating it became.
The saw is an elongation of the rostral cartilage. The elongated rostrum, which also bears lateral teeth, evolved at least three times independently in elasmobranchs: twice in rays and once in sharks – in the family Sclerorhynchidae (extinct sawfish), the family Pristiophoridae (sawsharks) and the family Pristidae (living sawfish). For my research I compared sawfishes with their close relatives the shovelnose rays of the family Rhinobatidae. As both taxa are likely to have evolved from a common ancestor that was similar to shovelnose rays, the comparison enabled me to provide a hypothesis about the evolutionary benefit of the saw in living sawfishes.
My research found that the freshwater sawfish Pristis pristis uses its saw both to sense prey (via electroreception and touching) and to manipulate it. Interestingly, juvenile freshwater sawfishes slash at an electric dipole, which resembles visually hidden prey, only when it is suspended in the water. Shovelnose rays hardly react to these fields. When a sawfish encounters an electric dipole field on the bottom, just like a shovelnose ray it tries to gobble up the field source with its mouth. These results clearly indicate that the evolution of the saw enabled sawfishes to expand their hunting strategy to include fast, free-swimming prey.
The saw, however, is also what gets sawfishes into trouble. Saws easily get entangled in fishing gear and the sawfishes wrap themselves up even more in nets when they try to escape from the invisible danger, sometimes becoming dangerous to handle. Saws are also sought-after trophies. Even though all species of sawfish are listed on CITES and the four species in Australia are protected locally under federal and state legislation, saws can still sometimes be found for sale at local markets or on e-bay.
I had always thought that fishermen were taking whole sawfishes and selling the fins separately from the saws. After all, sawfish fins are among the most valuable in the international shark-fin trade and can fetch a few thousand dollars each. But there is a different, even more disturbing practice. Fishermen, both commercial and recreational, are cutting off a captured sawfish’s saw before releasing the animal alive. Although I had heard rumours about this practice, it was only in November 2015, when we finally ran the first research expedition with Sharks And Rays Australia to the Norman River, that I started to realise just how much of an issue it could be.
Situated in the south-eastern corner of the Gulf of Carpentaria, the Norman River is a Mecca for commercial and recreational fishermen who are after barramundi. It is fairly accessible, being one of the few destinations in the Cape York region that can be reached by a paved road. Moreover, public concrete ramps enable boats to be launched easily at Normanton, which lies inland on the river, and at the coastal fishing port of Karumba.
Setting, checking and retrieving gill nets in this river was an adventure. We were manoeuvring in waters with an average visibility of 10 centimetres (four inches). Hidden under the surface were landscapes of boulders, sunken logs and sand bars that were only visible with the aid of modern technology. The presence of large saltwater crocodiles took the required alertness and protocols to the next level. We had prepared for encounters with all kinds of creatures, from our study species to sand flies, mosquitoes, stingrays and stingers. What made the sampling even more difficult was that the river was full of jellyfish. Our net setting required fine-tuning.
After four days of sampling we managed to capture, tag and release one juvenile bull shark and one sawfish. I don’t think that this low sample number reflects the sawfish population of the Norman River, but it will take many more field trips to find out. As a result of our outreach efforts while we were at the Normanton Tourist Park, we received reports of two accidental sawfish captures that took place just days before we arrived. When the sawfishes were captured by recreational fishermen, the saws of both were already missing. The fishes were released alive, but their chances of survival are slim.
Together with the Save Our Seas Foundation Media Unit, the material submitted was turned into an educational video so that this sad occurrence could be turned into an opportunity for public education. Please share it widely.
Facts
In countries where sawfishes are protected, the removal of a sawfish’s saw is illegal.
As sawfishes are listed by CITES (the Convention on International Trade in Endangered Species), any international trade in sawfish body parts or live animals is regulated.
In Australia sawfish are protected under the EPBC Act.
When the saw of a live sawfish is removed, the brain cavity is opened, resulting in the sawfish’s slow, lingering death.
A sawfish uses its saw to find and manipulate its prey. It also uses it to defend itself.
Further reading Morgan DL, Wueringer BE, Allen MG, Ebner BC, Whitty JM et al. 2016. What is the fate of amputee sawfish? Fisheries 41(2): 71–73. Seitz JC, Poulakis GR. 2006. Anthropogenic effects on the smalltooth sawfish (Pristis pectinata) in the United States. Marine Pollution Bulletin 52: 1533–1540. Wueringer BE, Squire LJ, Kajiura SM, Tibbetts IR, Hart NS et al. 2012. Electric field detection in sawfishes and shovelnose rays. PLOS ONE 7: e41605. Wueringer BE, Squire LJ, Kajiura SM, Hart NS, Collin SP. 2012. The function of the sawfish’s saw. Current Biology 22: R150–R151.
Last week we were fortunate to visit Sue Ryan in her studio near Tomoulin, Far North Queensland. Sue had just finished her sawfish figure. It measures 4.5m long and was comissioned by the Glasgow museum. The frame of the sawfish was made from a chicken wire and bamboo. Its surface is made from ghostnet material that was collected along the coast line of the Gulf of Carpenteria. Sue picks the fibres apart and sews them carefully on the frame. Another artist, Ricardo Idagi from Murray Island, designed the pattern on the dorsal side of the sawfish. The project took seven months to complete.
The week after we visited, the sawfish was placed in a box and is now on its way to Glasgow. I am sure it will be the star of the collection!
‘So what do you do?’
‘I’m a biologist. I work with sawfish.’
‘Starfish, really? How exciting!’
‘No, no, SAWFISH! You know, its body looks like a shark’s, but it also has a long saw with teeth down the sides! Do you know what I mean?’
This is a conversation I have had many times. Although I could blame this little misunderstanding on the fact that my native tongue is German, over the 12 years that I have lived in Queensland and worked with sawfish, I have come to realise that there is also another, more important reason.
Many Queenslanders have never heard of sawfish. Even fewer people are aware of the fact that northern Australia, including Far North Queensland and the Cape York Peninsula, is probably the last global stronghold for four species of sawfish. This phenomenon may be explained by the low population density and little tourism of the Cape York region. Another reason could be that the rivers and coastal regions of Cape York, which sawfish inhabit, have very poor visibility and are a prime habitat of saltwater crocodiles. Unless you accidentally catch a sawfish in your recreational fishing gear, these creatures are likely to remain hidden from you during your visit to Cape York.
For these reasons, I started thinking about setting up an organisation here in Cairns that would actively engage the public in research on the elasmobranch fauna of Far North Queensland and the Cape York region. In 2014 I embarked on a long, unmapped and rocky road through bureaucracy that greatly resembled the unsealed roads leading to our remote research sites. At the beginning of 2015, Sharks and Rays Australia (SARA) was finally incorporated and early in that year we signed a partial sponsorship deal with Polycraft Australia and Mercury for a small research vessel.
During the set-up phase, it became clear that the involvement of Indigenous Rangers in the ecological surveys run by SARA would be crucial. Over the past decade, the strong connection of Indigenous groups to their country has been formally recognised under the Native Title system, which provides Indigenous groups with exclusive or non-exclusive rights over their land. Most of the Cape York territory is now covered by a patchwork of Native Title rights. There, many Aboriginal Land Councils now run Indigenous Ranger programmes to manage their country. Indigenous Ranger groups also run Junior Ranger programmes to pass both ecological and traditional knowledge on to the next generation.
In September 2015, while SARA’s research vessel was still caught up in the process of commercial registration and therefore not yet launched, we decided to embark on our first trip to Cape York – without a boat. But even though I was impatient to begin the actual research – from a boat – Cape York did not disappoint.
Kicking up the dust on the way to Kowanyama, Cape York Peninsula. Most roads on the Cape York Peninsula are unsealed.
We were heading to Kowanyama, the largest Indigenous Community on Cape York. The community is located on the west coast of the cape, on the eastern side of the Gulf of Carpentaria, and is home to five different Indigenous language groups. The Indigenous Rangers of the Kowanyama Aboriginal Land Council are actively conducting ecological surveys and habitat restoration programmes. The drive to Kowanyama from Cairns takes about 12 hours, as most of the 600 kilometres of roads are unsealed. Along the way, we encountered lots of the unique wildlife of the Australian outback.
Termite mounds cover the dry grass landscapes of Cape York.
The yellow spotted monitor Varanus panoptes is widely distributed across northern Australia. It can attain a total length of 1.4 metres.
The first night, we camped along the Mitchell River, about 250 kilometres inland of the Coral Sea in the east and the Gulf of Carpentaria in the west. Even here, at this dry campsite in the middle of the bush, we were reminded of the presence of sharks and rays in the rivers of Cape York. Next to our camping spot, we found the carcass of what was probably a juvenile bull shark hanging in a tree. With the fillets missing, it looked as if it had been left behind by recreational fishermen. Its presence in such a dry region made us marvel at the ecological adaptations of sharks and rays.
The mummified, incomplete carcass of what was probably a juvenile bull shark hangs from a tree. In the background can be seen the small waterholes that are all that remains of the Mitchell River during the dry season.
In Kowanyama, we received a warm welcome from the local Indigenous Rangers. They provided us with first insights into their ongoing habitat restoration and ecological survey programmes and we discussed the potential of future collaborations for sawfish surveys. Now, while we are working out the details of this collaboration, we eagerly await our return to this beautiful part of the Cape York region and hope to put Kowanyama on the map with sawfish encounters for our research.
Barbara Wueringer of Sharks and Rays Australia meets Garreth Forrester, the senior ranger of the Kowanyama Indigenous Rangers to discuss collaborative work to tag and release sawfish on the western side of Cape York, Queensland, Australia.
To keep up to date with Sharks and Rays Australia’s research projects, please follow us on Facebook or check out our homepage, where you can also submit sawfish sightings and subscribe to our newsletter.
Murdoch researchers highlight the cruelty of amputating sawfish rostra
February 18, 2016
A Green Sawfish with its rostrum amputated (Pic: David Morgan)
The cruel act of amputating distinctive sawfish rostra for trophies should be afforded the same attention as the poaching of body parts from other endangered species like rhinos, a Murdoch University researcher has said.
Associate Professor David Morgan from the Freshwater Fish Group & Fish Health Unit said sawfish protection needed better enforcement globally and the conservation value of sawfish should be actively promoted.
Available evidence suggests sawfish die a lingering death after rostrum removal, he said in an article published in the Fisheries journal.
Their rostra – the chainsaw-shaped extension that distinguishes the fish and gives it its name – are used to sense, forage for and capture their prey of crustaceans and small fish.
“Sawfish forage on the riverbed and sense prey via the electrosensitive pores on their rostra,” explained Dr Barbara Wueringer, who co-authored the study.
“They then slash their rostrums to stun or impale their food. They also use the rostrums to protect themselves from predators.”
Professor Morgan and his team studied the behaviour of a Green Sawfish found in the Ashburton River after its rostrum had been illegally amputated. They tagged it and observed changes in movement patterns and habitat use compared to similarly sized sawfish with rostra intact.
“We found that it ranged more widely, perhaps in order to source ‘easy prey’ or avoid attacks by predators, than other tagged sawfish of a similar size with rostra intact,” he said.
“After 75 days the fish was no longer detected and may have either emigrated outside the detection range or, more likely, it will have perished because emigration occurred infrequently for other tagged sawfish of that size.”
At a later date, Professor Morgan also captured and tagged a Freshwater Sawfish with a partially severed rostrum contained in an isolated freshwater pool in the Fitzroy River.
He said it was severely emaciated and its damaged rostrum had impacted its ability to effectively forage.
“It was detected by our loggers for 10 days and not thereafter. In comparison, two other similarly sized individuals tagged in the same pool at the same time were detected for several months. This supports our assumption that the injured sawfish died in the pool.”
Professor Morgan said the decline of sawfish due to fishing pressure was exacerbated by humans removing sawfish rostra.
“This undoubtedly negatively impacts survival rates of those fish,” he added.
“Most amputations in northern Australia are from the last few decades.
“The few remaining human population centres that have sawfishes inhabiting their local waters must address this destructive phenomenon, and sawfish protection needs better enforcement globally.”
