Species we encounter – Rhinopristiformes

Species we encounter – Rhinopristiformes

by Amica Limosani, Jake New, Barbara Wueringer

The Rhinopristiformes are an Order of elasmobranchs that comprise shark–like rays. They can be identified by their flattened, either disc– or diamond–shaped heads and shark–like bodies. Common names of this order include guitarfish, sawfish, and shovelnose rays. Rhinopristiformes inhabit warm, shallow waters, making them particularly susceptible to being caught in fishing gear. Unfortunately, global shark–like ray populations are declining due to the combined effect of bycatch in fisheries and targeted fishing for their large fins on the black market. These unique animals need conservation advocacy to restore their populations to healthy levels. SARA’s long-term research and advocacy on sawfish have informed various fisheries’ legislations, leading to increased populations!

Bottlenose Wedgefish, Rhynchobatus australiae

Get to know the Bottlenose Wedgefish (Rhynchobatus australiae). With their unique wedge-shaped bodies and elongated snouts, these rays are true ocean wonders. Found in shallow coastal waters and coral reefs across the Indo-Pacific, they expertly blend into sandy or muddy substrates as they hunt for prey. Sadly, these fascinating creatures are critically endangered due to overfishing and habitat degradation, making conservation efforts vital (learn more about it by reading a paper by Kyne, 2020).

Eyebrow Wedgefish, Rhynchobatus palpebratus

Ever heard of a shark with eyebrows? Meet the Rhynchobatus palpebratus also known as the Eyebrow Wedgefish. Named for the prominent ridges above their eyes that resemble eyebrows, these unique creatures grace shallow coastal waters and muddy estuaries. With their distinctive wedge-shaped bodies, broad flattened heads, and elongated pectoral fins, they’re a fascinating sight to behold. Sadly, like many wedgefish species, eyebrow wedgefish are threatened by overfishing and habitat destruction, highlighting the urgent need for conservation efforts. Find out more about the conservation status on the IUCN page

Green Sawfish, Pristis zijsron

Ever seen a green giant with a built-in saw? Meet the Green Sawfish, Pristis zijsron. These unique creatures, one of the largest sawfish species, have a long, narrow rostrum and olive-green color. They live in shallow coastal waters and estuaries, often near mangrove forests in tropical and subtropical regions. Using their rostrum like a sword, they skillfully slash back and forth to capture fish, crustaceans, and mollusks. Sadly, these sawfish are critically endangered due to overfishing and habitat loss. 

 

Freshwater Sawfish, Pristis pristis

Meet the Freshwater Sawfish, Pristis pristis, also known as the largetooth sawfish. These creatures are among the largest species of sawfish, boasting long, flat rostrums lined with sharp teeth-like structures. They thrive in freshwater and brackish habitats like rivers, estuaries, and coastal lagoons, yet they’re also known to venture into saltwater environments. They journey between freshwater and marine domains for breeding and feeding. Sadly, their populations have plummeted due to overfishing, habitat loss, and bycatch, rendering them critically endangered. 

Dwarf Sawfish, Pristis clavata

The Dwarf Sawfish, Pristis clavata, is called dwarfs as saw is smallest in relation to body size. Despite their saws being the smallest in the Pristis family, they can still reach lengths of up to 3.1 meters and live for over 50 years.  Did you know that the “teeth” on their saw are specialized dermal denticles? These sawfish use their saws to detect, stun, and capture prey with incredible precision.  Keep an eye out for the gill slits on the underside of their bodies, a distinctive feature of these fascinating creatures

 

Narrow Sawfish, Anoxypristis cuspidata

We all recognise this ray, the narrow sawfish (Anoxypristis cuspidata). As the most abundant species of sawfish in Queensland and the only one in its genus, it stands out distinctly. This remarkable species has five canals in its rostrum, compared to the three in the freshwater sawfish. Found in tropical and subtropical coastal waters, these sawfish explore mangrove estuaries, rivers, and shallow bays. When hunting, they are masters, using their rostrum to stun and capture small fish and crustaceans. They are also known to feed on squid! However, these incredible creatures are critically endangered due to overfishing and habitat degradation. They need our help now more than ever.

 

Giant Shovelnose Ray, Glaucostegus typus

Meet the remarkable Giant Shovelnose Ray, Glaucostegus typus. With their distinctive shovel-shaped snouts, these rays are sand-sifting experts, constantly searching for prey in coastal waters near coral reefs and estuaries. Their striking coloration of dark upper bodies and white undersides provides excellent camouflage against the sandy seafloor. As nocturnal predators, they navigate the depths under the cloak of darkness, making every encounter with these ocean giants an unforgettable experience! Fun fact: our principal

Learn more about the Carcharhinid sharks we encounter here

Learn more about the Sphyrnid sharks we encounter here

Learn more about the Mylobatiform rays we encounter here

Species we encounter – Sphyrnids

Species we encounter – Sphyrnids

by Amica Limosani, Jake New, and Barbara Wueringer

Sphyrnid sharks, or hammerheads, include 10 species, all characterized by their iconic flattened and elongated cephalofoil, or “hammer” head. Their cephalofoil makes them highly effective predators by providing better maneuverability, a larger surface area for increased electroreceptors, nostrils that are further spaced apart for detecting prey, and possibly allowing them to pin down prey before biting. Hammerheads inhabit tropical and temperate marine waters and are famous for forming large migratory schools. Observing these migrations is a rare and remarkable experience!
Scalloped Hammerhead, Sphyrna lewini

Get ready to meet the Scalloped Hammerhead. These sharks are easily recognisable by their distinctively scalloped-shaped head, with eyes positioned at the outer edges. They’re not shy about their love for warm coastal waters and oceanic islands worldwide, often forming large schools near underwater seamounts and reefs. But here’s where things get interesting: these hammerheads aren’t just solitary swimmers. They’re known for their unique social behaviour, with schools comprised of hundreds to thousands of individuals. As apex predators, they rule the underwater realm, feeding on various prey, including fish, squid, and crustaceans, which gives them a crucial role in maintaining marine ecosystems’ health.

Great Hammerhead, Sphyrna mokarran

Say hello to the fascinating Great Hammerhead, Sphyrna mokarran! These ocean titans are the largest species of hammerhead shark, instantly recognisable by their “hammer” shaped heads, or cephalofoils. Roaming warm coastal waters worldwide, great hammerheads are master hunters. They use their wide heads to pin down and manipulate prey like stingrays and smaller sharks. They have eyes set wide apart and excellent vision for scoping out the seafloor. In Queensland, they are often seen in shallows as they hunt rays and can sometimes be mistaken for sawfish. However, their dorsal fins can help distinguish between the two. If you are ever in doubt, submit your sighting to www.cytags.com, and we will clarify it for you!

Winghead Shark, Eusphyrna blochii

Have you ever seen a shark with wings? Meet the Winghead Shark, Eusphyrna blochii. Known for their unique “wing-shaped” heads, which can be up to 1/3 of the shark’s length in width, these sharks have a flattened and laterally expanded cephalofoil as part of the hammerhead family. They inhabit shallow coastal waters and estuaries throughout the Indo-Pacific region, winghead sharks are a sight to behold. They are the smallest of the hammerhead family. Their specialised head shape helps them detect and capture small fish and crustaceans more efficiently

Learn more about the Carcharhinid sharks we encounter here

Learn more about the Mylobatiform rays we encounter here

Learn more about the Rhinopristiform rays we encounter here

The journey continues: Back in the city with more teeth

The journey continues: Back in the city with more teeth

Figure 1. Samples, polished, slided and ready for analysis! Image by Nikki Biskis.

By Nikki Biskis

And now the moment of truth! I am currently at the University of Adelaide, working at Adelaide Microscopy, where a spot and/or line along each sawfish tooth is vaporised via a laser and then the chemical composition read in a process called Induction Coupled Plasma Mass Spectrometry (ICPMS).  

 

Preliminary Findings  

Last year around this time, I ran a pilot study of 40 spot tests, transect analyses, and even complete mapping of individual sawfish teeth. Preliminary results indicated that trace element analysis can resolve the origin at the regional level, potentially narrowing down the capture location by hundreds of kilometres. This precision allows for more accurate incorporation of rostra data into risk maps, highlighting areas where sawfish populations are most vulnerable to ongoing fishing pressures. Now, with further funding from Holsworth and Save Our Seas, we can run the remaining samples and hopefully home in even further. 

 

Figure 2. Our 2024 run, ready to go. Image by Nikki Biskis.

What’s next? 

As I eagerly await the full results, the question remains: What works, and what still needs investigation? The higher precision spatial data will contribute to the development of targeted conservation strategies, ensuring the long-term survival of sawfish in their northern Australian stronghold. It’s an exciting journey that not only deepens our understanding of these Australian icons but also continues momentum in innovative approaches in conservation. 

 

Thanks laser – I’m happy to be here too. Image by Nikki Biskis.

And now, the best bit – on to stats. If you’re headed to the Australian Society of Fisheries Biology Conference in November, make sure to come say hello. 

This project is funded by the Holsworth Grant through the Ecological Society of Australia and the Save Our Seas Foundation. We’d like to additionally thank the Queensland Department of Agriculture and Fisheries for their ongoing support of our work. This work would also not be possible without the time and expertise of the team at the Gillanders lab at the University of Adelaide, namely Dr Patrick Reis-Santos and Rhiannon Van Eck, and Dr Paul Olin and Dr Sarah Gilbert at Adelaide Spectroscopy. 

You can read this blog and more on the Save Our Seas Foundation website.

 

Unveiling the Secrets of Sawfish: A Journey through Chemical Fingerprints and Conservation

Unveiling the Secrets of Sawfish: A Journey through Chemical Fingerprints and Conservation

By Nikki Biskis

Sawfishes are iconic species that embody many of the challenges faced in marine conservation. Despite comprehensive protection measures across various levels in Australia, their populations remain under threat from bycatch and illegal fishing for their fins and rostra. Unfortunately, the confiscated or forfeited trophy rostra available for research often come with little to no associated location data. This severely limits their potential for distribution analyses, which are critical for effective conservation strategies. 

 

The Research Journey 

As a PhD student at the University of the Sunshine Coast (UniSC) and the non-profit organization Sharks And Rays Australia (SARA), one of my research aims is to address this challenge. This project evaluates the use of trace elemental analysis to identify capture locations and origin estuaries for narrow (Anoxypristis cuspidata), green (Pristis zijsron), and freshwater (Pristis pristis) sawfishes along the Queensland coast.  

 

Methodology 

All the rostra used in this research were received through a collaboration by SARA and the Queensland Department of Agriculture and Fisheries (QDAF). At SARA, over the last two years, I’ve taken teeth from over 200 of these.  

 

Figure 1. (Left) My first attempts at taking teeth were a bit gruesome and may or may not have given Barbara a heart attack. (Right) We’ve now refined our methods so that sampling scars on saws used for education or that belong to other institutions are more subtle. Image by Nikki Biskis

Figure 2.Our health and safety officer during tooth removal. Image by Nikki Biskis

Trace elements such as strontium, barium, etc. vary in the environment due to salinity, temperature, upwelling, runoff – all these factors give an estuary a unique chemical fingerprint. So, by measuring the quantities of these through just a tiny spot at the base of each tooth, we can use the chemical signatures to assign them to an origin estuary. This is a common technique amongst bony fish but is relatively new amongst sharks and rays. 

If we take a transect, or line along the length of the tooth, we can see fluctuations due to these changes in the environment, allowing us a look into how the animals are moving, how they use their habitat. This is especially meaningful, as sawfishes are now rare, so while it might sound strange, a tooth might provide some of the most in depth insights into the spatial use patterns of these species. 

 

Figure 3. The teeth were then cleaned, epoxied, sectioned, and polished at UniSC. Image by Nikki Biskis

What’s more, a subset of the samples was taken from an entire animal, meaning we have the vertebrae – the stock standard for aging sharks and rays – as well. This means I have the very exciting side quest of investigating teeth as potential aging structure, through comparison of visual banding and elemental signature across the two sources.  

In other words, the teeth may hold the key to using these trophy rostra for conservation, protecting future populations. 

You can view this blog and more on the Save Our Seas Foundation website.

 

All species of sawfish are now globally Critically Endangered

All species of sawfish are now globally Critically Endangered

In 2022 the reassessments of all four species of sawfish under the criteria of the IUCN (International Union for the Conservation of Nature) Redlist commenced, and it was a global effort. Sawfish researchers from all over the world worked together to identify and assess the current distributions, habitats and ecology, population status, as well as ongoing threats for all five species.

Sadly, since the last assessments of sawfishes, in many regions the threats posed to these bizarre fishes have not declined and as a result all five species are now considered as globally Critically Endangered. With Australia being home to the last significant populations of four species of sawfish, what happens here matters greatly. While some species are still found in other countries, and for example freshwater sawfish Pristis pristis are being rediscovered in Central America, the genetic diversity in Australian populations of this species needs to be protected.

The assessments are comprehensive and in-depth. They represent a good starting point for anyone who is interested in understanding these species better.

Freshwater sawfish – Pristis pristis

Espinoza M, Bonfil-Sanders R, Carlson J, Charvet P, Chevis M, Dulvy NK, Everett B, Faria V, Ferretti F, Fordham S, Grant MI, Haque AB, Harry AV, Jabado RW, Jones, GCA, Kelez S, Lear KO, Morgan DL, Phillips NM, Wueringer BE. 2022. Pristis pristisThe IUCN Red List of Threatened Species 2022: e.T18584848A58336780. Link

Dwarf sawfish – Pristis clavata

Grant MI, Charles R, Fordham S, Harry AV, Lear KO, Morgan DL, Phillips NM, Simeon B, Wakhida Y, Wueringer BE. 2022. Pristis clavataThe IUCN Red List of Threatened Species 2022: e.T39390A68641215. Link

Green sawfish – Pristis zijsron

Harry AV, Everett B, Faria V, Fordham S, Grant MI, Haque AB, Ho H, Jabado RW, Jones GCA, Lear KO, Morgan DL, Phillips NM, Spaet JLY, Tanna A, Wueringer BE. 2022. Pristis zijsronThe IUCN Red List of Threatened Species 2022: e.T39393A58304631. Link

Narrow sawfish – Anoxypristis cuspidata

Haque, A.B., Charles, R., D’Anastasi, B., Dulvy, N.K., Faria, V., Fordham, S., Grant, M.I., Harry, A.V., Jabado, R.W., Lear, K.O., Morgan, D.L., Tanna, A., Wakhida, Y. & Wueringer, B.E. 2023. Anoxypristis cuspidataThe IUCN Red List of Threatened Species 2023: e.T39389A58304073. Link

Smalltooth sawfish – Pristis pectinata

Carlson, J., Blanco-Parra, MP, Bonfil-Sanders, R., Charles, R., Charvet, P., Chevis, M., Dulvy, N.K., Espinoza, M., Faria, V., Ferretti, F., Fordham, S., Giovos, I., Graham, J., Grubbs, D., Pacoureau, N. & Phillips, N.M. 2022. Pristis pectinataThe IUCN Red List of Threatened Species 2022: e.T18175A58298676. Link