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.

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.

 

 

Let’s stop the blame game and start collaborating!

Let’s stop the blame game and start collaborating!

In Australia, we have a responsibility to look after our four species of sawfish. Sawfish are the most endangered of all sharks and rays globally. Northern Australia is the last global stronghold for four out of five species.

For this year’s International Sawfish Day, some major media outlets became interested in Australian sawfish. These animals are receiving a lot of media attention recently, and with this comes a network of opinions and agendas. Because of these two recent articles on ABC and in the Guardian Australia, which present and also intermingle a lot of different view points, I would like to elucidate the direction of Sharks And Rays Australia in this field.

For the last 5 years, under my lead, SARA has worked with sawfish in Far North Queensland, the Gulf of Carpentaria and the Cape York Peninsula. Our philosophy for sawfish research and conservation is that ‘it takes more than a village’ to bring sawfish numbers back and we need everyone involved. Now, if you are one of the fishers who say that you still see plenty of them, I might ask you to take a look at our species ID flyer. Right now, we are mainly concerned with the three Pristis species, which take 8-10 years to become sexually mature. Anoxypristis (narrow sawfish, slimy’s) mature after 3 years and are thus still found in higher numbers. But even Anoxypristis is in trouble. In 2016 we found fins from this species on a drying rack in the Gulf of Carpentaria, and in 2018 we had a sighting of a sawless individual from the east coast submitted to us. If you regularly see large numbers of the other species, please report them to us!

In Australia, sawfish are federally protected on the EPBC Act and in Queensland they are also protected under the Fisheries Act, which means that from a legislative perspective, they are well covered. But once you spend time in remote regions, talking and working with station managers, Indigenous Rangers and fishermen, a whole different picture emerges. Everyone has a story to tell, of how they used to catch ‘really big ones’, but haven’t seen a single animal in 10-15 years. And everyone has someone else to blame for this.

The reality is that every single person who took a sawfish saw as a trophy contributed to the species’ declines. But while pointing the finger only creates scapegoats, anger and an outlet, it does not help sawfish. These animals continue to fall through the cracks. Instead of judging the past it is more helpful to take responsibility and change the future.

And in this, everyone has a role to play:

  • Our regular visits to schools have led to the collaborative development of materials. The Normanton State School has taken the life cycle up in its curriculum, and last time we visited they baked a sawfish shaped cake. Love your work!
  • We also work with commercial fishers. So far, I have only collaborated with a handful of fishers, but these guys are now putting tags on sawfish for us and releasing them alive. They are happy to go out of their way to release a 4m sawfish, even when working by themselves. Needless to say, this can be very dangerous as sawfish use their saw to defend themselves and such a large animal can hurt people.
  • We are always on the hunt for sawfish sighting submissions from the general public and recreational fishers. The old records that you have at home are important for sawfish conservation. We do not judge people who are in the possession of old saws, it is pretty clear that everyone used to take them as trophies. But it is important that this practise stops, as most animals will not survive this illegal procedure and their saw is much more important then as a dust collector. Your sawfish sighting submissions have already allowed us to show that the historic range of freshwater sawfish was larger than previously assumed, as they occurred near Brisbane.
  • Our field assistants are not shy to join us on our field trips and do the hard work. Working in remote regions, without the daily pleasantries of hot showers, air condition and high speed internet, and contributing financially to make those expeditions happen, these young adults are my heros. They might disappear back into a different world after the expedition, but they now understand what’s at stake.
  • We also work with Indigenous Land and Sea Ranger groups. With every group we have different agreements, and some are more hands-on in helping us than others. But all of them matter, and sawfish matter to them, as you can see in this blog post.
  • We also work with the public aquarium industry, who have sponsored some of our tags and are spreading the word for sawfish through their educational displays.

What about net free zones? Shall we close down all gill net fisheries? I personally think that net-free zones are only a solution in close vicinity of towns with large recreational fishing communities, and active fisheries enforcement. Closing down fisheries is not a solution, as it only exports the problem. Gill nets are used everywhere around the world, and in Australia we can document and invent methods of making these fisheries sustainable when it comes to sawfish by-catch.

In the remote areas that we work in, the displacement of fishers would mean that huge stretches of coastline will receive minimal attention in terms of patrolling and enforcement. The coastline of the Queensland Gulf of Carpentaria alone is about 1200 km long. This could create an open field for foreign fishing vessels, with no quotas or indications of catch and by-catch sizes or management strategies.

The area we work in covers about 2/3 the size of Germany, but it is only inhabited by 28,000 people. Germany, on the other hand, is inhabited by over 82 million people. In such remote areas, it is easy for foreign vessels to enter Australian waters undetected. Remember the vessel full of illegal immigrants that arrived in the Daintree, north of Cairns? This vessel crossed at least 800 km of Australian waters undetected before reaching the coastline.

The Australian fishermen and fisherwomen that I have met have an understanding of how their work changes the environment they work in. They are protective of their industry, that’s for sure, but they are also willing to adopt release practises that are safe and cause minimal harm to the animals. Many of them have developed great methods to release sawfish unharmed, and one of our ongoing projects is to document these methods, with the aim of making them available to every fisher. Without their help, the task of collecting data on Queensland’s sawfish populations is almost impossible. However, individuals who kill sawfish, like the recent deaths in Wujunga or this fisher, who was later found in possession of 63 illegal saws, can give a whole fishery a bad name.

My paper on the sawfish by-catches in the Queensland Shark Control Program indicates that sawfish survive the initial capture in a gill net. Anybody who has caught sawfish in this way, including myself, can confirm that as long as the animals’ gills are not wrapped up they can survive the capture. The key threatening process for sawfish is thus not the capture but the release. It is imperative for the survival of these species, that the animals are released alive, quickly and with minimal damage. Many fishers have adopted methods to avoid catching sawfish (like avoiding certain areas in the ecosystems they work in, or checking their nets very often), and many of them are aware of environmental conditions that will increase sawfish captures. These factors need to be documented in order to create best practise standards across fisheries. Ultimately, I would like to see a Sawfish Sustainability Certification for our Australian fisheries that interact with these animals, but this would require large-scale collaborations between governmental agencies, the conservation sector and fisheries.

Please think about how you fit into sawfish conservation and what you can do to protect these animals, instead of pointing the finger at other people. For example, if you live in an Australian city, you could become a sawfish ambassador and visit schools, hold outreach events and bring the memories of these animals back into people’s minds. This is hard work, but it is also more effective than signing a petition or liking a sawfish conservation post. You could also crochet us a sawfish to give to a remote school, or you could join us in the field. We need more sawfish heros.

International Sawfish Day in Cairns October 2019

International Sawfish Day in Cairns October 2019

International Sawfish Day in Cairns, October 2019

By Nikki Biskis

In October 2019, SARA and the Cairns Aquarium teamed up for an International Sawfish Day event in Cairns. Our sampling event was hosted by the Cairns Aquarium. The event notice was sent to 6,000 people and we were ecstatic with the response from the Cairns community. Former fishers and their families brought in specimens of all sizes and species to be DNA sampled, all with incredible stories to tell.

Barbara samples a saw at a local fishing store

This engagement with the community is crucial, as it helps SARA to understand genetic diversity amongst sawfish populations, and how the distribution of sawfish species have changed over time.

Barbara is interviewed by Win News!

What came next was even more exciting – many continued to submit information of their old saws to SARA and the aquarium, prompting another round of local visits across Cairns for samples. Our project is ongoing, and submissions are always appreciated!

As of today, Sharks and Rays Australia has received around 420 submissions, sampled over 200 saws including 140 that were received in donation. It is events and partnerships with the community that make this all possible.

Nikki sampels a saw at a local store

A special thank you to Cairns Aquarium and to everyone who made International Sawfish Day a success!

The cultural importance of sawfish in Australia

The cultural importance of sawfish in Australia

Once a year, the Cairns Indigenous Art Fair kicks off in Cairns. Indigenous artists from all over Far North Queensland and Cape York come to Cairns to display their arts. The event grows bigger every year and features so many works on sharks and rays that we always try to be in Cairns for CIAF.

This year, Julia, who is our instagram wizard, and myself visited CIAF together. We grabbed some food and sat down in the grass to listen to what was going on at the stage. Various Indigenous leaders from the Cape were talking about how their language and culture was slowly being lost. At some point, one of the elders started to talk about sawfish. He said that they had disappeared from his native waters and that he was from the community of Pormpuraaw. I looked at Julia and said, ‘We need to talk to him!’

After the session we introduced ourselves to Syd Bruce Shortjoe. I told him that we work with sawfish and that we would like to help him protect these animals in the waters of Pormpuraaw. I told him that SARA already works with the Mapoon Land and Sea Rangers as well as the Kowanyama Land and Sea Rangers. As I had heard of recent captures of sawfish from the Pormpuraaw region, I said to him that sawfish still exist in his native waters, but probably in very low numbers. I also gave Syd one of our flyers and a sunnies neoprene strap that has all the information on how people can submit sawfish sightings to us. While Syd was listening, he started stroking the sawfish image on the neoprene strap.

Syd told us that his great grandfathers’ totem is the sawfish. He said that because of this, the sawfish is part of his family and his culture. If the animals go extinct, then not only is the species missing from local ecosystems, but it also means that the totem goes extinct. In his cultural belief, you become your totem animal after your death. His grandfather’s totem is the green sawfish, and Syd described the animals very accurately. In Mugu, the sawfish is called kapainyinh.

Syd is the first person who I have met who had a sawfish totem in his family.

He looked at me and grabbed my arm. He said ‘Sawfish cannot disappear. This means my family’s totem disappears and my culture disappears. And with your help we can stop that.’ I grabbed hold of his arm and said to him that I will help him and I will try my best to teach his community, his people, the school kids and the rangers so that we can all come together to look after sawfish and bring these animals back to his waters.

This moment was highly emotional for Julia and myself. While we often meet people who are very interested in sawfish, and while we both understood the cultural importance of sawfish to Indigenous Australians, we were completely unaware of the cultural impacts of the species’ declines.

When Syd looked at me and asked me for my help I realized that there is too much at stake. We need to look after sawfish and we need to do this together.

At the Cairns Indigenous Art Fair. From left to right Barbara Wueringer (SARA), Eliot Koonutta (Pormpuraaw artist), Julia Constance (SARA) and Syd Bruce Shortjoe (Pormpuraaw Elder)

This blog post was written for the Save Our Seas Foundation. Access the original here.

 

The species we work with

Thanks to Garry Ogston, Gemma Bauld and Grace McNicholas and Morna McGuire for writing the summaries!

Freshwater (or largetooth) sawfish Pristis pristis

by Gary Ogston

The largetooth sawfish (Pristis pristis) can be found across the globe, and consists of four separate sub populations; the Western Atlantic, Eastern Atlantic, Eastern Pacific, and Indo-West Pacific (including northern Australia – spanning the Kimberley to Cape York Peninsula). The species was once considered common across many of these sub populations but has unfortunately undergone drastic population reductions. The largetooth sawfishis now thought to be locally extinct in many regions, and as such is listed as Critically Endangered under the IUCN Red List. The Kimberley region in north-western Australia represents one of the last intact nurseries for the largetooth sawfish, however even within Australia the species is threatened and listed as Vulnerable under Australia’s EPBC Act.

The species is biologically fascinating, both in appearance, due to its large rostrum (averaging between 17 and 24 teeth per side) which is used for predation and defence, and also in its ability to tolerate a wide range of salinities (euryhaline). The largetooth sawfish will spend the first three to four years of its life within freshwater systems growing to a length of approximately 3-4m, before then migrating into the estuarine and marine environments where they reach over 6m in length as an adult. Within the freshwater systems, the diet of the largetooth sawfish consists primarily of species found in the lower water column or benthic environment, such as the blue-catfish (Neoarius graeffei), and detritus.

Fun Facts!

  • Did you know? Largetooth sawfish are ovoviviparous; meaning the young develop inside an egg case but remain within the body of the mother until they are ready to hatch, before then being born as live young!
  • Did you know? Unlike bony fish, sawfish have no swim bladders and instead rely on large oil-filled livers to help with buoyancy!

Dwarf sawfish Pristis clavata

by Gemma Bauld

The Dwarf sawfish (Pristis clavata) is a species of sawfish that can reach at least 318cm in length. It is greenish-brown above and white underneath with gill opening on its underside. Like other sawfish species it has a toothed rostrum. The Dwarf sawfish is found within sand and mud flats associated with close proximity to mangroves in shallow coastal and estuarine waters of northern Australia in the Northern Territory, Queensland and Western Australia. Dwarf sawfish are viviparous (giving birth to live young), with litter sizes unknown but are assumed to be similar to other Pristisspecies with an average of approximately seven pups per litter. Juveniles are estimated to be between 60‑81cm at the time of birth, and males of the species reaching maturity at eight years old, being approximately 255‑260cm. It is estimated that the Dwarf sawfish have longevity of up to 34 years. Dwarf sawfish in Western Australian waters have been found to occupy restricted areas of habitat. They move up to 10km during each tide cycle, staying within inundated mangrove forests during high tide and moving out a few kilometres on the low tide. Individuals were found to return to within 100m of their previous high tide resting sites demonstrating repeated use of habitat. They frequently occupy habitats less than 2m deep. Current major threats to the Dwarf sawfish include getting their toothed rostrums stuck in fishing nets in shallow waters in which they inhabit. Historically their rostrums were also collected and traded. However, from 2009, this species was protected from all commercial and recreational use and trade in Australia. The Dwarf sawfish is currently listed as endangered on the IUCN Red List.

References:

The IUCN Red List of Threatened Species

Fishes of Australia

Green sawfish Pristis zijsron

by Gemma Bauld

The Green sawfish (Pristis zijsron) is a species that can grow to between five and seven metres in length and is possibly one of the largest sawfish. They are greenish-brown or olive above and pale to white underneath, with gill openings on its underside. Like other sawfish species it has a flattened head and an elongated snout with uneven-spaced teeth along each side. This is commonly called the rostrum. The Green sawfish in Australia used to be found as far south as Sydney, however its range is now limited to northern Australia (Queensland, Northern Territory and Western Australia). The Green sawfish is also found in the Indo-West Pacific from southern Africa to the Red Sea, Persian Gulf, southern Asia, Indo-Australian archipelago, east Asia and as far north as Taiwan and southern China. They generally inhabit shallow water in coastal and estuarine areas in close proximity to mangrove shorelines. Green sawfish are viviparous (giving birth to live young), with litters being approximately 12 pups. Juveniles are estimated to be approximately 76 cm at the time of birth, and reaching 340–380 cm at maturity at nine years of age. A maximum age for this species is greater than 50 years. Current major threats to the Green sawfish include getting their toothed rostrums stuck in fishing nets in shallow waters in which they inhabit. Historically their rostrums, fins and meat were also collected and traded locally and internationally, however, this species is now protected from all commercial and recreational use and trade, although difficult to enforce in some countries. The Green sawfish is currently listed as critically endangered on the IUCN Red List.

References:

Simpfendorfer, C. 2013. Pristis zijsron. The IUCN Red List of Threatened Species 2013: e.T39393A18620401. link

Department of the Environment (2017) Pristis zijsronin Species Profile and Threats Database, Department of the Environment, Canberra. link 

Narrow sawfish Anoxypristis cuspidata

(pending)

Freshwater whipray Urogymnus dalyensis

by Morna McGuire

The freshwater whipray,is the only species of Australian stingray to live exclusively in fresh and estuarine waters. It was first discovered in the Daly River, Northern Territory, giving rise to its epithet: dalyensis. Since then, freshwater whiprays have been documented in at least 10 northern Australian rivers, suggesting they are endemic to the region. As bottom-dwelling species, feeding on small fish and shrimps, they are usually distributed at depths of 1 – 4 m.

What do they look like?

The main body (pectoral fin disc) of freshwater whipray is distinctively apple-shaped, being as wide as it is long. Projecting from this disc is an obtuse snout, which tapers to a pointed tip. The colouration of its dorsal surface is grey-brownish, though darkens towards the tail. Contrastingly, its ventral colouration is banded: brown spots separate the white centre from the brown margins. Its tail is whip-like (long and thin), often measuring double the disc length. The tail bares a single serrated venomous spine, likely used for defence.

Freshwater whiprays are easily confused with two other ray species: giant freshwater stingray (Himantura chaophyraya) of South-East Asia and estuary stingray (Dasyatis fluviorum) of eastern Australia. However, both molecular and morphological comparisons confirm that they are separate species. For example, the tail of freshwater whipray lacks the ventral skin-fold typical of other ray species.

Although freshwater whiprays are regarded of Least Concern (IUCN Red List), very little is actually known about their ecology. How large is the population?At what age are they sexually mature? SARA’s research on this species is therefore integral to its survival, by informing fishing management practices and conservation efforts.

Fun fact!

Freshwater whiprays are fully committed to catching their prey; they may charge up riverbanks so fast that they breach themselves!

References:

Last, P. R., Stevens, J. D. (2009). Sharks and Rays of Australia. Edition 2. CSIRO Publishing.

Last, P. R., & Manjaji-Matsumoto, B. M. (2008). ‘Himantura dalyensissp. nov., a new estuarine whipray (Myliobatoidei: Dasyatidae) from northern Australia’. Descriptions of new Australian Chondrichthyans. CSIRO Marine and Atmospheric Research, 22, 283-291.

Bull shark Carcharinus leucas

by Garry Ogston

The bullshark (Carcharhinus leucas) is found in warm temperate and tropical waters around the globe, including countries such as Australia, India, Ecuador and the United States of America. The species is listed as Near-Threatened under the IUCN Red List and faces several threats including recreational and commercial fisheries with commercial fisheries globally being driven by the demand for shark fins, liver oil and meat, however it is also regularly caught as by-catch. The species is also threatened by habitat modification, particularly of nursery grounds e.g. estuarine and freshwater systems. Within Australia the bullshark is not protected and is able to be caught for both recreational and commercial fisheries. Several regions of Australia however, have imposed size limits to reduce the threat of overfishing mature specimens.

Although common in marine and estuarine waters, it is only one of a few species of shark that can tolerate long periods in freshwater (e.g. also see river sharks Glyphis spp.), allowing it to penetrate large distances upstream. Pregnant females migrate to the estuarine, freshwater regions to give birth, with the juveniles utilising these areas as nursery grounds. When born, the bull sharks measure between 0.5m and 0.8m, before maturing at approximately 1.5-2.2m for males and 1.8-2.3m for females. A full grown adult bull shark can reach over 3m in length. As the bull shark matures it also diversifies its diet, consuming a range of prey species from turtles to birds, teleost fishes and elasmobranchs, and even crustaceans.

Fun Facts!

  • Did you know? Bull sharks possess organs known as the ampullae of Lorenzini which act as electroreceptors. These organs are “jelly” filled pores that help detect electrical fields within the water
  • Did you know? Bull sharks are not always at the top of the food chain and get predated on by other bull sharks, Orca’s, and even crocodiles!

Winghead shark Eusphyrna blochii

by Grace McNicholas

The Winghead Shark (Eusphyra blochii) is found around the Indo-West Pacific continental shelf. Found in shallow coastal waters, wingheads feed on/near the bottom, with a diet consisting of crustaceans, cephalopods and small fish. Growing to a maximum total length of just 186 cm, they are smallest of all hammerhead species. Being the smallest species, their characteristic elongated head or ‘cephalofoil’ also has the highest width to body length ratio of all hammerheads. It can reach nearly 50% of their total body length. Males and females reach maturity at around 108 cm and 120 cm respectively, and both sexes have a distinct seasonal reproductive cycle, breeding once a year. Females give birth to live young in February/March in litters of 6 – 25 pups, with new-borns measuring approximately 45 cm.

Unfortunately, winghead sharks are impacted by coastal gillnet fisheries, as their slender elongated heads are easily caught in a range of gillnet mesh sizes. They have also been heavily exploited for their fins and meat. Over the last three generations it is estimated the global population has declined by at least 50%. These declines are most pronounced in areas with intense coastal fishing such as Indonesia and other Asian countries, where reports of wingheads in landing surveys have become less and less common. As a result, Eusphyra blochii are now listed as globally Endangered on the IUCN Red List. However, in Australia, winghead populations are still thought to be relatively healthy due to much lower bycatch levels in the better managed Australian gillnet and trawl fisheries. Although the Australian population is currently only listed as Least Concern, they may still be at risk due to their patchy distribution.

References:

Chin, A, et al. (2017). Crossing lines: a multidisciplinary framework for assessing connectivity of hammerhead sharks across jurisdictional boundaries. Nature Publishing Group, (April), Nature Publishing Group., pp.1–14. [Online] Available at: doi:10.1038/srep46061.

Compagno, LJ. (1984). FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. FAO Fisheries Synopsis No. 125, Volume 4, Part 1.

Sainsbury, KJ, Kailola, PJ, and Leyland, GG. (1984). Continental Shelf Fishes of Northern and North-western Australia, an Illustrated Guide. (Clouston and Hall: Canberra.)

Smart, JJ.and Simpfendorfer, CA. (2016). Eusphyra blochii. The IUCN Red List of Threatened Species. [Online]. Available at: doi:org/10.2305/IUCN.UK.2016- 1.RLTS.T41810A68623209.en.

Stevens, JD and Lyle, JM. (1989). Biology of three hammerhead sharks (Eusphyra blochii, Sphyrna mokarran and S. lewini) from Northern Australia. Marine and Freshwater Research, 40, pp.129–146. [Online]. Available at: doi:10.1071/MF9890129.