Assessment of the abundance and distribution of four species of sawfish
In 2015, Sharks And Rays Australia started an assessment of the current distributions and abundance patterns of four species of sawfishes in Far North Queensland and the Cape York Peninsula.
Sawfishes are the most endangered rays in the world. For example, the freshwater (or largetooth) sawfish Pristis pristis, which we work with, is considered to be amongst the 100 most threatened species in the world.
Northern Australia is the last global stronghold for four species of sawfish. Within this region, the coastline and in the river system of the Cape York Peninsula are most likely to still hold the highest densities of sawfishes.
The last assessment of the distribution and abundance of the four species of sawfish occurring in Queensland’s waters ended in 2008. Since then, sawfish have been declared a no-take species in Queensland’s waters, but it is unclear if this measure is effective.
The ’Vulnerability assessment for the Great Barrier Reef, sawfish’ indicates that:
- “More fishery independent data of sawfish distribution in Far North Queensland is needed, as the data collected to date can only be considered preliminary.
- “There is a paucity of information on the biology and ecology of sawfish in the World Heritage Area and on what is required to maintain their habitats and populations.
- “These concerns present difficulties for informed management of sawfish in the GBR.
Trophic position and ecological roles of euryhaline elasmobranch predators
The key objective of this project is to elucidate the trophic positions and ecological roles of six species of estuarine and euryhaline elasmobranchs within their coastal and riverine habitats on the Cape York Peninsula in Australia. We will involve the public in data collection and thus educate them about these animals and ecosystems.
Why is this important
Globally populations of aquatic apex and mesopredators, including elasmobranchs, are declining at alarming rates. This loss of predators and their regulatory effect on lower trophic species can change ecosystems. Therefore, the assessment of elasmobranch community structures is highly important for the creation of management plans.
The remote habitats of Northern Australia and the Gulf of Carpentaria are home to very rare, globally threatened and little-understood elasmobranchs. Here, the last global stronghold remains for four species of sawfish – the most threatened elasmobranch family. Other endemic and threatened megafauna are speartooth sharks and freshwater whiprays, which were only described in 2008.
Because of its low human population density, Cape York is relative pristine. But as development in these ecosystems progresses, the area might soon be threatened.
This project’s multi-disciplinary scientific approach will allow collection of baseline data on the biology of the study species in a relatively pristine environment. This information is needed to understand the species’ conservation requirements in Cape York and elsewhere around the globe. Meanwhile, the public outreach component of the project aims to put sawfishes on the international eco-tourism map as flagship species in Cape York. This approach will allow us to develop long-term monitoring programmes for these species and also make their existence in Australia common knowledge.
Euryhaline elasmobranchs (that is, elasmobranchs able to adapt to a wide range of salinities) and freshwater elasmobranchs, including the six study species, are particularly vulnerable to habitat modification and destruction, pollution and overfishing because of their restricted habitat and large body sizes. To achieve tailored protection measures, we need to fill the gaps in our knowledge of the biology and community structures of the six study species. This project aims to provide a holistic understanding of the species’ biology through a multi-disciplinary approach. So far, my line of research has focused on the sensory biology and feeding behaviour of these six species, uncovering many of their adaptations, which define their theoretically optimal niche. The proposed project is an expansion of this work to identify where these species fit in food webs and how they use their microhabitats. This will enable us to identify potential impacts of anthropogenic modifications (e.g., sedimentation changes and salinity changes).
Aims & objectives
The aims and objectives of this project are to:
- Assess the ecological niches and microhabitats of the study species. Microhabitats will be identified through analysis of spatial habitat use, activity patterns, predatory behaviour and the species’ relationship with abiotic and biotic habitat factors (e.g., visibility, water temperature, depth, salinity, prey abundance).
- Assess the trophic levels and isotopic niche spaces of the study species within their habitats and in relation to each other and other species. Given their sizes, all could be apex or mesopredators.
- Identify differences and similarities in sensory and neurological adaptations between the study species. Knowledge of these adaptations will shed light on the ‘theoretically optimal niche’ of these species.
This research is part of a larger project that is on-going. Overall it aims to:
- Collect data on the spatial ecology of adult sawfish in North Queensland. Animals will be satellite tagged after they have given birth in estuaries and before they move into the Gulf of Carpentaria. This is vital, as to date virtually nothing is known about sawfish once they become sexually mature
- Involve local schools, the local community, tourism operators and tourists in the proposed research.
Both projects are currently receiving funding from the Save Our Seas Foundation.
Working with wild animals is a privilege that comes with the responsibility of taking care of these animals.
At SARA we are committed to the welfare of everybody involved in our research – including that of animals. All our staff, volunteers and participants are trained to handle animals safely. Our animal capture, handling and release methods are regularly reviewed as part of our Safe Work Procedures.
SARA is registered with Biosecurity Queensland as a user of animals for scientific research. Our research procedures ensure the reduction of stress to the animals during capture, handling and release, under the Australian Code of Practise for the Care and Use of Animals for Scientific Purposes. Before research commences, our research procedures are approved by an Animal Ethic Committee, which also monitors the progress of research projects.
A pump is inserted into the mouth of a juvenile bull shark, to both flush its gills during the work up and also occupy its mouth.
As SARA is expanding, we have identified various projects that we would like to pursue together with students. This page serves to provide you with ideas but projects are not limited to what is listed here. Our fieldwork in remote regions of Queensland is very rewarding but also physically demanding. It is important that we work well together and therefore we require all prospective students who want to do a project involving fieldwork to join us for an expedition prior to commencement. This will allow you to understand our work better and allow us to assess your fieldwork skills, people skills etc. so that we can work out a strategy for your project.
As SARA is not a post-graduate research provider, you will need a primary project supervisor based at a university, which could include our collaborators. Dr Wueringer will be your co-supervisor. SARA will provide you with a platform to do your research. As mentioned throughout this page, our field sites are remote and off the beaten track. In order to conduct research in such areas you need a team that plays well together and the necessary infrastructure to conduct the project.
If you want to be involved in any of our projects, we propose the following steps:
- Read through the listed projects and think about them. Do you have skills or interests that match a project?
- Think about the project duration, are you aiming for a one-year honours project or a three-year PhD project?
- Which university would you like to work with? Can you think of supervisors?
- Please also consider visa issues. If you join us form an international uni then see internship section below.
- Can you think of funding that you could apply for?
- You do not need to have answers to all these questions when you get in touch with Dr Wueringer to discuss projects.
GIS desktop assessment of sawfish habitat
There are four species of sawfish found in Queensland waters, each with different habitat requirements and ecologies. The known distributions of these four species are quite broad and/or disjoint, and especially on the east coast of Queensland it is unclear if this reflects incomplete sampling or distinctive populations.
- Desktop study & literature review: identify factors that could affect the distribution of each species and review current knowledge of distribution patterns for four species of sawfish in Queensland’s waters.
- GIS study: identify potentially important habitat for sawfishes within our Queensland study region, for example by expanding the River Disturbance Index.
- Combine these data with sawfish sightings and model and identify key habitat for sawfish under future climate change scenarios.
The trophic position and isotopic niche space of sawfishes and other elasmobranchs in riverine communities in tropical Queensland
In 2016 we commenced collecting stable isotope samples of food webs that include elasmobranchs, in a variety of habitats. The aim of this study is to compare the food webs in different river systems that lead into the Gulf of Carpentaria. Each river is quite different, not only in the microhabitat it provides but also in the surrounding terrestrial vegetation. Different approaches could be taken, and the collected data is available to more than one student project!
- Objective 1: Compare a river with high sawfish abundance with a river where sawfish are not present (anymore).
- Objective 2: Identify the effects of anthropomorphic degradation of adjacent terrestrial ecosystems (e.g. cattle farming on flood plains, effects of invasive species) on the riverine food webs in a comparative study.
- Some of our stable isotope samples have now been analysed, while others still need to go through the preparation.
- Our data now includes 28 different species of elasmobranch, which could be analysed separately!
Distribution and occurrences of Arid catfish in Far North Queensland
Our fieldwork data includes a large amount of information on catches for arid forktail catfish. Many recreational fishers do not like catfish, which likely comes from the idea that there are only 1 or 2 species present in large numbers in Far North Queensland’s waters. In reality, there are 18 species present. Their distribution patterns, and standardised catch rates can be assessed form our data. These patterns likely represent habitat specialisations, that could help us predict microhabitats in our sample locations. We also have stable isotope samples for catfish!
Distribution patterns of sawfish in Queensland waters
Our sawfish tagging study is ongoing but needs one or two dedicated students to expand it.
- Expand the ongoing fieldwork component. You need to have extensive fieldwork experience in order to apply for this!
- Increase stakeholder involvement (commercial and recreational fishermen and Fisheries Queensland) in collecting sightings information for this project.
- Collate information of sawfish captures in Queensland, historic and recent through press releases and working with recreational fishing clubs – project is ongoing.
Fine tuning of sampling methods for sawfishes
Historically, sawfish are best caught with gill nets compared to lines with hooks (Wueringer, 2017). Their saw easily entangles in the monofilament mesh of gill nets, and healthy juvenile sawfish do not often take dead bait. However, sampling with gill nets is a labour intensive, time-consuming method that is also not preferred in the GBRMPA region. Gill nets catch fish by the gills and can quickly kill animals, especially if they require to move in order to ventilate their gills, like sharks. Because of this nets have to be checked regularly (at 15-30 mins intervals). Gillnets can also get entangled in submerged structures and collect debris which creates visual barriers that larger animals will avoid.
Because of this, we want to develop more effective and targeted methods to capture sawfish. These methods could allow us to sample more areas over the course of a sampling session, with the reduction of labour and by-catch.
Fine tuning of release methods for sawfishes
We have just commenced a project that aims to involve commercial fishermen in our sampling study for sawfishes.
- Develop a device that makes it easier, faster and safer to release sawfish from gill nets. This device is already being used by some commercial fishermen, but needs to be tested, improved and modified for sawfish of different sizes and species.
- This project can easily be completed within a few months in Cairns, and and requires a person with an engineering and creative mindset to implement it.
- Creation of a best practise release manual for sawfish. The manual currently used by many fishermen is a decade old and for example does not provide information on tonic immobility.
Students will also be involved in our ongoing projects:
- Assessment of the abundance and distribution of sawfishes in Qld waters (see above).
- Collection of genetic samples of all elasmobranchs captured tagged and released from our survey equipment.
- Public awareness campaign for sawfishes, their conservation status and their ecology. We work with Indigenous Ranger groups in the field and also give presentations in local schools during sampling expeditions. We also distribute sawfish ID flyers in the region, and our fieldwork would not be possible without volunteer field assistants. We hope that sawfish will become a flagship species for the region!
- Habitat assessment of rivers and coastal regions in the study region.
- eDNA sampling (Commenced in 2018 in collaboration with JCU)
- Detailed terrestrial and aquatic habitat assessment (to commence in 2019). We are already collecting information on the physical parameters of the aquatic habitats that we sample, but we will expand this through the projects mentioned above and in collaboration with Mangrove Watch. We aim to assess the type (mangrove forest, flood plain, grass land) and state (modified by cattle, natural, close to road) of terrestrial habitat surrounding sampling sites.
- Social media outreach. We want to expand this!
SARA accepts interns who would like to gain work experience and students who would like to do a short project for a degree at an Australian or international university.
As an intern you will:
- Need to support yourself financially. Internships at SARA are unpaid. They are also free of cost!
- Need to consider fieldwork fees if you intend to join expeditions.
- Contribute to the ongoing administrative work at SARA for min. 5 hrs per week. This includes but is not limited to: Outreach activities, blog post writing, social media, data entry, research equipment and gear preparation and repairs.
- Contribute to one of our ongoing long-term or student projects.
In order to start the conversation regarding an internship please email barbara(at)saw.fish with:
- A cover letter that includes details on which research you would like to conduct in regards to SARA’s projects and how your skills and knowledge can contribute to this project
- your CV
- Your availability / time frame.
Please be advised that while SARA has a work shed for our gear and hands-on work, we do not waste money on office space. Thus office work and data analysis can be done from anywhere 🙂
In order to come to Australia as an international intern you can be on a ‘Work & Travel visa’ or a 407 training visa. The requirements of the 407 visa include but are not limited to: English test, proof of employment or uni enrolment for 12 out of last 24 months, health requirements, character requirements. You can find information on these requirements through a web search. The visa can take up to 2 months to process, so plan ahead.
WE WORK IN AREAS WITH LARGE NUMBERS OF SALTWATER CROCODILES, SO WE DO NOT GO SHARK DIVING.