Non-destructive sampling methods are needed to provide quantitative data on the population status of pelagic sharks and fishes, particularly in marine reserves and other areas where fisheries catch data are unavailable.
This project developed non-destructive techniques for monitoring pelagic sharks and fishes. It contributed to the development of baselines for pelagic shark and fish assemblages in Commonwealth Marine Reserves (CMRs), as well as in other areas of interest to the international community. Mid-water camera systems developed in this project have been used during pelagic expeditions supported by the National Geographic Pristine Seas initiative (see story Exploring pristine seas).
Approach
Approaches to sampling pelagic shark and fish assemblages were reviewed and non-destructive mid-water stereo video camera systems for collecting quantitative data were developed and tested. NERP Marine Biodiversity Hub field surveys conducted to establish pelagic baselines in new CMRs (Oceanic Shoals CMR and Perth Canyon CMR) provided ideal testing grounds.
The mid-water camera rigs consist of a supported, horizontal bar on which two cameras are mounted in fixed housings. A system of floats maintains buoyancy and stability and a bait canister is held by a horizontal arm.
Video imagery is analysed using custom software to determine species richness and abundance, as well as the length of individual animals. These data are used for monitoring changes in the diversity, abundance and size structure of pelagic shark and fish assemblages.
The success of the new systems led to further involvement in international surveys for pelagic sharks and fishes and other wildlife. In 2012–2014, expeditions were made to Chagos Archipelago, New Caledonia, Palau, Tonga, and Rapa/Marotiri, and Gambier islands in French Polynesia, with support from international partners.
Key findings
Mid-water stereo video camera systems can effectively quantify characteristics of pelagic shark and fish assemblages such as species diversity, abundance and size structure. As a non-destructive technique, the method is appropriate for monitoring marine protected areas.
Mid-water stereo video camera systems are a cost-effective, highly versatile technique that can be deployed from a variety of platforms (small tenders to large oceanographic vessels), in varying configurations (moored, drifting), and combined with complementary techniques such as acoustics, depending on monitoring requirements.
Estimates of species richness and abundance generated by mid-water stereo video camera systems support the design of MPAs by identifying pelagic hotspots. The estimates also contribute to establishing baselines for MPA monitoring and other applications such as environmental impact assessments.
Pelagic assemblages, as unveiled by mid-water stereo video camera systems, are diverse, and include a wide range of animals from juvenile reef fishes in their pre-recruitment phase to large marine animals such as tunas, oceanic sharks, and orcas.
New knowledge and opportunities
Mid-water stereo video camera systems can be used to collect baseline data on pelagic species that can contribute to assessing the effectiveness of Australia’s CMR network and international MPAs. The expanding use of mid-water stereo video camera systems will enable the status of Australia’s pelagic assemblages to be evaluated in an international context.
Outputs and outcomes
This project developed new techniques to estimate the abundance and species richness of pelagic fish in marine reserves. This information may be useful in assessing performance of CMRs. Stereo video camera systems have collected pelagic fish and shark imagery and data at:
- Shark Bay, WA;
- Perth Canyon CMR, WA;
- Oceanic Shoals CMR, Timor Sea;
- Chagos Archipelago, central Indian Ocean;
- Palau, western Pacific;
- New Caledonia, western Pacific;
- Rapa/Marotiri, western Pacific;
- French Polynesia, central Pacific; and
- Tonga, central Pacific.
A compilation of high-quality video footage from the Perth Canyon CMR is available online, supported by a grant from the Australian Academy of Science through its Margaret Middleton Fund Award for field-based ecological research on endangered Australian vertebrates.
Contact
Jessica Meeuwig
jessica.meeuwig@uwa.edu.au
0400 024 999