A baited remote underwater videos station (BRUVS) is lowered into the water by AIMS scientists. Photo: Matt Birt
Video and image-based monitoring in marine environments provide excellent opportunities to conduct research in places difficult for humans to access. Video offers many advantages over traditional diver-based monitoring such as:
- observing life in parts of the ocean out of reach of divers
- reducing observer bias
- sampling in sensitive areas without impact (because they are a ‘no-take’ tool and are harmless to fish and habitat)
- creating a permanent record of observations for future reference and quality assurance
- allowing easy exchange of information between researchers and other stakeholders
- reducing in-water time for divers, lowering personal risk and increasing the number of sampling hours
- potential to use imagery as the basis for artificial intelligence and automated data collection
Our teams use a variety of image based monitoring techniques in tropical marine waters, including baited remote underwater video stations (BRUVS) and towed video.
Baited remote underwater video stations (BRUVS)
First pioneered by AIMS and collaborators, baited remote underwater video stations (BRUVS) are a common fish-surveying tool around the world. These stationary, seafloor camera stations use bait to attract fish in their vicinity, recording the species attracted to the bait or swimming past the camera lens.
BRUVS are excellent for observing fish in hard-to-reach habitats in both shallow and deep waters, such as reefs and shoals, areas between reefs and continental shelves.
A stereo BRUVS (with two cameras) sits amongst a rich coral reef habitat at Rowley Shoals, Western Australia. Photo: Matt Birt
Simple but effective marine life monitoring
At the heart of a BRUVS is a small, inexpensive action camera in a simple but robust underwater housing. This camera is held in a steel frame that also holds a bait arm. At the end of this bait arm is with a mesh bag full of minced pilchards to attract sea life. Lights can be added for night and deep water surveys.
BRUVS are often deployed in fleets of eight or more at a time across a large area by either a large research vessel or smaller tenders. Each station is attached to a rope and surface marker float that allows it to be retrieved after filming.
The footage is analysed back in the laboratory where fish are identified by specialists and their relative abundance recorded.
The Global FinPrint project used lightweight transportable BRUVS to survey sharks and rays in remote locations worldwide. Photo: Steve Lindfield CRRF (Coral Reef Research Foundation Palau)
As well as the benefits of video camera sampling mentioned above, BRUVS let us:
- make precise length and biomass estimates with analysis of paired images when cameras are used in stereo-pairs,
- capture detailed images of habitat types, which can be incorporated into the analysis,
- record large, mobile animals, such as sharks, rays and sea snakes that normally avoid scuba divers or towed video cameras.
BRUVS provide information on the number of species and individuals, community structure, and fish sizes throughout the world. They allow us to compare trends before and after industry activity or disturbance events, through different seasons and between years.
An important tool in our monitoring toolkit
BRUVS are used in a number of projects throughout AIMS including:
- monitoring and documenting biodiversity at iconic reefs and shoals in Australia’s North West such as Rowley Shoals, Scott Reef and Ningaloo Reef
- monitoring effects of marine noise on fish populations; and documenting patterns of fish biodiversity as part of the North West Shoals to Shore Research Program
- Monitoring the effects of bleaching and other impacts upon the Great Barrier Reef
- A global survey of shark and ray diversity for the Global FinPrint project
Towed video cameras help survey large areas of ocean floor down to 300m in a systematic way.
A video camera (equipped with other sensors to aid positioning and data collection) is towed behind a boat at a fixed speed along a survey line, also known as a transect. At the same time, scientists observe the seabed habitat through a video link to the camera and take high-resolution photos at regular intervals.
The video and photos are later analysed to describe habitats, determine species distributions, and map seabed biodiversity over broad areas.
A towed video body waiting to be deployed from the back of a research vessel. Photo: Marcus Stowar
Discovering habitats in unexplored places
We use towed video extensively in the north-west of Australia as part of our commitment to the sustainable ecological development of marine resources. This tool helps us discover the types of habitats that occur in remote and previously unexplored locations - from the inshore Kimberley coast to deep, offshore shoals far to the north and north-west of mainland Australia.