Open Ocean Monitoring in the Chagos Archipelago
The designation of the Chagos Marine Reserve, and subsequent closure of the pelagic fisheries, in 2010 represented a significant step in the conservation of pelagic predators such as tuna and sharks. Many of these species are internationally threatened and large no-take MPAs like Chagos have been proposed as offer unique refuges from exploitation. Whilst the benefits of no-take MPAs have been demonstrated in coastal areas, their efficacy in the pelagic environment is less well understood. Here at ZSL, we are trying to understand how pelagic predators such as tuna and sharks use the MPA and also learn more about their population status and biology.
Pelagic environments are often remote making it hard to deploy human teams or short-term monitoring equipment. The species themselves can pose problems for monitoring as their roaming behaviour and patchy distribution create a ‘needle-in-a-haystack’ scenario for scientists.
ZSL’s Marine and Freshwater team, in collaboration with University College London (UCL) and the University of Western Australia (UWA), are attempting to tackle some of these problems by developing and adapting novel and existing technologies to better apply them to the pelagic environment through our Open Ocean Monitoring project.
Six project areas exist to tackle different elements of our knowledge and technology gaps with non-destructive methods:
1. Identify key aggregation sites for monitoring on-going monitoring
2. Development of benthic and pelagic video monitoring
3. Use of satellite telemetry through shark tagging
4. Utilising acoustic technology to track fish biomass
5. Identifying and mapping oceanographic factors that affect shark and tuna behaviour
6. Harnessing these new and exciting technologies to engage the public
Progress so far:
David Curnick, a joint researcher between ZSL and UCL, is currently investigating the efficacy of large MPAs for pelagic predators. His research focuses on analysing existing fisheries data and satellite tagging individuals to understand spatial, temporal and demographic distributions, movement between populations, habitat utilisation and site fidelity of focal species within, and adjacent to, the MPA. For more information on David’s research, click here
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Video-based surveys using Baited Underwater Video Systems (BRUVS) during the autumn 2012 Chagos expedition saw more than 150 seabed areas filmed as a baseline assessment – see some of the footage below.
Parallel to this success, ZSL and partners are developing and trialing pelagic monitoring systems for similar analysis – Stereo Imaging System for Shark and Tuna Assessment SISSTAS). These were trialed for short term deployments in Australia with project partners at the University of Western Australia. Since those preliminary trials the team have been adapting the units for long-term deployments, the first generation of which were subsequently trialed by Gary Fletcher during the recent spring 2013 Chagos expedition. Pelagic cameras were hosted below strategically located buoys, with a view to future deployments of arrays, thus enabling researchers to quantify the status and trends in pelagic fish communities within the MPA.
The incorporation of satellite transmission capabilities aims to make these cameras suitable for fully remote deployment. It is also hoped that these units will feed into the existing {error} giving users the chance to explore the underwater environment on their tablet or smartphone.
View some of the footage highlights from these trials below.
