T-POD description

Since its incorporation in 2004, Ocean Science Consulting Ltd (OSC) has been using the T-POD to acoustically monitor marine mammal activity around oil & gas rigs and production platforms. The T-POD detects bio-sonar (echolocation) click trains of odontocetes (toothed whales, dolphins and porpoises), providing temporal (time) data on animal activity, as an indication of presence or habitat usage. Other behaviours such as feeding activity can also be inferred, but such interpretation involves considerably greater and more highly specialised data analyses, which OSC can also provide. These Passive Acoustic Monitoring (PAM) devices are relatively low-cost, fully automated (battery powered), and static (i.e. surface or sub-surface moored), so they provide a cost effective method for gathering large datasets over long periods with minimal field-effort. Apart from the more recently developed C-POD, the T-POD is the only other commercially available system that uses click train detection for odontocetes. The T-POD has now been superseded by the C-POD, but the T-POD is still very much the tried and tested technology with an excellent track record, and continues to deliver the best results under certain conditions.

The T-POD (and C-POD) comprise an omni-directional hydrophone, an analogue processor, a digital timing/logging system and analysis software. The T-POD (and C-POD) log frequency, duration and bandwidth of each click with a target range of 9 kHz to 170 kHz, and the operator is able to set various acoustic criteria to help target specific species. The T-POD (and C-POD) also log temperature and attitude (and the C-POD further logs intensity of clicks, which is intended to assess the effects of ambient noise). The associated analysis software automatically detects odontocete click trains while filtering out non-odontocete clicks such as vessel sonar. The T-POD (and C-POD) are capable of detecting harbour porpoises (Phocoena phocoena) up to a range of approximately 300 m, and close to 100% detection reliability can be attained within approximately 70 to 100 m. Compared to harbour porpoises, the majority of odontocete species vocalise at relatively lower frequencies and consequently can be detected at considerably greater distances e.g. bottlenose dolphins (Tursiops truncatus) at approximately 1500 m. Deep-water versions of the T-POD and C-POD are also available for monitoring species such as pilot whales, beaked whales, and sperm whales.

Left-hand side: Dr Victoria Todd resting with a T-POD (blue) and C-POD (grey) – OSC scientists are very attached to their PODs! Right-hand side: an example of our serious mooring techniques. © OSC 2012.

Left-hand side: Dr Victoria Todd resting with a T-POD (blue) and C-POD (grey) – OSC scientists are very attached to their PODs! Right-hand side: an example of our serious mooring techniques. © OSC 2012.

Usually, marine scientists deploy many T-PODs (and/or C-PODs) simultaneously and anticipate losing a high percentage; however, Ocean Science Consulting has developed several unique deployment and mooring methods that have resulted in a 100% recovery rate of our T-PODs to date i.e. none lost.

T-POD application

The T-POD (and C-POD) is ideally designed for monitoring odontocete activity over periods of days, weeks, months, or even years. This Passive Acoustic Monitoring (PAM) tool is optimised for conducting Environmental Impact Assessments (EIAs), investigating odontocete interactions with fisheries, and acquiring inferred behavioural patterns over time. Studies looking into odontocete distribution, densities, population trends, habitat usage, and echolocation behaviour before, during and after industrial activities, benefit from T-POD (and/or C-POD) data. As an example, the T-POD has been used around wind farms, oil & gas rigs and platforms, aquaculture cage sites, in Marine Protected Areas (MPAs), and areas with low-density populations.

T-POD experts

Our team comprises highly qualified and experienced marine scientists with an in-depth knowledge of Passive Acoustic Monitoring (see www.passiveacousticmonitoring.com) and T-POD (and C-POD) applications. We provide project planning and implementation, including survey design, field technicians, deployment, and data analysis.

Ocean Science Consulting Ltd. (OSC) deploys PODs from and around Jack-up rig in the North Sea. © OSC 2012.

Ocean Science Consulting Ltd. (OSC) deploys PODs from and around Jack-up rig in the North Sea. © OSC 2012.

Rigs as artificial reefs & feeding stations for harbour porpoises (& other species)

Ocean Science Consulting scientists were the first in the world to acoustically monitor harbour porpoises (and other cetaceans) feeding around offshore oil and gas installations in the North Sea (free PDF) and showed the importance of offshore production platforms as a nocturnal feeding ground for porpoises in an area that had been over-fished. This study highlights the importance of rigs as artificial reefs (watch video) and prompted substantial media attention from newspapers and magazines such as New Scientist (read article), BBC Wildlife (read article), and opened up the debate on various online discussion forums (visit forums). Studies like these have prompted a swift re-evaluation of current rig-decommissioning rules in the North Sea, as there is increasingly strong evidence that rigs should be left in situ at the end of their operational lifetime.

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