Tracking small cetaceans under water to inform collision risk: developing a tool for industry.

This work aims to provide industry with system to fill key knowledge gaps on the distribution of small cetaceans at tidal turbine sites assisting the timely and cost effective development of tidal powered renewable energy generation in an environmentally safe manner.

If mankind is to control atmospheric carbon dioxide levels and manage climate change, and if the UK is to meet its legally binding carbon reduction targets, it will be essential to make full use of all appropriate technologies for renewable power generation. The UK is fortunate in having substantial potential for generating renewable power offshore. Tidal power has the unique advantage amongst renewables technologies of being completely predictable and is thus a particularly valuable component of any renewable energy portfolio. Tidal stream turbines are site in tidal rapid areas. These are rather small and unusual habitats which have comparatively little studied. One of the main environmental concerns with the use of tidal stream generators is that large animals such as marine mammals will be in collision with the rotating blades and suffer injury or even death. All cetaceans are European Protected Species.
To assess collision risk we need to know the probability that animals will be in the vicinity of rotating turbine blades. This is a function of both the two dimensional spatial density distribution of animals and their distribution with depth. This information is currently lacking at all UK tidal rapid sites. This lack of knowledge introduces both environmental and economic risks. Planning consent applications are being delayed, onerous and costly mitigation measures may be placed on developers and development may initially be allowed only on a "deploy and monitor" basis which carries the risk for developers that devices may have to be removed if collisions do indeed occur. There are well developed methods to determine the two dimensional distribution and density of cetaceans. However, we believe the only practical technique to measure dive depth and underwater behaviour in these challenging habitats it so use drifting vertically oriented arrays of hydrophones to locate vocalising animals by time of arrival difference techniques. It was this conviction that led us to start working to develop such systems, and the software to analyse the data they produce, in 2009. Since then we've developed and thoroughly tested a system which is deployed from a drifting vessel. Field tests have shown that the system provides reliable and accurate locations and that animal vocalisation can be linked into tracks to reveal underwater movements and we are building a significant dataset of new information on porpoise underwater behaviour at putative tidal sites, mostly in Scotland.

To be widely useful to industry however, the system needs to be sufficiently straight forward for industry and their consultants to deploy routinely. We've largely achieved this with the software by incorporating it into PAMGUARD, a feely available open sources cetacean detection, localisation and tracking package. However, the hardware is somewhat cumbersome, reflecting its origins as a research and development system. We are confident that recent technological developments provide several options for developing an affordable, self contained autonomous buoy-based system that can be hand deployed from a small boat e.g. a Rhib and the operate autonomously. This should be straight forward for non-specialist teams to utilise in the field and because a much smaller vessel is required field costs should be substantially reduced. We've also identified hydrophones as an area where we can provide knowledge to allow substantial cost savings.

This proposal aims to take the knowledge and IP from the existing system and repackage it in a less expensive and more easily used buoy based system and make this, along with customised software, freely available as an open source resource.