Two 2-week deployments at the Billia Croo (BC) wave site were carried out (typically 3–5 m wave height). The first in a tidally influenced area with up to 3.5 m/s spring tides. The second was at a non-tidally influenced area of the wave site with up to 1.5 m/s spring tides.
The FLOWBEC device was deployed at the tidally influenced site from 10 Jul – 24th Jul 2013 and at the non-tidally influenced site from 27 Jul – 12 Aug 2013.
The FLOWBEC unit uses a vertical swath imagenex 837B Delta T and a vertically-mounted Simrad EK60 multi-frequency echosounder. The imagenex active sonar is used for target tracking, classification and observations of behavioural responses of fish, diving seabirds and marine mammals. The vertical swath orientation of the Imagenex gives coverage of the full water column, but with a relatively narrow horizontal band, which will not cover the full swept area of the turbine. The vertical swath and position (upstream / downstream of the turbine) means the unit can monitor the full water column.
The EK60 echosounder operates at 3 frequencies (38, 120 and 200 kHz) and is used for target classification (i.e. debris, fish, diving birds, mammals etc.), species identification for those species with known frequency response, and abundance estimates at all depths throughout the entire water column. At this point, species with known frequency responses include commercial fish and auk (seabird) species.
Contact Benjamin Williamson