Scottish Marine and Freshwater Science Vol 9 No 3
This report describes surveys carried out in the Sound of Harris and Ayrshire coast, Clyde in late August and early September 2017. A combination of commercial electrofishing rig and towed video rig was deployed at potential razor clam grounds using the fishing vessel ‘Nicola Jane’. Recorded video was analysed for the number and sizes of razor clams forced to the surface by the electrofishing equipment. Data were converted to area densities (numbers of razor clams m-2) based on estimates of the area swept (m2) by the video recording. The aim of this project was to use a combination of electrofishing with towed video to assess the quantities and sizes of razor clams (Ensis sp.) across a number of grounds on the west of Scotland. The results are intended to inform Marine Scotland in the setting of catch limits for potential commercial-scale fisheries on razor clams using the electrofishing technique.
Associated data are presented for download.
Data and Resources
- Scottish Marine and Freshwater Science Vol 9 No 3pdf
PDF of the report
- Razor clams - densities by towcsv
Description of field, format, units.
Ship = Ship name
- Razor clams - sizes by towcsv
Field descriptors for RazorClamSizesByTow.csv – description of field, format...
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Mon, 07/31/2017 - 23:00 to Fri, 09/29/2017 - 23:00
UK Open Government Licence (OGL)
|Data Dictionary|| |
Fifteen tows were completed in the Sound of Harris and all razor clams observed were Ensis siliqua. Generally low densities of clams were found varying from zero to 0.215 m-2. Most of the area surveyed was likely too exposed to favour razor clams with clean, largely featureless sand occupied by the occasional crab or small fish. The only tows with higher densities of razor clams (>0.1 m-2) were in, or adjacent to, the more sheltered Sound of Berneray. Forty-two tows were completed along the Ayrshire coast between Irvine and Girvan. These revealed a few areas with densities above one razor clam m-2, for example some tows between Girvan and Turnberry Point. For all other tows in Culzean Bay (north of Turnberry Point), Meikle Bay (just south of Troon) and North Bay (just north of Troon) densities were in the range 0.023 to 1 razor clam m-2. The size distributions of razor clams (E. siliqua) across all sites appeared rather similar with two modes, one at around 120-130 mm and the other around 175 mm. These modes possibly represent two age groups but there was little evidence of large numbers of smaller recruiting clams at any of the sites. The use of the combined electrofishing and towed video rigs to assess razor clam stock abundance worked well with 9-13 tows being completed each day when weather permitted surveying. The video recorded was generally of sufficient quality to allow identification of objects with only a few tows having parts obscured by macroalgae, sea-grass or sediment kicked up by the sled.
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Marine Scotland Science
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