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Ecological effects of electrofishing for Ensis spp. in Scotland. Fiona Murray 1,3, Phil Copland 2, Phil Boulcott 2, Mike Robertson 2 and Nick Bailey 2.

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Presentation on theme: "Ecological effects of electrofishing for Ensis spp. in Scotland. Fiona Murray 1,3, Phil Copland 2, Phil Boulcott 2, Mike Robertson 2 and Nick Bailey 2."— Presentation transcript:

1 Ecological effects of electrofishing for Ensis spp. in Scotland. Fiona Murray 1,3, Phil Copland 2, Phil Boulcott 2, Mike Robertson 2 and Nick Bailey 2 1 Razorclam Fishermen’s Forum. 2 Marine Scotland Science. 3 Present address Heriot-Watt University 1

2 Overview Previous razor clam study in Scotland Aim of this project Sea trials Tanks trials Conclusions and implications 2

3 Hydraulic dredge 3

4 4

5 Electrofishing https://www.youtube.com/watch?v=Z02KhkOgfVQ 5

6 Aims of this project: Sea Trials Record recovery rates of Ensis spp. Identify non-target species which may be affected by Ensis electrofishing Record the recovery of non-target species Determine if electrofishing may cause mortalities in sandeels Observe the impact of the electric rig on the seabed 6

7 Sea trials Electrodes dragged over seabed Quadrats placed for 30 min 7

8 8

9 F99,96, p =

10 Pictures of all animals identified 10

11 Non-target results and sandeels F 34 = p = Sandeels 11

12 Determine the properties of the electric field generated by electrofishing Record the behavioural response to, and recovery from exposure to, an electric field in E. siliqua and 3 non target species Monitor the short term survival of E. siliqua and 3 non target species following exposure to an electric field Aims of this project: Tank Trials 12

13 Tank trials 13

14 14

15 15

16 Ensis siliqua https://www.youtube.com/watch?v=o1gcuYmPK6 w https://www.youtube.com/watch?v=o1gcuYmPK6 w 16

17 Non-target species Pagurus bernhardus Spisula solida Asterias rubens 17

18 Conclusions Electrofishing (using this system) is a potentially low impact method of harvesting razor clams. The impact on the seabed is minimal in comparison to conventional dredge and trawl fisheries. Immediate effects on non-target species are non- lethal and effects on invertebrate behaviour are short term. 18

19 Suggested next steps Initial stock surveys – ideally while derogation is sought Surveys by chartered commercial vessels using electrofishing technology linked to quantitative camera based system. Candidates for IFG coordination with industry input to design? Assuming derogation granted – allow commercial fishery based on initial survey findings. Vessels participate in data gathering Reassess stocks with knowledge provided by fishery and survey Adjust scale of fisheries as required and set catch opportunities 19

20 Thanks for listening 20


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