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Marine Scotland Science Reports

Informal report series, containing contract reports and preliminary or routine results of research and monitoring carried out by Marine Scotland Science.


UK Open Government Licence (OGL)

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Selecting a Bath Treatment for the Marine Carpet Sea Squirt Didemnum vexillum, Kott 2002 in Scottish Shellfish Aquaculture

Scottish Marine and Freshwater Science Vol 9 No 12
Following the identification of the invasive non-native species Didemnum vexillum, Kott 2002, on a Scottish shellfish aquaculture unit, a control method was needed to permit the legal movement of live Pacific oysters (Magallana gigas) off from the farm, and which would kill the pest species but result in acceptable mortality in the aquaculture species. Following a literature review, the most relevant control method in our case was determined to be a bath treatment. Twelve relevant published studies were found describing bath treatments for fouled shellfish, although some results were contradictory and their interpretation was complex. This report presents a review and analysis of the evidence needed to have a control method accepted for initial trial by the Scottish shellfish industry and by the relevant national regulatory authorities. The control method that will go forward for field trial is immersion in freshwater for a minimum of 24 hours. Associated data are presented for download.

Turrell, W. R., Robinson, C.D., Matejusova, I., Brown, L., Gubbins, M., Hermann, G., Graham, J. 2018. Selecting a Bath Treatment for the Marine Carpet Sea Squirt Didemnum vexillum, Kott 2002 in Scottish Shellfish Aquaculture. Scottish Marine and Freshwater Science Vol 9 No 12, 91pp. DOI: 10.7489/12128-1
Release Date
Spatial / Geographical Coverage Location
Several locations reviews, please see attached data and report
English (United Kingdom)
UK Open Government Licence (OGL)
Data Dictionary

The quantitative data extracted during this review was:
• Treatment Chemical (Formula);
• Strength of treatment chemical (% w/w active ingredient in water diluent);
• Immersion time in bath treatment (minutes);
• Time exposed to air before or after immersion (minutes) when relevant;
• Value of the mortality of the fouling species (0%-no mortality, 100%-full mortality);
• Value of the survival of the aquaculture species (0%-no survival, 100%-full survival).

Note the difference between fouling and aquaculture species effect quantification. We chose to present the extracted data as fouling organism mortality, and aquaculture species survival, as in both cases the ideal treatment, from the perspective of the shellfish aquaculture industry, would result in 100% values, e.g. 100% D. vexillum mortality with 100% shellfish survival. Data was extracted from the text, table and graphs of each data source. Values of fouling mortality and aquaculture species survival were most often digitised from graphs presented in the published papers. On occasion some data manipulation (such as data inversion) was required in order to get all of the data into the same form. Data conversions are summarised in the report appendix.

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Marine Scotland Science
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