1. To carry out mackerel egg survey (ICES Triennial Survey), on the western shelf and slope in the area from 52N to 59N.
2. To collect fish samples, by trawling, for atresia and fecundity analysis back at the laboratory.
The vessel will be loaded on the afternoon of 13 March in Ullapool and when ready proceed to the first plankton station west of the Butt of Lewis. Plankton stations will be taken west along the line 58 45N until zero eggs are found and from there the vessel will head due south and then continue sampling back eastwards along the transect at 57 45'N. Subsequent transects south of this will be at 1 degree intervals with stations at 30' E/W intervals. Plankton stations will be taken using the Gulf VII sampler with mounted CTD which will record salinity and temperature during the tow. The plankton tows will require the vessel to deploy the sampler at 1-2 knots, and then steam at 5 knots. The sampler will then be lowered at a steady rate (10m/min) from the plankton crane to within 5 m of the seabed or 200 m - whichever is shallower. The sampler will then be recovered at the same speed. Once aboard, plankton samples will be washed from the sampler net, fixed in formalin and scored for egg abundance. Trawl samples will be taken at the discretion of the scientist in charge. There should be a maximum of 12 trawls for the whole survey and will usually be taken at the shelf edge. The precise length of each transect cannot be defined in advance as this survey uses an adaptive design, where sampling along a transect will continue until there are no or very small numbers of eggs.
Once the transect at 52 45'N has been completed and depending on the time available the survey will proceed back north surveying the transects missed out during the first half. The vessel will return to Ullapool for unloading on 27 March 2013.
Normal contact will be retained with the laboratory throughout, and with other vessels taking part in the survey.