1. To conduct an acoustic survey to enhance the precision of the survey carried out by MRV Scotia to provide an estimate of the abundance and distribution of herring in the northern North Sea (ICES area VI and VIa(N)) as part of the ICES International North Sea Herring Acoustic Survey.
2. To obtain samples of herring for biological analysis, including age, length, weight, sex, maturity and ichthyophonus infection.
All gear will be transported to Fraserburgh by lorry and van on 9 July and loaded onto the vessel. Installation and testing will take place on 9 July. Scientific staff will travel by mini-bus to Fraserburgh to join the vessel on the morning of 10 July and the vessel will depart on the same day.
MRV Scotia, which has previously only covered area IV, will be including the area Via(N) north of the Butt of Lewis. The survey will be carried out within an area bounded by 58° 30'N to 62°N and 08°W to 2°E. Echointegration will be carried out at 38, 120 and 200 kHz. Data from the times between 2300 and 0300 will not be used for stock assessment. Trawling operations will be carried out when the skipper has identified commercially viable marks. Samples of all species caught will be measured for length and weight to establish a length weight relationship. Otoliths will be collected from a sub-sample of the herring to determine age. The maturity state and. presence of Icthyophonus infection will also be recorded.
A map of the proposed survey track is given below (Figure 1). The intention is to survey mid way between MRV Scotia transects (dotted line). This will allow an increase in the number of transects sampled in areas of high fish density, as close to simultaneous with Scotia as possible
The survey will involve following a pre-set survey pattern, at a steaming speed of approximately seven to ten knots depending on the position of Scotia relative to the charter vessel. A port call will take place at an approximate half way stage in Lerwick to provide a rest day in accordance with working time directive for a trip of this length
All gear will be unloaded in Fraserburgh for return to the laboratory by lorry and furniture van. Staff will return on the same day by minibus. Normal contact will be maintained with the Marine Laboratory, MRV Scotia and the appropriate Fisheries Officers.
Eric Armstrong (Marine Scotland Aberdeen Marine Laboratory)
ICES International North Sea Herring Acoustic Survey
International Council for the Exploration of the Sea (ICES)