Marine

MRV Alba na Mara: Survey 1615A Programme

October 20, 2015 by Marine Directorate Communications No Comments | Category Compliance, Marine Directorate general, Marine Directorate Science, Research Vessel Surveys

Objectives:

1. To conduct an acoustic survey designed to survey both the open and enclosed areas of the Clyde to ultimately provide an estimate of the abundance and distribution of herring and sprat.
2. To obtain samples of herring and sprat for biological analysis, including age, length, weight, sex, maturity and ichthyophonus infection.
3. All other species caught will be measured for length and weight to establish a length weight relationship.
4. Data will be gathered on cetaceans using a towed passive acoustic array.

Procedure:
Fishing gear will be transported to Mallaig on 22 October and loaded onto the vessel. Scientific staff will travel by car to Mallaig, and join the vessel on 23 October. The vessel will make passage on 24 October to the Clyde to commence the survey on 25 October at the earliest opportunity.

The survey will be carried out within an area bounded by approx. 55°N to 56°N and 04° 40’ W to 05° 40’ W. Echo-integration will be carried out at 38, 120 and 200 kHz. Data gathered in the hours of darkness will not be used for stock assessment. Trawling operations will be carried out as and when marks are identified.  Otoliths will be collected from a sub-sample of the herring and sprat to determine age. The maturity state and. presence of Icthyophonus infection will also be recorded.

The track will be similar to that carried out on previous surveys (Figure 1).

A passive acoustic array will be towed during the survey, to detect the presence of cetaceans throughout the survey area. Thermosalinograph data will be gathered throughout the survey.

The survey will involve following a pre-set survey pattern, at a steaming speed of eight knots. At the end of the survey the vessel will aim to be in Fraserburgh for unloading on the morning of 7 November.

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