FRV Alba Na Mara 0114A
|Ship name (ship code)||FRV Alba Na Mara (74NM)|
|Cruise period||2014-01-06 — 2014-01-23|
|Port of departure||Fraserburgh, United Kingdom|
|Port of return||Fraserburgh, United Kingdom|
1. To obtain estimates of the Nephrops habitat distribution in South Minch sea lochs, using sediment grabs and underwater cameras.
2. To obtain estimates of the distribution and abundance of Nephrops within these lochs using underwater video cameras.
3. To compare two different methodologies to establish Nephrops burrow abundance (sledge compared to drop frame).
4. To use the video footage to record occurrence of other benthic fauna and evidence of commercial trawling activity.
5. To collect trawl caught samples of Nephrops for comparison of reproductive condition and morphometrics.
This survey continues on from the work previously completed in the sea lochs of the North Minch where the extent of the muddy Nephrops habitat was mapped in areas where there is little or no BGS data available.
For each area within the survey, a position outwith the suspected Nephrops habitat boundary will be selected as the start point for a search path across the length or breadth of the area. Along this search path the drop frame will be deployed to provide a visual record of the seabed type as the ship drifts over the ground. A Day Grab will be deployed at a suitable point along the track.
The search path will continue in one direction until the presence or absence of muddy sediment becomes apparent. The distance between, and the duration of, each of these deployments will vary in each area surveyed depending on the environmental conditions, unforeseen obstructions (creels, fish farms, etc.), the size of the survey area and how quickly the boundary between Nephrops and non-Nephrops habitat is detected.
Once an area has been satisfactorily surveyed to establish the extent of the muddy habitat, a selection of stations will also be surveyed for Nephrops abundance. The vessel will drift over the grounds whilst a 10 minute recording is made of the sea bed, during which time the number of Nephrops burrow complexes will be recorded. A sediment grab will be required following each of these operations.
Weather permitting, the areas in order of priority to be covered in this survey are Loch Hourn, Loch Nevis, Sound of Arisaig, Loch Sunnart and Sound of Sleat.
In a separate exercise, a comparison study between the Nephrops burrow complexes observed between the drop frame and sledge will be carried out.
Trawling will take place when suitable, with length, sex and morphometric data being collected for DCF and MSS purposes.
|Chief scientist||Adrian Weetman (Marine Scotland Aberdeen Marine Laboratory)|
|General||Inner Seas off the West Coast of Scotland|
|Specific||South Minch sea lochs|