FRV Alba Na Mara 1514A
|Ship name (ship code)||FRV Alba Na Mara (74NM)|
|Cruise period||2014-08-25 — 2014-09-10|
|Port of departure||Fraserburgh, United Kingdom|
|Port of return||Fraserburgh, United Kingdom|
1. To obtain estimates of the distribution and abundance of Nephrops burrows in the Firth of Forth, Moray Firth and, if time allows, off Arbroath using underwater cameras.
2. To use the TV footage to record the occurrence of other benthic fauna and evidence of commercial trawling activity.
3. To collect trawl caught samples of Nephrops for comparison of reproductive condition and morphometrics in each of the different survey areas.
4. If time permits, deployments of the sledge and then the drop frame will be carried out on the same ground to compare Nephrops burrow density estimates obtained using the two different methods.
Where possible, a random stratified approach will be adopted to investigate Nephrops burrow density in different regions of the study areas. A list of proposed stations for the survey will be made available for the ship on the day of loading.
1. TV Observations: At each station a video camera mounted on a sledge will be towed across the seabed for approximately 10 minutes at approximately one knot. Nephrops burrows abundance, other benthic fauna and signs of anthropogenic activity will be recorded on to DVD. Distance traveled by the sledge, the depth at which the sledge is at and camera height from the seabed will be monitored and recorded using a range finder mounted on the sledge.
2. Trawling: Fishing trawls of approximately 30 minutes duration will be made within each sediment type within each survey area. A range of biological and morphometric data will be collected on Nephrops and other shellfish obtained from the catch.
3. Drop Frame: The drop frame will be used where conditions are not suitable for using the TV sledge, recording similar data as to that of the TV sledge.
4. Comparative work: Following on from work carried on previous surveys the sledge will be deployed in very close, parallel tracks approximately 200 m in length (10 minutes towing time) on known Nephrops grounds. Video footage and all observed data will be recorded as usual. Following this, the drop frame will be drifted across the same area at 90o to the sledge tracks. The frequency of this operation will depend on the weather and time available.
The burrow density estimates obtained using the different set ups will be compared. This work will take place on the first half of the trip, irrespective of area the vessel will be working in at the time.
|Chief scientist||Adrian Weetman (Marine Scotland Aberdeen Marine Laboratory)|
|Specific||Firth of Forth, Moray Firth.|