FRV Alba Na Mara 0512A
|Ship name (ship code)||FRV Alba Na Mara (74NM)|
|Cruise period||2012-03-27 — 2012-04-04|
|Port of departure||Fraserburgh, United Kingdom|
|Port of return||Fraserburgh, United Kingdom|
1. To measure horizontal drag forces for three different Nephrops trawls, over a range of speeds and sediment types.
Loading will take place on 24 March and two of the trawls will be rigged onto the net drums. Alba na Mara will leave Fraserburgh on 27 March and steam towards Burghead Bay. Day grab samples will be taken to confirm the sites sediments are suitable prior to fishing i.e. sandy mud and muddy sand. The rest of the cruise will be dedicated to gear trials. Alba na Mara will return to Fraserburgh where the scientific personnel and equipment will be unloaded on 4 April.
Single trawl fishing will be conducted on both sandy mud and muddy sand sediments for each of the three Nephrops trawls. The trawl will be fitted with load cells, Scanmar and flow meter instrumentation prior to deployment. Once the trawl is shot and settled on the seabed it will be towed at increasing speeds (2.0, 2.5, 3.0, and 3.5 knots) for 15 minute periods (~1 hour overall). The trawl will then be heaved to the doors, allowing Alba to turn, then reshot heading in the reciprocal direction. Sampling will continue going back and forth for approximately 4 to 5 hours per haul. Sampling will be cut short if the trawl comes fast or a load cell weak link is broken. The codend will be left open while towing to stop the variable build up in the catch affecting the overall drag of the trawl. However, if time permits towards the end of the cruise, some additional trials may be conducted with the codend closed.
|Chief scientist||Keith Summerbell (Marine Scotland Aberdeen Marine Laboratory)|
|Track charts||(00 MB)|