first survey week & net camera trials

Towards the end of the first survey week, another 4 hauls were done on the transects going east out of the Moray Firth and back west again towards north east Scotland. Just east of the Halibut Bank, some further herring aggregations were encountered as seen on the echograms just before the different trawl stations:

haul 7: 03/07/2014 @ 14:26 UTC (57º52'N 0º09'E)

haul 8: 03/07/2014 @ 18:45 UTC (57º52'N 0º52'E)

haul 9: 04/07/2014 @ 09:10 UTC (57º40'N 0º28'E)

 These aggregations stretched out continuously along the seabed for several miles

The catches gave again a few tonnes of herring:

Being a bit more south in our survey area, the herring were now a few cm smaller than the previous samples caught further north. Mean lengths were around 25cm:

 

sampling a catch of herring

When entering the shallower waters of the Halibut Bank again on the southern transect going west, we saw some marks again over several miles. These stretched even further west towards the coast. The echograms below give an indication of the situation seen just before and after haul 10:

haul 10: 04/07/2014 @ 14:20 UTC (57º40'N 0º12'W)

The catch turned out to consist of small Norway Pout. There is a lot of them around!!

towards the end of the week, the weather was picking up a bit

During the past few hauls we were trialling a GoPro camera in the net. The aim of this was to get a better picture of "what is entering the net at what depth and time". As the first trials were done without the light source, it was evident that the pictures below 60m depth were too dark. During the last haul, the camera and LED light source was placed within the trawl tunnel. The pictures showed the stream of young Norway Pout continuously entering the net. However, there were also a few mackerel present!:

this mackerel was swimming happily along within the trawl for several minutes! The individual small Norway Pout (~5cm) can only be seen as little light rays shooting through the picture.

The camera/light system will now be tested during herring trawls this week. More to come!

The following bubble plot gives an indication of the distribution and densities of herring observed during the last week:

 

 This week, we will now be covering the following transects: