last few miles

The last week end of the survey was spent in Newcastle-upon-Tyne where the Tridens was docked upriver close to the city.

Tridens underway up the river Tyne towards Newcaslte

The final survey week will now cover the remaining transects in the southern part of the survey area covered by the Netherlands:

Soon after restarting again on the survey track, the net was shot at some aggregations below a dense plankton layer on the sea bed:

haul 17: 14/07/2014 @ 18:34 UTC (55º17'N 1º07'W)

The catch consisted of small herring, ranging between 16.5 and 23 cm. The same was true for the following trawl aimed at more dense individual schools further offshore:

haul 18: 15/07/2014 @ 07:29 UTC (55º17'N 0º27'W)

During these trawls, the GoPro camera was again installed in the net to monitor the capture process:

young herring entering the net during haul 18

monitoring of the capture process using a trawl sonar located on top of the net: the square shape represents the outline of the net which is towed just over the sea bed (seen as a straight pink line). One of the herring schools can be observed entering the trawl.

smaller herring of mean length 20 cm seen in the south of the survey area

Hendrik Jan and John sampling the catch

During the hauling process of trawl station 18, a new broadband echosounder was trialled to collect data on herring schools over a wide frequency band. The data will be used as part of a collaborative science-industry project aimed at improving fish species identification:

screenshot showing acoustic broadband backscatter data (95 - 160 kHz) of a herring school

On the 55º17'N transect, another test trawl aimed at mackerel just below the surface was done. Again, the catch after 30 minute trawling contained a few baskets of mackerel:

the caught mackerel ranged from 29-38 cm, mean length: 32 cm

Hendrik Jan as the centre of attention during the biological sampling process

Acoustic detections on the most recent transects showed mostly aggregations of smaller herring (black circles on the map below) with a few hot-spots with more dense schools. No more Norway pout (red circles on the map below) was seen towards the south of the survey area. However, in the survey area covered by Scotland, just north of us, increased amounts of young 0-group Norway pout were also observed.

Only a few more transects to go now before returning back to Scheveningen after a 4 week journey...