donderdag 28 maart 2013

First 2 hauls and new storm warnings

We saw our first blue whiting marks on the echograms. The schools are not extremely big yet, but we wouldn’t expect them to be so in this southern part of the survey at this time of the year. We should hit the big stuff further North at around 56° North, just west of the shelf.

We do fishing, to ground truth our acoustic findings and to collect biological samples. 250 fishes are measured and weighted, from which we produce length-weight and length frequency relationships. Additionally 100 otoliths are read. Otoliths are the hearing stones of fish. They can be used to read the age of the fish, using similar methods as known to most of us from dendrochronology, or in other words, tree ageing. Put in simple words, we have to count the rings. This is a relatively difficult job as these stones are very small and have to be read under a microscope.

About the weather forecast…We can still claim to be fairly lucky with the weather up to now, given we are out on the Atlantic by the end of March. If we believe the weather forecasts, we should get into wind force 8 tomorrow and on Friday, which I would describe as being at least sub-ideal conditions…

Trawl 1

Time: 11:47 (UTC)
Position: 53°47' N    13°57'W

We hit the school quiet hard and got 5 tons of blue whiting in the net. It was what we would call a clean blue whiting catch containing nothing but blue whiting, 1 dealfish and 10 myctophids.

 Blue whiting school we targeted for haul number 1, as seen on the 38 kHz echosounder:


Trawl 2

TIme: 21:53 (UTC)
Position: 53°58' N    12°58' W

In the second catch we got up 2 tons, again pure blue whiting with 2 dealfishes, 2 squids and a few mesopelagics.

Blue whiting school we targeted for haul number 2, as seen on the 38 kHz echosounder:


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