Created with Wolfram Mathematica 9.0
Using only directed trawls
For estimation of capelin abundance it can be a problem that there may be too few trawl stations that are directed towards echosounder registrations - most of the trawlings may be either bottom trawls or 0-group trawls, especially after the so-called ecosystem surveys started. To investigate the effect of this, the setting useOnlyDirectedTrawls ensures that all trawl stations used has quality 2.