Ballast Water Sampling and Sample Analysis for Compliance Control - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 192

For the net mesh size it is recommended to use a mesh of 36 ʼ m in square

dimension, which results in a diagonal dimension of 50 m. This is in line with

Guidelines G8, i.e., “If samples are concentrated for enumeration the samples
should be concentrated using a sieve no greater than 50

ʼ

ʼ m mesh in diagonal

dimension.”
The plankton net should at best be equipped with a removable cod-end, prefera-
bly with fi ltering panels so that the sample can be concentrated effectively during
the sampling process. A valve at the bottom of the cod-end is benefi cial as it eases
the extraction of the concentrated sample. Should multiple samples be taken, it is
recommended that the fi ltering sieve of the cod-end can be replaced between the
sampling events so that no organisms become stuck from one sampling event and
could be erroneously added to another sample. An example of such a net with a
removable cod-end is given as Fig. 3 .

Wash Bottle

For cleaning of the plankton net an unbreakable wash bottle may be used. Such a
wash bottle may also be used when emptying the cod-end content, i.e., to concen-
trate the sample into an (unbreakable) sample bottle to ensure that all organisms
caught are transferred into the sample bottle. An example is given in Fig. 4 .

Fig. 3 Plankton net for
in-line sampling with a
removable cod-end with
fi ltering panels (David 2013 )