Blog post
News from the herring/sprat front
After the week end break we started the final leg of this year’s survey, indicated in blue below.
Soon after starting the first transect (18.7.2011, 11:10UCT at 54º24N 0º58W), we came across some schools:
Let’s shoot the net!
the catch turned out to consist of mackerel, herring, sprat and whiting… a typical North Sea mix!
samples are taken for herring and sprat to determine lengths, weight, maturity, age and sex.
Ages are determined by cutting out the otoliths, calcarious stones that are part of the balance organ. They lay down rings every year similar to a tree.
In sprat, they can be very small, and a lot of patience is required:
A last check before they are glued into plastic trays ready to be read back in the lab:
