From 6 May 2019, Wageningen Marine Research will go out to sea again for the triennial mackerel egg survey in the North Sea. This survey is part of the international Northeast Atlantic mackerel and horse mackerel egg survey. Due to logistics, the North Sea mackerel egg survey is always conducted in the year after the large Atlantic survey. The aim of this survey is to estimate the spawning stock of mackerel and horse mackerel through their egg production.
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Ewout Blom, Dirk Burggraaf, Betty van Os, Thomas Pasterkamp, Ineke Pennock en Cindy van Damme will be sampling mackerel egg on board Tridens for the next four weeks. Every week the entire North Sea will be sampled. Thus, Tridens will cover the North Sea four times during this survey.
The water column will be sampled for fish eggs with a Gulf VII plankton torpedo (see picture). Eggs of mackerel will be collected from the samples and counted. This will give an estimate of the total egg production during this spawning season. With a pelagic trawl adult fish will be caught to estimate the number of eggs produced by one female.
This survey is part of the ICES-coordinated international survey. In contrast to the Atlantic survey in 2016, which was carried out by 13 institutes, Wageningen Marine Research is the only survey participant in the North Sea. De results of the whole survey are used in the spawning stock biomass estimate of mackerel carried out by ICES.
In June, Wageningen Marine Research scientists will return home with hopefully lots of mackerel eggs on board.