May Facebook Twitter Whatsapp Google Linkedin Email Mackerel stage 5-eggs and recently hatched mackerel larvae, with a yolk-sac that is clearly visible. The egg survey is a true cooperation between science and the pelagic fisheries, in which not only research vessels, but also pelagic trawlers are used as a platform from which to conduct the survey. Collected eggs will give an estimate of the total egg production and thereby the stock of mackerel and horse mackerel in the spawning season. In the Dutch Caribbean, a shark reserve has been opened. The shark populations are steeply declining worldwide and therefore need additional protection against illegal fisheries and bycatch of regular fisheries. Researchers monitor the sharks and the diversity of fish species on the reefs with underwater stereo-video-equipment. Newly hatched elvers return to Europe from the Sargasso Sea. Data on the numbers of elvers entering the Netherlands are of crucial importance in keeping track of the eel population. Wageningen Marine Research has been monitoring this since 1938 at the outlet sluices of Den Oever and currently also at many other locations in the Netherlands. Every year, researchers of Wageningen Marine Research visit seal colonies on the Wadden Sea islets Griend and Richel. The new-born pups and adults are counted and photographed from a safe distance. That way, we can find out if female seals have their pups in the same spot each year. Salt marshes are of great importance to the Wadden Sea. Mud fields, gradually changing into pioneer marshes, have unique flora and fauna and serve as high water shelter and foraging ground for birds. To foster the development of salt marshes, a so-called 'mud motor' is employed.