Royal Netherlands Institute for Sea Research

Little cuttle fish

It is Spring again and the NIOZ fyke is up and running for 2016, and the first catches are in. Besides various fish species we are also catching a lot of invertebrates, including crabs, shrimps and jellies. All fish and invertebrates are daily counted and recorded.

After clearing the trap the counting starts.

Return of the crabs

 As the Green Crab returns from the North Sea numbers in the fyke have risen from 1 or 2 in the first week of March to 300 at the beginning of April. A lot of females have moulted and bear eggs. Other crabs to be found now are the Swimming Crab, the Chinese Mitten Crab and the big Edible Crab. They return to the Wadden Sea for food or to breed. Hermit crabs have also returned and are being recorded in the net.


The Brown Shrimp is the most often recorded species in the fyke but we also catch a lot of Common Prawn, a southern species whose prevalence has been increasing in recent years. In the 1990s we only caught 10 per year, but by last year this figure had risen to 1000. In the last week alone we caught five specimens, one with eggs. Two species of comb jellies are also now occurring in our catches: the Sea Gooseberry and the invasive species, Mnemiopsis leydii. Both these species survive the winter and start up a new stock in spring.

Little Cuttlefish

A very nice species to observe at this time of year is the Little Cuttlefish. This species of about 4 cm in length acts like a Common Cuttlefish, with quickly changing colours and tentacles in ‘attack’ mode, making it look like the mouse that roared.