Grey skate

Scientific: Dipturus batis. English: Grey skate, blue skate, skate. Icelandic: Skata. For more languages see the Marine Animal Dictionary.

Biology and distribution

The grey skate is a very large skate species, usually around 100 to 150 cm long, but can reach almost 3 m in length. It is found all around Iceland, but is much rarer in the colder waters north and east of the country. It occurs over a wide depth range, from 10 to 1000 m depth, most often between 100 and 200 m, shallower in the summer. It only exists in the Northeast Atlantic from Murmansk in the north to Morocco in the south. A closely related species, the barndoor skate (Dipturus laevis) is found off the northeast coast of North America.

The grey skate feeds on a variety of food, both benthic invertebrates and fishes. Large skates mainly eat other fishes. It presumably matures late and grows slowly, but as with other cartilaginous fishes, it is difficult to age determine them.

Catch and fishing methods

The grey skate provided the bulk of the reported skate and ray catches in the past; the other species either being too small to be of interest or living in deep waters out of reach for the fishing gear. The grey skate is fished in a variety of fishing gear throughout the year, but with a spike in catches in May and June.

Stock status

The grey skate used to be fairly common in Icelandic waters, but has been overfished as catches are now only about 10% of catches 50 years ago. There is no TAC on the grey skate as it is primarily a bycatch in a variety of fisheries. The status of the grey skate stock can be compared to the halibut stock as both species are at a low level. Both are widely distributed, fished in many types of fishing gear, very large and mature late.

Processing and markets

Large part of the catch goes to local consumption as the grey skate is a very traditional food in Iceland. The bulk of this is eaten on December 23^rd. The other half of the catch is processed in a variety of ways and mainly exported to Belgium where it is eaten fresh.

Icelanders prepare the skate by salting or fermenting it. The Icelandic way of fermenting the skate is quite simple; the skates are put in a pile on the deck of the boat or on the seashore, and there they lie for a few months. During this process the urea in the blood is broken down into harmless ammonia compounds. Harmful bacteria that would otherwise cause the flesh to rot (to become putrid) are kept away by the high acidity and by other harmless bacteria during this process. It is commonly thought that Icelanders eat putrid skate, they do not! The skate is not putrid! The Greenland shark is processed in a similar way. However, the shark is eaten raw while the skate is always boiled.

The strong ammonia smell of a well-prepared skate is supposed to stop your breath temporarily and subsequently clear your sinuses. It is supposed to be a good remedy for the common cold. Research has not supported that but it has not disproved it either.

References and further information

References: (Jónsson & Pálsson, 2006).

For full citation and further information on the main species in general see this page

Hreiðar Þór Valtýsson, University of Akureyri