Dipturus intermedius
The skate is is a member of the family of rays (Rajidae) ad the order of the rays and skates (Rajaformes). It is the largest endemic ray species, most frequently found on a depth of 100 to 200 meters. Juveniles prefer shallower waters. Giant skates feed on wurms, smelt, flatfish and crabs. The giant skate used to be common along the Dutch and Belgian shores, but the number of sightings has decreased dramatically.
The giant skate lays eggs, and is therefore oviparous. The green eggs are deposited in pairs, in spring and summer. They change to brown during their development. The eggcases are large and can measure 13 x 24 cm.
- Maximum length: 285 cm
- Maximum weight: 975 kg
- Maximum lifespan: 50 years
- Habitat: maximum 1000 meter depth
- Catches: there is a zero allowable catch for the giant skate North Sea.
- Status: ‘Critically Endangered’ on the international IUCN Red List (http://www.iucnredlist.org/).
Previously, the Giant skate was called Dipturis batis, but genetic research (Taxonomic confusion and market mislabelling of threatened skates: important consequences for their conservation status, Iglésias, Toulhoat, Sellos, published november 2009), has revealed that this were fact two distinct species: Dipturus intermedius and Dipturus flossada. The two species appear to have different, partly overlapping distributions that seem to be related to water temperature and different biological characteristics. Of the two, D. intermedius is slower growing and larger. The first data published suggests a size at 50% maturity of 197.5cm for females and 185,5cm for Dipturus intermedius, compared to 122.9cm and 115cm for males Dipturus flossada. The largest positively identified specimen of D. flossada was 143.2cm in length. It seems the maximum total length of 285cm previously attributed to D. batis must be D. intermedius.
This taxonomic confusion put into question all previously accumulated data based on D. batis. Its endangered status highlights the need for an extensive reassessment of population collapses with accurately identified species.
Distribution
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