Mislabelling drives skate to brink of extinction

Nov 18, 2009
A rajidae skate swims in the Mediterranean off southern Turkey. Due to an 83-year-old error of classification, a species of European skate could become the first marine fish driven to extinction by commercial fishing, according to a study released Wednesday.

A species of common skate is to become the first marine fish species to be driven to extinction by commercial fishing, due to an error of species classification 80 years ago, reveals research published today in the journal Aquatic Conservation.

The European common skate, Dipturus batis, has been on the World Conservation Union's Red List of Threatened Species since 2006, with France currently being responsible for 60.2% of reported landings. These catches are predominantly registered under the name 'D.batis,' however researchers, led by Dr Samuel Iglésias, show that 'D. batis' is in fact two clearly distinct species which have been incorrectly categorised as one since the 1920s.

From the mid-19th century the common skate was described as two distinct species, the flapper skate, D. intermedia, and the blue skate, D. flossada. However, in an influential work in 1926 R.S Clark recognised only 'D. batis' as a valid species and this classification has largely gone unchallenged since.

This classification confusion has resulted in the depletion of the flapper skate, the more endangered species of the two, being masked in the catch record. This means the risk of extinction is far higher than previously assessed and without immediate and incisive action the species may be in an irreversible decline towards extinction.

When conducting sampling in fish markets during the start of this study Dr Iglésias observed noticeable morphological differences in the 'Dipturus batis' specimens he sampled. In order to understand these differences the researchers not only analysed the systematic molecular data but also reviewed the species' life history and analysed fishery statistics.

"As the species was listed as 'Critically endangered' I wanted to understand who's who? I estimated at the beginning that it would take some weeks to resolve this question, but in the end it took me about two years," said Iglésias. "Our research clearly shows that D. cf. flossada and D. cf. intermedia are distinct and should be resurrected as two valid species."

Common Skates, which were once abundant in British and European waters, have been in sharp decline for decades. In 2008 the International Council for the Exploration of the Sea (ICES) noted that the species is depleted in the Celtic and North Seas, the Skagerrak and the English Channel. The ICES advised no target fishing and that by-catch should be minimised.

"The threat of extinction for European Dipturus together with mislabelling in fishery statistics highlight the need for a huge reassessment of population for the different Dipturus species in European waters," concluded Iglésias. "Without revision and recognition of its distinct status the world's largest skate, D. cf. intermedia, could soon be rendered extinct."

Source: Wiley

Explore further: No-take marine reserves a no-win for seahorses

add to favorites email to friend print save as pdf

Related Stories

Radically-Designed Skates Improve Performance

Jan 20, 2005

This spring, California-based LandRoller will introduce the first major innovation in skating in over 25 years. Its radical new skate design cranks up performance to take skaters to places – and surfaces ...

Over 100 new sharks and rays classified

Sep 18, 2008

(PhysOrg.com) -- Australian scientists have completed an ambitious 18-month project to name and describe more than 100 new species of sharks and rays.

Recommended for you

No-take marine reserves a no-win for seahorses

11 hours ago

A UTS study on how seahorses are faring in no-take marine protected areas (MPAs) in NSW has revealed that where finishing is prohibited, seahorses aren't doing as well.

Dolphin hunting season kicks off in Japan

16 hours ago

The controversial six-month dolphin hunting season began on Monday in the infamous town of Taiji, but bad weather would delay any killing, a local official told AFP.

User comments : 0