Deepwater skates (Rajidae) collected during the 2004 cruises of R.V. “G.O. Sars” and M.S. “Loran” in the Mid-Atlantic Ridge area

Orlov A., Cotton C., Byrkjedal I.

Date de parution: janvier 2007
Volume: 30
Number: 4 suppl.
Pagination: 035-048
Editeur: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/2006-304supp-007
Résumé

The fauna of deepwater skates of the North Atlantic is insufficiently studied. Many deepwater species were discovered rather recently (second half of 20th century) and are known from a few records only. In the summer 2004, studies of bottom ichthyofauna were conducted aboard Norwegian R.V. “G.O. Sars” (bottom trawls, depths down to 3,500 m) and longliner M.S. “Loran” (bottom longlines, depths down to 4,500 m) off the Mid-Atlantic Ridge (MAR) area from Azores to Charlie-Gibbs Fracture Zone. Only four species were identified, these were Richardson’s ray Bathyraja richardsoni, pale ray Bathyraja pallida, Jensen’s skate Amblyraja jenseni, and Bigelow’s ray Rajella bigelowi. Richardson’s ray has until present been considered a rather rare species. It was described in the earlier 1960s from waters off New Zealand and subsequently found occasionally at great depths in the western and eastern North Atlantic. According to published data, the captures of only 66 specimens of this species are known to date. Our study showed that B. richardsoni is a common skate in the area surveyed. The 151 specimens captured by the R.V. “G.O. Sars” and M.S. “Loran” allowed us to obtain new data on external morphology and distribution of this species. A capture of a single specimen of B. pallida represented the first for the MAR area. This skate, which was also described in the 1960s, has been known until present by records of twelve specimens only in the Northeast Atlantic from the Bay of Biscay to Rockall Trough. A. jenseni was also captured for the first time in the MAR area. This species was reported mostly from off the coasts of Canada and USA and only several captures have previously been known from the Northeast Atlantic. The records of juveniles and adults in postspawning condition, testify that the MAR area is a regular part of the range of A. jenseni, which is not limited to coastal waters of both sides but extends far into the open Atlantic Ocean waters. R. bigelowi was represented in catches by two neonates. Some morphological characters of the specimens examined neither fitted the original description nor published data that probably related to limited number of neonates of both species examined to date.

Mots-clés: ANE - Deepwater - distribution - External morphology - Mid-Atlantic Ridge - Rajidae - Range - Records - Skates
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