Distribution pattern of Galeus atlanticus in the Alborán Sea (south western Mediterranean) and some sexual character comparison with Galeus melastomus

Abstract

Galeus atlanticus is a small-sized deepwater catshark living on the slope bottom of the Alborán Sea. Given its external similarities with Galeus melastomus, both species are often confused, which makes G. atlanticus a very poorly understood species both in terms of catches and biological aspects. For this study, a total of 741 G. atlanticus specimens, caught during scientific surveys from 1997 to 2003, were analysed. The distributional patterns were described and the reproductive status estimated. Galeus atlanticus occurred throughout the Alborán Sea, between the Strait of Gibraltar and Cape Gata, including the slope of the Island of Alborán. Its bathymetric range extended from 330 to 790 m and no size–depth trends have been observed. Mature specimens, both males and females, were caught in all seasons of the year. Size at first maturity was significantly different between sexes, with estimates of 32.9 cm for males and 36.9 cm for females. The differential growth of some secondary sexual characteristics, such as clasper length in males and oviducal gland diameter in females, were compared with those of G. melastomus.

Keywords:

• Alborán Sea
• depth distribution
• Galeus atlanticus
• geographical distribution
• Mediterranean Sea
• reproduction

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

The authors would like to thank all the participants of the MEDITS, MERSEL and REINBAN cruises and the crews of the R/V Cornide de Saavedra and Francisco de Paula Navarro for their collaboration in the sampling undertaken. The first author was working with a FPI/FSE grant from the Instituto Español de Oceanografía during the preparation of this manuscript. R. Coelho received a PhD grant (SFRH/BD/10357/2002) from FCT through programs POCI 2010 and FSE during the course of this work. We also wish to thank Chris Rodgers and Alberto García for the English text revision made during the preparation of the manuscript.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark