Seasonal abundance of the Atlantic bobtail squid Sepiola atlantica in Galician waters (NE Atlantic)

Abstract

The abundance of the bobtail squid Sepiola atlantica was assessed for Areamilla beach at Ría de Vigo. Sampling was carried out monthly and simultaneously by two scuba divers at two sandy submersed zones between December 2007 and November 2009. A total of 505 specimens of S. atlantica (204 juveniles, 149 males and 152 females) were collected. The mean annual abundance of the species was 0.01±0.01 ind./m² from December 2007 to November 2008, and 0.02±0.01 ind./m² from December 2008 to November 2009. Abundances were not significantly different between the two depth zones for each year, nor for seasons. However, total abundance was significantly different between seasons. Abundance showed a seasonal pattern with the lowest values in summer. For each season populations were formed by specimens of different size during the two sampling years, as well in both depth zones. Spawning occurs throughout the year. Two peaks of recruitment, one in summer and another in autumn, were observed. Whether seasonal differences in abundance are due to migration of the individuals from shallow to deeper zones related to changes in bottom temperature is discussed.

Keywords:

• Abundance
• NE Atlantic
• Ría de Vigo
• seasonal patterns
• Sepiola atlantica

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 are greatly indebted to Prof. Sigurd von Boletzky (Observatoire Océanologique de Banyuls sur mer, Laboratoire Arago) for his attention, time, and fruitful advice, as well as the hosting facilities offered in his institute. Thanks to Eva Šatović (Ruder BoŠković Institute) for her cordial help with the English. The first author was supported by a financial grant ‘Movilidad de Estudiantes para la Obtención de la Mención Europea en el Título de Doctor’ from the Ministerio de Educación (Spain) and a fellowship from the programme Axudas Predoutorais from Universidade de Vigo.

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