Growth, reproduction and recruitment patterns of the wide-eyed flounder, Bothus podas Delaroche (Pisces: Bothidae), from the Azores

Abstract

The wide-eyed flounder, Bothus podas, occurs in many East Atlantic sub-tropical and temperate inshore areas and is the dominant flatfish in shallow-water areas around the Azores. The aim of this study was to examine the growth, reproductive biology and recruitment patterns of the wide-eyed flounder in the Azores. Adult fish samples were obtained by spear fishing and SCUBA hand netting at Faial Island. Juveniles were obtained from a complementary monthly beach-seining programme undertaken at Porto Pim Bay, Faial. Sex and development stage were determined by macroscopic examination of gonads, whereas age estimates were obtained by counting the number of opaque bands in the otoliths. In the Azores, B. podas reaches 6 years old, which is more than reported for the central Mediterranean, the only other population of this species that has been studied. The studied population has a sex ratio biased to males, which contrasts to a previous observational study, which noted a female-biased sex ratio. Spawning time, as determined from the gonadosomatic ratio and the macroscopic examination of gonads, was between July and September. This time period agrees with behavioural observations in the same area. Sexual maturity was estimated at a total length (TL₅₀) of 14.1 cm and at an age (A₅₀) of 1.7 years. Small juveniles occur on sandy inshore nursery areas for most of the year, but mainly between July and August each year. The presence of small fish throughout most of the year could suggest a protracted settlement period or slow growth on occasions on the shallow-water nursery grounds.

Keywords:

• Bothus podas
• growth
• insular populations
• maturity
• sex ratio
• spawning

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

Financial support was given by the Portuguese National Science Foundation (FCT) through the PRAXIS/3/3.2/EMG/1957/95 project, and PRAXIS grants BIC/1938/96 to TM and BIC/1930/96 to PA. The authors wish to thank D. Rosq for help with otolith readings and Ros several volunteers for help in data collection, namely J. Branco, F. Cardigos, A. Fernandes, J. Fontes, F. Gomes, C. Leal, M. Machete, O. Melo, F. Mendes and F. Tempera.

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