Age, growth, and feeding of boarfish, Capros aper (Linnaeus, 1758) in the Southwest of the Iberian Peninsula

ABSTRACT

The boarfish (Capros aper) is a pelagic species that appears on numerous occasions as bycatch or discard in trawl fisheries in the Northeast Atlantic and Mediterranean. Existing information on this species and its occurrence as bycatch is incomplete for the Atlantic coasts. The objectives of this work were to study its growth, ageing, and diet in the southwest of the Iberian Peninsula. We found that the length–weight relationship was TW = 0.022*TL^2.89 (R²= 0.94). We observed age classes ranging from 1 to 5 years and that otoliths vary in shape and size according to the age of the individual, becoming more irregular in the lateral areas and increasing the size of the central cleft as the specimens grow older. The parameters of the von Bertalanffy growth equation were L_∞ = 11.80 cm; k = 0.21 yr⁻¹; t₀ = −1.60 yr. Diet analysis indicated that copepods were the most abundant prey in the stomachs analysed, (IRI index value of 84.24%). This study serves to increase knowledge on the biology of the boarfish, which may be useful for future studies on the species, as well as for other members of the family and fisheries in which it is discarded.

KEYWORDS:

• Boarfish
• Capros aper
• Gulf of Cádiz
• otolith
• growth
• diet

Acknowledgements

The authors would like to thank Zaida Parra and Félix Macías for embarking on fishing vessels and collecting the specimens sampled. We would like to thank Lucía Vicente Chacón for the drawing of the otoliths, as well as Beñat Egidazu de la Parte for his help in making the map where the sampling was carried out. Thanks also to Sam Blakeman for helping us to improve the English version of this manuscript, for her comments, suggestions, and revision. We would also like to express our gratitude to INMAR (Instituto Universitario de Investigación Marina) for allowing us to use their laboratories to carry out all the precision measurements. We would also like to thank the anonymous reviewers whose contributions have helped to improve and enrich this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).