Age, growth and reproduction of Raja miraletus (Linnaeus, 1758) (Chondrichthyes: Rajidae) of the Gulf of Gabès (Tunisia, Central Mediterranean Sea)

Abstract

Age and growth of the brown ray, Raja miraletus, was estimated from ring counts on vertebral sections from 95 females (13.5–56.0 cm total length (TL)) and 85 males (13.5–58.0 cm TL) collected from the Gulf of Gabès (Central Mediterranean, Tunisia) during 2007. Marginal increment and edge analyses suggest annual band pair formation. The oldest female and male brown rays were 9 and 7 years old, respectively. Von Bertalanffy growth parameters are L8 = 69.20 cm TL, k=0.18 year^–1 and t ₀=–0.11 years for females, and L8 = 67 cm TL, k=0.22 year^–1 and t ₀=–1.01 years for males. Longevity estimates were 19.25 and 15.75 years for females and males, respectively. Based on life history parameters, natural mortality estimation M was in the range 0.37–0.47 for females and 0.60–0.61 for males. Males were found to mature between 28 and 43 cm TL and L_50% was estimated at 34.31 cm TL (21.91 cm DW). Females mature between 33 and 48 cm TL and reached L_50% at 41.8 cm (27.10 cm DW). Age at sexual maturity (A_50%) was estimated at 2.7 years for males and 4.41 years for females. Females and males have an annual reproductive cycle. Mating occurred mostly through spring and summer.

Keywords:

• Age
• growth
• Gulf of Gabès (Tunisia)
• longevity
• maturity
• Mediterranean Sea
• natural mortality
• Raja miraletus

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

We thank the staff of the laboratory of sclenochronology of aquatic animals (IRD, LEMAR, France) for providing technical support. We also wish to extend our thanks to the anonymous reviewers for comments that greatly improved the submitted 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