Growth and reproduction parameters estimation of Octopus vulgaris in the Moroccan Mediterranean by size frequency analysis

Authors

1 Agricultural and Aquaculture Engineering Research Team (ERG2A), Polydisciplinary Faculty of Larache, B.P 745, Main Post 92000, Abdelmalek Essaadi University, Tetouan, Morocco

2 National Fisheries Research Institute (INRH), Regional Center of Tangier, P.O. Box 5268, Tangier, Morocco

10.22092/ijfs.2025.133396

Abstract

A study of growth and reproductive parameters of Octopus vulgaris in the Moroccan Mediterranean (between Fnideq and Jebha) was carried out based on size frequency data of a sample of 14919 specimens (7891 females and 7028 males) from fishing trawlers and artisanal boats during 2015-2019. Different methods of FISAT II software including Powell-Wetherall, ELEFAN I, Shepherd, and Modal Progression Analysis were tested. Based on the annual sex ratio, females were slightly more abundant than males (1.06:1.00). Mature females were most abundant between June and September. Throughout the year, 53% of the males caught were mature on average. Length L50% and Weight TW50% were 15.56 cm, 2602.16 g for females and 10.77 cm, 991.30 g for males respectively. Compared with those found by other authors in the Mediterranean and Atlantic, and after the most appropriate growth parameters were selected, the Von Bertalanfy equation was estimated to be L(t)=28.76 (1- e-1.06(t - 0.386)) for combined sex. The size-age data obtained using the direct method and Bhattacharya's approach were substantially similar. The study of size frequencies from commercial data, even for octopus, would be a useful substitute to estimate size-at-age data required for stock assessment and fishery management.

Keywords

Iranian Journal of Fisheries Sciences
Volume 24, Issue 3
May 2025
Pages 505-525

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