Age, Growth and mortality of the rabbit fish Siganus rivulatus (Forsskål 1775) from the Egyptian Mediterranean coast off Alexandria, Egypt

Desouky Et Al., Mohammed G.

doi:10.21608/ejabf.2022.264477

Age, Growth and mortality of the rabbit fish Siganus rivulatus (Forsskål 1775) from the Egyptian Mediterranean coast off Alexandria, Egypt

Document Type : Original Article

Author

Mohammed G. Desouky et al.

10.21608/ejabf.2022.264477

Abstract

The present work aimed to provide essential information to assess proper management for the rabbitfish, Siganus rivulatus on the Egyptian Mediterranean coast in Alexandria, Egypt. A total of 1116 specimens of rabbit fish were collected from the Egyptian Mediterranean coast off Alexandria during the fishing season of 2021 to study the length-weight relationship, age and growth, mortality rates and exploitation rate. The length-weight relationship showed that the S. revulatus growth was nearly isometric (b= 2.935). Age was determined by the otolith-reading technique and its longevity reached five years. The age groups (II+ and I+) were most abundant in the fishing sample. The back-calculation method estimated that the maximum annual increment in length (10.44 cm) was recorded during the first year of life; while the maximum annual increment in weight (23.54 g) was recorded during the fourth year of life. The values of the von Bertalanffy growth parameters were L∞ = 22.8 cm; W∞= 143.53 g; K = 0.341 year^-1 and t₀ = -1.376 year^-1. The mean total mortality "Z" was 1.66 year^-1. The natural mortality "M" was estimated as 0.68 year^-1, and the fishing mortality rate (F) was 0.95 year^-1. The exploitation rate (E) was estimated as 0.59. The length at first catch was 14.56 cm.

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