Length-based estimates of growth parameters and population structure of Siganus rivulatus (Forsskål, 1775) from the Gulf of Suez, Red Sea, Egypt

Siganus rivulatus is an economic species that has been proven to move from the Red Sea to the Mediterranean region via the Gulf of Suez and its vital canal. Clarifying the current status of this species in the Gulf of Suez is the goal of the current study. 1161 individuals (10-24 cm of total length) were collected and examined during the 2022 fishing season from Attaka fishing harbor, Suez. The distribution of length frequency indicated the predominance of small sizes (12 and 13 cm). Body weight and length indicated an isometric growth pattern. Body girth and length were found to be correlated significantly with a linear relationship (r²= 0.824). The overall mean value of the condition factor (1.25) referred to a suitable habitat for growth. Four age groups were observed where 65% and 33.7% of the population belonged to the first and the second age groups, respectively. Von Bertalanffy growth parameters were estimated as 29.2 cm, 0.373y^-1 and -0.902y^-1 for L_¥, K and t₀, respectively. The growth performance index (Ø= 2.50) expresses a good fit for habitat. Mortality coefficients indicated a high value of fishing mortality (F=1.62 y^-1), exceeding the biological reference points. The length at first capture (14.90 cm) was less than that of first maturity (17.90 cm) and the optimum length (17.71 cm). The exploitation rate's value (E= 0.69) confirmed the state of over-exploitation. The study recommended tightening control over landing points, preventing the fishing of illegal sizes, and also reducing fishing effort with a rate of 46.4% to preserve the stock.