Life Span, Maximum Age and Growth Pattern of the Blackspot Snapper Lutjanus ehrenbergii (Family: Lutjanidae) from Two Different Areas in the Red Sea, Egypt

Since the ability of exploited populations to sustain harvests is influenced by their demographic characteristics, the present study aimed to investigate the longevity and growth patterns of the blackspot snapper (Lutjanus ehrenbergii) landed in Hurghada and Suez. A total of 356 and 345 specimens were regularly collected each month for one year during the active fishing season. These specimens were measured and dissected to determine their sex. The total length (TL) of each specimen was measured to the nearest 1mm, and the total weight was taken to the nearest 0.1g. Scales and otoliths were collected for age determination. The ages were calculated by counting the alternating translucent and opaque bands in sagittal otoliths and scales, which were validated as annuli. The maximum lifespan was found to be 5 years for both sexes and in both studied regions. For L. ehrenbergii collected from Suez, the von Bertalanffy growth function (VBGF) parameters were L∞ = 32.81cm, K = 0.311 y⁻¹, and t₀ = -1.21 years, while for those collected from Hurghada, the parameters were L∞ = 30.61cm, K = 0.359 y⁻¹, and t₀ = -1.91 years. The growth performance in length (ΦL) values were nearly identical, with values of 2.52 for Suez and of 2.53 for Hurghada. Furthermore, L. ehrenbergii exhibited negative allometric growth for males in Suez and positive allometric growth in Hurghada. Females showed isometric growth in both areas. The growth exponent (b) values were as follows: 2.67 for males, 2.97 for females, and 2.98 for combined sexes from Suez; and 3.26 for males, 3.02 for females, and 2.95 for combined sexes from Hurghada. This information should encourage fisheries managers to consider growth variations when implementing fishing regulations and management policies for L. ehrenbergii stocks from these two landing sites.