Age, growth and mortality of the pearly razorfish Xyrichtys novacula (Linnaeus, 1758) (Labridae) in the Gulf of Tunis

Growth parameters and mortality rates were determined from a sample of 115 individuals of Xyrich-tys novacula collected with handlines in the same sector of the Gulf of Tunis between June 2015 and October 2019. The sample size range was between 9.8 and 19.2 cm total length (TL) with mean TL of females being significantly smaller than that of males. The estimated length-weight relationships were TW0.002 TL3.383 for males and TW0.003 TL3.320 for females, and both showed positive allometric somatic growth. Age was evaluated from whole sagittal otoliths and 6 age classes were determined. Von Bertalanffy growth parameters for the whole sample were: TL & INFIN; = 17.18 cm, K = 1.079 year-1, t0 = 0. Calculated growth performance index was 0 = 2.50 cm year-1. Total mortality (Z) was 1.3 year-1, natural mortality (M) was 0.949 year-1, fishing mortality (F) was 0.35 year-1, and exploitation rate (E) was 0.27 year-1.

Automated summary

Growth parameters and mortality rates of Xyrich-tys novacula were determined using a sample of 115 individuals collected between June 2015 and October 2019 in the Gulf of Tunis. The sample ranged from 9.8 to 19.2 cm total length (TL), with females having a significantly smaller mean TL than males. Length-weight relationships for males and females showed positive allometric somatic growth. Age was evaluated using otoliths, and 6 age classes were determined. Von Bertalanffy growth parameters for the whole sample were calculated, along with total mortality, natural mortality, fishing mortality, and exploitation rate.