Modeling the linear growth of Paretroplus dambabe in the Makary zone of Lake Kinkony (Mitsinjo district, Madagascar)

Environment Science

In this article, the growth parameters (asymptotic length L∞, growth coefficient K, theoretical age to) of the Paretroplus dambabe fish, an endemic species of the Mahavavy Kinkony Complex in Mahajanga traditionally fished in the Makary area river, were studied. These parameters were determined from size frequencies using LFDA (Length Frequency Data Analysis V 5.0© 2001) software. The estimated values of L∞, K, and t0 found for our species were then substituted into the Von Bertalanffy growth equation in order to plot the growth curve. The linear growth performance index Φ was calculated according to the equation of Pauly and Munro (1984). The results obtained show that the growth parameters of female and male P. dambabe fish in the Makary area are very similar and the growth curves have exactly the same profile. The asymptotic length L∞=26.19 cm, established separately for males and females, overlap, indicating that there is no difference in growth between the sexes. The growth coefficient (K) differs slightly: females (K=0.93 year-1) reach adult size faster than males (K=0.83 year-1), probably due to adaptive strategies favoring early maturity. The theoretical conventional age at which Paretroplus dambabe has zero length (t0) is closer to zero for females (t0=−0.07 years), indicating early growth, while that of males (t0=−0.23 years) reflects initially slower growth. Female Paretroplus dambabe specimens have a higher size growth performance index Φ than males and, conversely, a shorter lifespan (tmax = 3.22 years) compared to males (tmax = 3.61 years).

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