Age-Dependent Parameters of the Von Bertalanffy (1938) Growth Model: A Case Study of Sardinella aurita (Valenciennes, 1847) along the Central Algerian Coast (Southeastern Mediterranean Sea)

Background: Small pelagic teleosts, notably the round sardinella (Sardinella aurita), constitute a fundamental component of marine ecosystem structure and reinforce regional food security. Nevertheless, the long-term sustainability of these stocks is increasingly threatened and compromised by synergistic pressures of intensive fishing exploitation and fluctuating environmental factors.

Aims: This study aimed to introduce a modified growth model for short-lived pelagic fish that integrates age-dependent variability with the objective of refining biomass estimates and optimizing stock assessment protocols.

Methods: Monthly biological sampling was conducted from January to December 2023 along the central Algerian coast, yielding a total of 1,128 specimens. Two distinct growth formulations were evaluated: the conventional von Bertalanffy Growth Function (VBGF), which assumes a constant growth coefficient K, and an age-dependent approach in which the parameters (Kn, L∞n) were estimated independently for each identified age cohort.

Results: Comparative analysis revealed two distinct growth scenarios. The conventional VBGF scenario, characterized by slow growth (K = 0.31 year-1, L∞ = 30.90 cm), projected a maximum lifespan (Tmax) of 10 years. Conversely, the age-structured model (Kn) exhibited rapid early growth (K1 = 2.27 year-1) that progressively decelerated to 0.46 year-1 by age five, projecting a maximum lifespan of 7 years — although only five age classes were resolved from the sampled population, likely attributable to intense fishing pressure. Asymptotic lengths (L∞n) ranged from 9.35 cm at age one to 25.10 cm at age five. The growth performance index (Φ′) varied from 2.29 to 2.50 across age classes, with a coefficient of variation (CV) of 4%. Total mortality (Z) was estimated at 3.97 year-1. Under the age-structured scenario, natural mortality (M) decreased with age, from 1.10 year-1 at age one to 0.43 year-1 at age five, in contrast to a static baseline M 0.39 year-1 across all cohorts; meanwhile, fishing mortality (F) increased with age, from 2.87 year-1 at age one to 3.54 year-1 at age five, compared to a constant F of 3.58 year-1.

Conclusions: The age-dependent model (Kn) offers a more robust and biologically realistic depiction of the growth and life-history dynamics of S. aurita, thereby supporting sustainable management practices that account for rapid early growth and reproductive energy allocation. This data-parsimonious mathematical framework offers a highly practical alternative for stock assessments in data-limited fisheries, particularly where complex bioenergetic modeling is logistically unfeasible.

Keywords

Pelagic Species Age Structure Growth Coefficient Bioenergetics Food Security Mediterranean Sea
  • University of Algiers 1, Faculty of Sciences, Department of Life Sciences, Laboratory of Living Resources of Economic Interest in Algeria (REVIECO), 2 Didouche Mourad Street, Algiers
  • Mohamed Toumi
    University of Algiers 1, Faculty of Sciences, Department of Life Sciences, Laboratory of Living Resources of Economic Interest in Algeria (REVIECO), 2 Didouche Mourad Street, Algiers
  • Rachid Amara
    Univ. Littoral Côte d’Opale, CNRS, IRD, Univ. Lille, UMR 8187, LOG – Laboratoire d'Océanologie et de Géosciences, Wimereux, F-62930, France

How to Cite

Azaoui, R., Toumi, M., & Amara, R. (2026). Age-Dependent Parameters of the Von Bertalanffy (1938) Growth Model: A Case Study of Sardinella aurita (Valenciennes, 1847) along the Central Algerian Coast (Southeastern Mediterranean Sea). The North African Journal of Food and Nutrition Research, 10(21), 223-233. https://doi.org/10.51745/najfnr.10.21.223-233

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