Estimation on growth parameters of Arius maculatus (Thunberg, 1792) along the Thanlwin River Estuary comparing with the observed length and back-calculated length of otolith

This study examined the growth patterns of the spotted catfish, Arius maculatus (Thunberg, 1792) in the Thanlwin River Estuary throughout the analysis of standard lengths obtained from observed otolith data and back-calculated data. Between April 2023 and January 2024, 516 fish ranging in standard lengths from 8.3 to 33 cm were collected. The annual deposition of annuli in otoliths was confirmed using the marginal increment ratio, with ages ranging from 2 to 9 years. The Dahl-Lea back-calculation method expanded the length at age data to 2472 records for ages 1–9 years. Growth was characterized using Von Bertalanffy growth curves, revealing the significant differences between the observed data (asymptotic length L∞ = 25.34 cm, growth coefficient K = 0.257 year−1 and growth performance index ϕ′ = 2.02) and the back-calculated data (L∞ = 36.23 cm, K = 0.087 year⁻¹ and ϕ′ = 2.21). The findings of the study suggested that the back-calculated otolith data were more dependable for determining growth parameters compared to the observed otolith data. A. maculatus appears to exhibit slow growth characteristics, suggesting that the environmental conditions in the Thanlwin River Estuary may be deficient for this species. The insights gleaned from this research are crucial for guiding and shaping fishery management policies through informed advice and recommendations.