CContrasting life-history strategies in the Ciénaga Grande de Magangué, a Neotropical floodplain: Reproduction, growth, and exploitation vulnerability of two endemic fishes
Year: 2025
Type: article
Abstract: The Magdalena River basin supports one of the most relevant inland fisheries in northern South America, yet biological information on many endemic species remains scarce. This study investigated the reproductive biology, growth, and exploitation of the characin Triportheus magdalenae and the freshwater sciaenid Plagioscion magdalenae in the Ciénaga Grande de Magangué, a Neotropical floodplain wetland in the lower Magdalena River basin. Monthly samples were collected from artisanal landings at three landing sites over a hydrological year (September 2016–August 2017), and 2,210 individuals (1,459 Triportheus magdalenae; 751 Plasgicion magdalenae) were analyzed. For each specimen, total length, weight, sex, maturity stage, gonadosomatic index (GSI), hepatosomatic index (HSI), and condition factor (K) were recorded. Fecundity of mature females was estimated, and length–frequency data were analyzed with FiSAT II to obtain growth and exploitation parameters for T. magdalenae and preliminary growth parameters for P. magdalenae. Basin-scale landings for 2021–2022 were obtained from the Colombian Fisheries Statistics Service (SEPEC). Both species showed distinct seasonal spawning peaks associated with the flood pulse (March–May), but with contrasting life-history strategies. T. magdalenae matured early (female L₅₀ ≈ 15.6 cm TL), exhibited high relative fecundity (~5,000 oocytes per female), and rapid growth (L∞ = 24.15 cm TL; K = 0.60 yr⁻¹). Total mortality (Z = 2.68 yr⁻¹) and Pauly natural mortality (M = 1.33 yr⁻¹) yielded a fishing mortality F = 1.35 yr⁻¹ and an exploitation rate E = 0.50, suggesting exploitation close to the conventional optimum for many tropical populations. In contrast, P. magdalenae matured later (female L₅₀ ≈ 29.9 cm TL), had fewer but larger oocytes, and lower growth rates; mortality and exploitation could not be robustly estimated due to limited length–frequency data. SEPEC data indicate that T. magdalenae and P. magdalenae together contributed ~2.8–5.4% of total basin landings in 2021–2022. Our results suggest that T. magdalenae currently tolerates moderate fishing pressure, whereas P. magdalenae appears more vulnerable, and support size limits and seasonal closures aligned with reproductive peaks in Neotropical floodplain fisheries. This study illustrates a scalable approach to assessing the exploitation status of endemic freshwater fishes in data-limited tropical river basins, providing empirical support to efforts to reconcile inland fish production with biodiversity conservation.
Language: English
Subfield: Nature and Landscape Conservation
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: diamond
OpenAlex ID: W7153261543