Aspects of the growth and reproductive biology of Oreochromis niloticus (Linnaeus, 1758) in a tropical Soda Lake, Lake Shala, Ethiopia

Abstract

Morphometric relationships, condition factor (CF) and reproductive biology are significant tools in fish stock management, fish biology, physiology, conservation and ecology. Growth and reproductive strategy of Oreochromis niloticus were studied from 343 fish specimens collected from Lake Shala between January and December 2018. Fish samples ranged from 7.7 cm to 33.0 cm in total length (TL) and from 7.80 g to 708.21 g in total weight (TW) were collected using gillnets of 4, 6, 8, 10, and 12 mm mesh sizes. The length-weight relationship of O. niloticus was TW = 0.0104TL 3.19 , indicating positive allometric growth of the fish. The sex ratio (0.93:1) was insignificant from the ideal fish distribution of 1:1 (χ 2 = 0.47, p > 0.05). Mean CF for males, females and combined sexes was 1.04, 1.06 and 1.05, respectively and statistically insignificant (p > 0.05). The spawning peak occurred in July (rainy) and February (dry) periods, as defined by ripe females and the breeding season. Absolute mean fecundity was 806 eggs and correlated positively with TL and TW of the fish (p < 0.05) (F = 0.56TL 2.29 , R 2 = 0.93, p < 0.05; F = 18.83TW 0.67 , R 2 = 0.90, p < 0.05).The study provides the first detailed account of the morphometric relationships and reproductive biology of O. niloticus in Lake Shala, which can be used as baseline information for successive biological-based studies in Soda Lakes of Ethiopia.

Biological aspects of Oreochromis niloticus (Linnaeus, 1758) in Geray Reservoir (Ethiopia) for effective sustainable fisheries

“…According to Das et al (2021) and Huang et al (2022), fish length-weight relationships can be used to assess fish length and age structures, population dynamics, growth, mortality rate, and overall health. These are essential tools for collecting information on fish health, stock assessments, and population management (Wagaw et al, 2022). The condition factor is used in fisheries science to evaluate the fitness condition of fish (Wagaw et al, 2022;Wagaw et al, 2024).…”

“…These are essential tools for collecting information on fish health, stock assessments, and population management (Wagaw et al, 2022). The condition factor is used in fisheries science to evaluate the fitness condition of fish (Wagaw et al, 2022;Wagaw et al, 2024). Using the coefficient value generated by length-weight relationship data, the condition factor can also be used as a tool for studying the lifespan of fish (Huang et al, 2022).…”

“…Using the coefficient value generated by length-weight relationship data, the condition factor can also be used as a tool for studying the lifespan of fish (Huang et al, 2022). However, both biotic and abiotic environmental factors have a significant impact on fish health (Wagaw et al, 2022).…”

“…Understanding fish reproductive biology is essential for fisheries management and for filling the knowledge gap in fundamental fisheries research (Tesfaye & Wolff, 2014;Wagaw et al, 2022). Reproductive biology information, such as spawning period and fecundity, is essential in the study of fish biology and population dynamics, as well as in the assessment of the reproductive potential of individual fish species (Das et al, 2021).…”

“…This will enhance the routine evaluation of numerous econom-ically important fish species and advance our understanding of stock health (Tesfaye & Wolff, 2014). Additionally, having access to data on reproductive characteristics and environmental changes may enhance our ability to estimate recruitment and help us comprehend the variations in reproductive output that have been observed (Wagaw et al, 2022). Data on reproduction and fecundity of O. niloticus can provide essential information for efficient resource management (Das et al, 2021;Huang et al, 2022).…”