Abstract:
The purpose of this study was to determine the population dynamics and stock
assessment of the Nile tilapia. In Unnichchai Reservoir, it is the predominant fish that
is highly preferred by consumers. The length-frequency distribution, length-weight
relationship, growth and mortality parameters, and recruitment of the Unnichchai
reservoir were investigated using length-frequency data and respective weight. The
length-frequency distribution and length-weight relationship were computed from
linear regression analysis by using MICROSOFT EXCEL Professional plus 2019 and
growth mortality parameters and recruitment analyzed ELEFAN method incorporated
in FISAT software. 360 fish specimens sampled two times per month, from Gill net
haul over a period of 6 months starting from June 2023 to November 2023.
Oreochromis niloticus exhibited negative allometric growth (b: 2.02 (l 3) and near to
the strong positive correlation (t':0.8615). The von Bertalanffy growth constants for
Oreochromis niloticus were TL- :38.40 cm, K: 0.69 yr-1, and with a derived growth
performance index of $:3.00. The instantaneous rates of total mortality (Z), natural
mortality(M),andfishingmortality(F)were l.45,l.29,and0.16peryearrespectively.
The rate of exploitation (E : 0.ll) showed under-exploitation of this species.
However, this reservoir be stocked annually that may be to balance the rate of
exploitation of the Nile tilapia population. There might be a few possibilities for yearly
stocking, which would suggest that the reservoir experiences predator attacks, heavy
exploitation due to fishing, or inadequate natural recruitment. To solve that issue,
implement a regular monitoring program to identify and record the O. niloticus
population, improve natural recruitment, and increase public awareness of fisheries.
