CURRENT STATUS OF THE POPULATION DYNAMICS OF NILE TILAPIA (Oreochromis niloticus) IN BATUR LAKE, BALI, INDONESIA

A study aimed at evaluating the population dynamic parameters of Nile tilapia (Oreochromis niloticus) was conducted at Batur Lake, Bali, Indonesia from March to November 2023. The research was based on a survey, with fish samples obtained from the catch of fishermen using gillnets with a mesh size between 1.0 and 4.0 inches. The findings indicated that the population of Nile tilapia in Batur Lake was predominantly characterised by individuals with a mean length of 20.5 cm, which represented a frequency of 11.2%. The observed growth pattern was allometric (+). Analysis conducted using the FISAT Programme Package revealed that the maximum length (L∞) of the fish is 34.75 cm, with a growth rate (K) of 0.56 per year. The natural death rate (M) is 1.11 per year while the death rate due to fishing (F) is 1.35 per year. Consequently, the total death rate (Z) is 2.46 per year, resulting in an exploitation rate (E) of 0.55 for the Nile tilapia population. Currently, the Nile tilapia in Batur Lake can spawn more than once a year, with peak spawning periods occurring in March, June, September, and November. The natural mortality rate (M) is 1.11 per year and the mortality rate from fishing (F) is 1.35 per year, leading to a total mortality rate (Z) of 2.46 per year, which confirms the exploitation rate (E) of 0.55. Based on recruitment patterns, the Nile tilapia in Batur Lake is capable of spawning multiple times annually, with the busiest spawning seasons occurring around March, June, September, and November.