Population structure of bada (Rasbora maninjau Lumbantobing, Daniel N, 2014) caught using “lukah” in Batang Air Stream

Abstract

Abstract Inlets of Lake Maninjau are the fishing area of bada (Rasbora maninjau), one of them is Batang Air Stream. Bada fishing intensively, which is not balanced with conservation efforts, causes the fish population to gradually decrease and even become rare. Bada fishing activities at this location using “lukah” (trap) has been carried out and owned from generation to generation. This study aims to determine the population structure of bada using “lukah” in Batang Air Streams based on conservation efforts. Fish sampling was carried out in March, April, and June 2019. Fish samples obtained from three “lukah”. The size structure (length and weight), growth patterns (length-weight relationship), the gonadal maturity stage (GMS), and the sex ratio of bada were measured in this study. The results showed that the length and weight of bada in March, April, and June were found with a range of lengths of size 12-127; 63-125; and 73-113mm and weight were 1.8-14; 1.9-13.6; and 3.1-11g, respectively. The value of b ranged from 2.64 to 2.92. Isometric growth was found in March and April, which means the growth of length was balanced with the growth of the weight, and June is negative allometric. The highest frequency of GMS IV, which means the fish are ready to spawn, was found in March 2019. Therefore, during this survey period, it was might be a peak of the spawning period. High frequency (≥50%) of mature bada was found at length 71.5-99.5 mm for females and 65.5-77.5 for males. It is shown that most of the bada in “lukah” was mature. The sex ratio between male and female fish is 1:1.