Management of Mystacoleucus padangensis population by the determination of the optimum length at first capture for its exploitation in Lake Singkarak, West Sumatra-Indonesia

Abstract

Abstract The Lake Singkarak locates on Solok and Tanah Datar Regency, West of Sumatra-Indonesia which has 10,908.2 ha surface area and 178 m average of depth. The fish biodiversity in this lake was high, among of them was the native fish species of bilih (Mystacoleucus padangensis) which pose an important economic value. The population of bilih has been decreasing caused by the overexploitation and habitat degradation. The resource management effort on the bilih fish was conducted through a determination on the needed conservation area as well as regulation on the location for capturing and restocking of the fish. The objective was to the determine the optimum length of the fish at the first capture (Lc_opt) as a function of F/M for conducting a sustainable exploitation. The primary and secondary data were used in this study. The fish samples were caught on four stations using several experimental fishing gears in July 2019. The biological obtained data (population parameters, growth pattern, and reproduction) were collected from the secondary data. The length at first mature of male and female of bilih were 7.5 cm and 8.2 cm, respectively. The value of Lc_opt for F=3.86 M was 11.2 cm, while it would be of 10.0 cm for F=M and 9.5 cm for F=0.5M. Those values were larger than the first size of the mature gonads which suggested that bilih enable to reproduce. The exploitation conducted on the value of Lc_opt would give the maximum yield per recruitment and maintain population size above half of the natural abundance.