Population dynamic of red snapper (Lutjanus gibbus) at Alor waters East Nusa Tenggara Province, Indonesia

Abstract

This study aims to analyze the population dynamics of red snapper in Alor waters, conducted from March 2018 to March 2019. Fish total length data is collected from red snapper fishermen twice a week using a stratified random method. Size structure, cohort numbers and average length of fish per cohort using Bhattacharya method, asymptotic length and growth rate using Ford and Walford methods, total mortality, capture and natural using linearized length converted catch curve using Pauly methods, exploitation rate and Y/R by Beverton and Holt methods. The results show that red snapper measuring 180-555 mm, male 220 - 555 mm, females 180 - 330 mm, consisting of four cohort, L∞ 594.25 mm, K 0.69 per year, F, M, and E are 0.84, 0.63 and 0.56 per year respectively, the actual Y/R and Y/R are optimal at 0.0773 and 0.0989 grams per recruitment. The conclusion that catches are dominated by young and pre-adult fish, population consists of four cohort, fish in the population quickly reach L∞, the ratio of F and M rate are greater than one (F/M> 1), high F rates cause high rate of E and impact on the recruitment process that is not optimal.