Population dynamic of indian scad (Decapterus russelli) based on data in tasikagung fishing Port of Rembang

Abstract

Indian scad is a small pelagic fish that has important economical value. Indian scad caught by mini purse seine which is the most dominant fishing gear in Tasikagung Fishing Port of Rembang. The high demand of Indian scad, in fishermen enlarging their effort. The purpose of this research is to know the growth, mortality rate, exploitation rate and reproduction aspects including gonad maturity level and gonad maturity index of Indian scad. The research was conducted in January – April 2019. The method used was systematic random sampling. Data collected were size of fish (mm), weight (gram), weight of gonads (g) and catching area. The samples were collected twice a month. The length of fish ranged from 102 - 185 mm. The length-weight relationship analysis obtained equation W = 0.0000546TL2.73 and L50% 155 mm. Estimation of Von Bertalanffy growth equation is L∞ = 221 mm, K = 1.7 year−1, and the time of zero length (t0) = -0.322 year. Total mortality (Z) of indian scad was 2.91 year−1, natural mortality (M) was 1.48 year−1 and the fishing mortality (F) was 1.43 year−1. This indicates that the rate of exploitation of indian scad amounted 0.49 year−1. The pick recruitment occurred in August and September. The average Indian scad caught in the condition of maturity on gonad maturity level III and IV. Gonad maturity index of male Indian scad was 1.47 and females was 1.59.