Length-based population parameters of shortfin scad (Decapterus macrosoma) in Bali Strait waters, Indonesia

Abstract

Shortfin scad (Decapterus macrosoma) is one of the most abundant catches of purse seiners in Bali strait. This study aimed to reveal the length-length relationship, the length-weight relationship, and to estimate the length at first maturity (Lm50) and the length at first capture (Lc50) for D. macrosoma in the waters of Bali Strait. The samples were collected from Pengambengan Fishing Port from June to December 2018. A total of 3,341 shortfin scads were fork length measured and weighed during the research. There were 420 fish from the total sample fish measured more for the total and standard length and dissected. The sex and maturation stage determination were identified by gonad visual characteristics. The relationship between lengths was determined using linear regression, whereas the length-weight relationship was determined using power regression. The length at first maturity and capture were determined using the logistic curve. The lengths (total, fork, and standard) were highly related to each other. The lengths were also highly related to the weight. The growth pattern of the shortfin scad was hyperallometric. The Lm50 for D. macrosoma was 164 mmTL for males and 162 mmTL for females. They were shorter than the Lc50, which was 184 mmTL.