Biological Aspect of Indian Scad (Decapterus russelli) Caught by Purse Seine in North Coast of Sumenep Waters, East Java

Abstract

An Indian scad (Decapterus russelli) is one of the dominant catch in Java Sea. Sustainability of Indian scads resources need to be maintained due to its important role and fisheries economic value especially in purse seine fisheries. This research was conducted in Sumenep Regency from February until July 2018 which aimed to determine the biological aspects and food composition of Indian scads (Decapterus russelli). The method in this research is descriptive and using random sampling method. A total of 1,078 fish samples obtained with Total Length (TL) ranged between 13.5-23.7 cm and body weight between 21.23-132.3 grams. The Indian Scads growth pattern was negative algometric with equation W = 0.02L2.736. Male and female ratio was 1:1.08. The value of Gonado Somatic Index (GSI) was 1.76%. The Lm value was 19.3 cm. That was higher than the Lc value (18.6 cm). Growth parameters of Indian Scads indicated that asymptotic Length (L∞) was 25 cm, K was 0.58 and t0 age was -0.29 years and age of t max was 4.9 years. It was found that the main food of the Indian scads was phylum Ochrophyta (IP> 72%). The Indian scads growth pattern was negative allometric. Gonad Maturity Level (GML) analysis indicated that the samples were dominated by immature fish. Lm value of 19.3 cm was higher than the value of Lc (18.6 cm). The Indian scads were categorized as plankton feeder types.