Biological aspects of Indian scad (Decapterus russelli Ruppell, 1830) in south site of Madura Strait Waters, East Java

Indian scad (Decapterus russelli) are one of the pelagic fisheries resources in the Madura Strait. The Probolinggo area of the Madura Strait contributes to the scad (Decapterus spp) fisheries production in East Java, Indonesia. The purpose of this study was to observe the biological aspects of Indian scad (D. russelli) caught in Probolinggo waters which were landed in Paiton (in 2017) and Mayangan (in 2018). The method used was descriptive, with a random sampling technique. Sampling was carried out in Paiton, Probolinggo Regency (January 2017-May 2017) and Mayangan fishing port, Probolinggo City (December 2017-April 2018). Results showed that the growth pattern of Indian scad in Paiton was allometric positive (W = 0.0049L^3.2882) while in Mayangan it was allometric negative (W = 0.014 L^2.8513). The sex ratio (male:female) was 1:1.67 in Paiton and 1: 1.14 in Mayangan. Gonad maturity stages I to IV were found in this study. Gonad maturity of male and female fish was dominated by stages I and II with 79% immature and 21% mature fish in Paiton; 68% immature and 32% mature fish in Mayangan. The mean gonado somatic index (GSI) was 0.83%in Paiton and 0.76% in Mayangan. Length at first capture (Lc) and length at first maturity (Lm) in Paiton were 15.1 cm and 17.1 cm, respectively, whereas in Mayangan Lc and Lm were 15.9 cm and 16.9 cm, respectively. The catch was dominated by immature fish so that fishing efforts need to be controlled to enable sustainable resource use.