Reproductive biology of the mackerel scad Decapterus macarellus (Cuvier, 1833) from the southern waters of western Java, Indonesia

Abstract

The mackerel scad, Decapterus macarellus, is a one of pelagic fish that holds significant market price for the citizens of West Java. Despite this, there has been a puzzling decrease in catches recently. This study describes the reproductive biology of mackerel scad, D. macarellus, in the southern waters of western Java. Mackerel scad samples were collected once a month from July to December 2022 at three locations: Ciwaru Fish Landing Base, Palabuhanratu Nusantara Fisheries Port, and Binuangeun Fish Landing Base. A total of 1,000 fish specimens were obtained, consisting of 544 males (125–331 mm Fork Length, FL) and 456 females (124–322 mm FL). The number of males and females was imbalanced, indicating a discrepancy in the expected 1:1 ratio. The mackerel scad has a varying reproductive potential, with the number of eggs ranging from 35,391 to 167,915. Mature males and females were found from July to December, with the highest GSI occurring between August and November, indicating reproductive season from July to December and spawning peaks from August to November. The estimated sizes at which males and females reach first maturity were 238 mm and 240 mm, respectively. We recommend increasing gear mesh size to reduce catches of immature individuals, as the first catch was smaller than the size of the first matured gonads.