Biological aspect and dynamic population of fringescale sardine (Sardinella fimbriata: Valenciennes, 1847) in Prigi waters Trenggalek, East Java, Indonesia

Fringescale sardine (Sardinella fimbriata) is one of important species caught in Prigi waters, Trenggalek, East Java. The existence of fringescale sardine as marine fisheries commodity plays an important role in Prigi fisheries community. This research was conducted in Prigi waters from December 2018 to July 2019 aimed to determine the biological aspects, to illustrate some dynamic population parameters, and to identify food composition. This study applied a descriptive method and random sampling for data collection. There were 1,375 fish have been assessed with total length (TL) ranging from 10 cm to 20.4 cm. Results indicated that growth patterns of the fish was negative allometric with length weight relationship equation was W = 0.014L2.804. Sex ratio of male and female obtained was 1: 1. The gonad maturity level analysis found that proportion of mature and immature fish was equal. The gonadosomatic index value was ranged from 0.57% to 2.42%. The values of length at first capture and length at first mature were 15.35 cm and 16.07 cm, respectively. The growth rate equation obtained in this study was Lt = 26.75 (1-e0.92 (t+0.178)). Mortality rates, total and fishing were 1.709 and 0.286, respectively, while the exploitation rate was 0.167. Additional assessment showed that the main food of the fringescale sardine was phylum Arthropods with index of preponderance (IP) value was 61.5%. It can be concluded that the fish was a plankton feeder and status of the stock was in over fishing condition.