High catch of Sardinella lemuru (Bleeker, 1853) and plankton abundance in Prigi Waters: Case study in 2017 and 2019

Prigi Waters, East Java, is known as a fishing ground for mackerel tuna and other tunas. However, at the end of 2019, it was found that Bali Sardine (Sardinella lemuru) was a dominant caught that reach more than 56% of the total catch. The reason for the high fish abundance in 2019 is still unknown. Therefore, this study aims to understand the relationship between S. lemuru catch and plankton abundance in Prigi Waters during the high catch event and comparing a similar study in 2017. Plankton abundance was analyzed using the APHA method. Pearson correlation analysis was used to express the relationship between S. lemuru catch and plankton abundance. The result showed that the composition of zooplankton and phytoplankton in waters was 52.8:47.2. Class Bacillariophyceae dominated the phytoplankton group in Prigi waters (47%), where Actinocyclus is the most common genus found (28,762 cell/m³). While in the zooplankton group, the class Maxillopoda dominated (75%), where Nauplius is the most common genus found (34,876 ind./m³). The Pearson correlation analysis showed that S. lemuru catch in November 2019 was greatly influenced by phytoplankton (61.32%) than zooplankton (21.38%) abundances, and the rest was influenced by other factors. High and low plankton abundance in 2019 and 2017 has implications to high and low catch of S.lemuru, respectively. It is suggested that routine and continuous monitoring of plankton may provide good information for fisheries prediction and management in Prigi Waters.