About This Project

Regions of Bali Strait, Indonesia, have often experienced a dominant catch of Sardinella lemuru in the last decades [1,2,3], which benefits the economy & ecology aspects. However, where it went during the rising La Nina intensity in the climate change era [4] with morphological sample scarcity, this study proposes new sampling to increase eDNA recovery of S.lemuru by increasing the previous standard filtered water [11,12,18] to 3-10 L triplicate in 3 & 15 m depth without adding high field cost.

Ask the Scientists

What is the context of this research?

Bali Sardine (Sardinella lemuru) in the Bali Strait with a production volume proportion reaching 91.47% [2,6] from 1976-2006. However, due to increased sea surface temperatures, S.lemuru experienced a shortage in La Nina [3,4,10]. As a result, its status is categorized as near-threatened on the IUCN Red List and gains more significant concern regarding its sensitivity due to overfishing and environmental changes. The scarcity abundance of S.lemuru, especially in La Nina years, results in difficulties in DNA analysis, which requires morphological samples. Therefore, environmental DNA can be analyzed in depth for DNA sequences of S.lemuru to indicate their existence in seawater [11,12]. This information can be developed into a monitoring and sustainable management baseline.

What is the significance of this project?

Without proper management in Bali Strait, S.lemuru populations will be more pressured and may disappear. We are implementing eDNA as a complementary tool to map the distribution & diversity of marine species in Indonesia [10,11]. However, S.lemuru detection is poorly known with eDNA in one of its habitats [12,13]. The eDNA sampling strategies are required to ensure their distribution, regardless of their observations of morphological size [14] & catch production [3], which fluctuates temporally [4,15,16,17], even though their scarcity happened [2]. We hypothesize that recovering the eDNA of S.lemuru at a higher rate will be achieved by increasing filtered water, varying depths, & spatial distance [11,18]. This project result will be used for expanded monsoonal season monitoring & beyond.

What are the goals of the project?

Our main goal is to find S.lemuru, which is reported to have catch scarcity, so imports are needed for fish canning. We have already surveyed sites with abundant S.lemuru & sites with a declining but persistent population. We will survey 3 sites: one potential fishing site, one less potential (whether true decline or lack of fishing effort), & one site where S.lemuru scarcity was reported in 2012 [5,14,15]. Based on their vertical migration, we will filter seawater from 3-10 L triplicate at 3 & 15 m depth. Each water sample also offers other fish (i.e., substitute & invasive fish), meaning their unique DNA is revealed by eDNA. So, S.lemuru is an umbrella species symbolizing cheap & nutritious for local communities. We will publish findings & inform future decision-makers for monitoring.