Understanding wedgefish reproduction for conservation in Jepara, Indonesia

The project titled “Understanding the Reproductive Strategy of the Critically Endangered Bottlenose Wedgefish in Indonesia for Future Species-Specific Conservation Planning” officially kicked-off with an online meeting held on 16 January 2025. This project will be conducted at Jepara, Central Java, Indonesia. This collaborative initiative involves the Diponegoro Biodiversity Project (DBP), Biology Department, Diponegoro University, and the Elasmobranch Project Indonesia (EPI].

The primary objective of the project is to investigate the reproductive strategy of the bottlenose wedgefish (Rhynchobatus australiae), a Critically Endangered species. By utilising genetic population analysis, we aim to determine patterns of paternity and assess whether the species exhibits monogamy or polyandry behaviour in the Karimunjawa National Park (KJNP), Jepara and adjacent waters. To achieve this, we will use microsatellite DNA analysis to examine patterns of paternity and gain insights into the species’ reproductive dynamics, which are essential for guiding future conservation efforts in Indonesia.

Online meeting held between representatives of the Diponegoro Biodiversity Project (DBP) team and the Elasmobranch Project Indonesia (EPI) team. Photo © DBP team

During the meeting, representatives from all participating institutions gathered to align on the project’s master plan. Key topics included a review of existing and prospective sample data contributed by the EPI team, the conceptualisation of laboratory workflows, and the establishment of standardised procedures for data analysis. The discussion also addressed timelines, roles, and anticipated challenges.

Enumerators from the Elasmobranch Project Indonesia (EPI) conducted length measurements of Rhynchobatus specimens. Photo © EPI team

A focal point of the meeting was the utilisation of tissue samples collected by EPI. These samples will be used to conduct DNA barcoding to confirm the species’ identity of Rhynchobatus australiae. Upon successful confirmation, microsatellite analysis will be conducted to investigate the paternity condition from the location target.

Enumerators from the Elasmobranch Project Indonesia (EPI) performed weight measurements and pup sampling in Demaan Village, Jepara. Photo © EPI team

From the project’s initiation until June 2025, enumerators from EPI conducted sampling activities in Demaan Village, Jepara. Biological samples were collected in collaboration with local fishers, who landed specimens at the village’s coastal site during routine fishing operations. Between March and June 2025, DNA barcoding was performed on 65 samples, including both adults and pups, to verify species identity and confirm whether the specimens belonged to R. australiae.  Once the species was verified, the next step was to understand how these fish reproduce. From July to August 2025, we will plan to use microsatellite analysis. This analysis will help us to figure out whether the pups come from one father (monogamy) or multiple fathers (polyandry).

The Diponegoro Biodiversity Project (DBP) team (Eka Maya Kurniasih and Nining Nursalim) conducted laboratory activity for DNA barcoding and trial runs of microsatellite analysis. Photo © DBP team

A member of the Diponegoro Biodiversity Project (DBP) team conducting laboratory work for DNA barcoding and trial runs of microsatellite analysis. Photo © DBP team