Semi-natural Spawning of the Hal Semi-natural Spawning of the Halmahera Walking Shark (Hemiscyllium halmahera) at UPTD Perikanan Unggulan Morotai

Abstract

This study aimed to examine the semi-natural spawning process of the Halmahera walking shark (Hemiscyllium halmahera), an Indonesian endemic species of high conservation value. The research was conducted at the UPTD Perikanan Unggulan Morotai from July to September 2025 using a field-based quantitative experimental approach. Four broodstock (three females and one male) collected from the wild were maintained in a 3,500-liter semi-natural tank designed to simulate natural habitats with coral and gravel substrates. Water quality parameters—temperature, pH, salinity, and ammonia—were measured every three days to identify their influence on reproductive activity. The findings revealed that temperature (r = 0.97; p < 0.01) and salinity (r = 0.88; p < 0.05) were the most influential environmental factors triggering spawning, while pH and ammonia had secondary roles. During the 90-day observation period, two spawning events occurred, producing two pairs of egg capsules with typical morphology, although no embryonic development was detected. The study demonstrates that a semi-natural system can effectively stimulate natural reproductive behavior in H. halmahera and provides a scientific foundation for hatchery-based conservation of endemic elasmobranch species in Indonesia. Future studies with extended observation periods and hormonal stimulation are recommended to enhance fertilization success.