Jellyfish blooms disrupt commercial fisheries around the world and blooms are increasing in frequency and magnitude in some regions (Condon, Pitt et al. 2013). Although the causes of jellyfish blooms are debated, they are frequently linked to anthropogenic pressures, including eutrophication, expansion of coastal infrastructure, and climate change (Pitt et al. 2018). The current jellyfish bloom in the Hawkesbury estuary is more extensive, persistent, and disruptive than previous blooms and may represent a long-term and sustained change to fishing conditions in the estuary. Some fishers have said they will leave the industry if blooms persist, hence this project is needed to reduce interactions between jellyfish and commercial net fishers and ensure the on-going viability of commercial net fisheries in the Hawkesbury.

The project specifically addresses the FRDC priority call for "Understanding the drivers of jellyfish blooms in the Hawkesbury". We will review the scientific literature and analyse existing data sets on water quality and jellyfish to identify probable environmental drivers of jellyfish blooms in the Hawkesbury estuary, which will enable estuary managers to prioritise which environmental conditions to manage to reduce jellyfish blooms. We will search for novel technical solutions (such as modifying fishing times or locations) that could reduce by-catch of jellyfish, assess potential ways to actively manage jellyfish (through their extraction or biological control), and co-design a long-term jellyfish monitoring program based on world best-practice with estuary managers and fishers to initiate the long-term collection of jellyfish data by stakeholders, which is essential for understanding jellyfish population dynamics and developing predictive models for jellyfish.

The drivers of jellyfish blooms in the Hawkesbury estuary may be linked to recent major floods. Floods are predicted to become more extreme and frequent under climate change. Hence our proposal aligns with FRDC's strategic investment opportunity for improving resilience of fishing in a changing climate. By providing information critical for managing jellyfish populations, our project also meets FRDC's F&D Plan Outcome 1 to "expand environmental management to cover areas other than stock status of target species". Through recruitment, mentoring and career development of a research fellow, our project builds capacity and capability of Australia's fisheries research and development sector (FRDC Enabling strategy IV).