In March, Tasman Bay Guardians were excited to host our second Nelson Airport volunteer session at Jenkins Creek īnanga spawning site, located on Fulton Hogan land. This site is a known īnanga (one of the 5 species of whitebait) spawning area, making it a key focus for our monitoring and restoration work.
Together with our volunteers, we carried out a saltwater wedge survey, which is an important method for understanding where īnanga are most likely to spawn. At high tide, we tested salinity levels at different points along the stream to identify where saltwater from the estuary transitions into freshwater. This transition point, known as the saltwater wedge, helps define the spawning zone, as īnanga typically lay their eggs in suitable habitat close to this area, usually within 120 metres upstream or downstream from the point.
Saltwater wedge surveys are a simple but powerful tool for monitoring estuarine systems. They allow us to track changes over time, whether from flooding events or the longer-term impacts of climate change. Encouragingly, the saltwater wedges we’ve observed across the Nelson region appear relatively stable and consistently located—but ongoing monitoring remains essential. These surveys give us an early indication of change and help guide how and where we focus community groups restoration efforts.
Understanding the location of the spawning zone means we can better target habitat protection, restoration, and planting, ensuring we’re making the biggest difference where it matters most.
It was fantastic to see volunteers getting stuck in, learning new skills, and contributing directly to the protection of our local waterways. These sessions are a great reminder of the power of community in supporting healthy ecosystems.
Looking ahead, we’re keen to build on this momentum! Exploring opportunities for future field days, spawning surveys, and planting events at the site. Watch this space!
