Making Backpacks for Tiny Fish

A rice-sized tracking device is revolutionizing what scientists know about the smallest creatures in our waters. For the endangered delta smelt, a slender 2.5-inch fish that once thrived in California's Sacramento-San Joaquin Delta, this technology couldn't come soon enough.

"We need to know things like, Where are they going? How do they get there? We don't even know where they spawn," explains Eric Chapman, a fish biologist working to track these vanishing fish.

Traditional underwater tracking devices, too heavy for tiny species, have left vast portions of aquatic ecosystems unstudied. But researchers at the Pacific Northwest National Laboratory have developed micro-battery powered tags weighing less than the eraser on a pencil.

Despite their minuscule size, these experimental trackers can transmit signals for nearly 40 days and hundreds of meters through water – a remarkable achievement given water's tendency to weaken radio signals.

Scientists hope to deploy these tags on delta smelt by 2026, potentially revealing crucial information about their movements and breeding grounds. This breakthrough could transform conservation efforts not just for smelt, but for countless small species that form the foundation of underwater ecosystems across North America.