For years, scientists have tracked the movements of salmon through rivers in the Pacific Northwest and around the world. Now a smaller, more powerful battery will allow them to track even younger, smaller fish over longer distances. Slightly larger than grains of rice, the new batteries power a transmitter small enough to inject into these fish -- rather than surgically implant them. The result is less stressful for the fish and less costly for the researcher. Learn more about the batteries here. | Photo courtesy of PNNL.