What: About 7,500 juvenile chinook salmon and 375 steelhead will be "photonically" tagged by high-school students in the first large-scale application of this technique in California. Members of the UC Davis Bodega Marine Laboratory and New West Technologies will also be participating. This effort begins field testing of a new "light-triggered" tag that is easy to apply and to read and is economical. "Ultimate success of the photonic tag could revolutionize the way we manage all our hatchery-produced fish so they do not compete with wild fish stocks," says Paul Siri, assistant director of the Bodega Marine Laboratory. This work is part of the laboratory's ongoing research on the salmon runs in California, which includes maintaining broodstocks and following the population genetics of declining runs. When: Monday, May 15 11 a.m. to 6 p.m. Where: United Anglers Conservation Hatchery at Casa Grande High School Petaluma Visuals: At the state-of-the-art hatchery, fish will be anesthetized by Bodega Marine Laboratory researchers and then tagged by students. The photonic tag, a solution of latex beads that contain dyes reactive to high-energy light sources, will be shot into the fins of the fish using specially adapted vaccination guns. Bodega researchers, New West staff and the students' instructor, Tom Furrer, will be on hand to answer questions. Directions: From Highway 101 north to Petaluma take the Lakeville Highway exit. Turn left on Lakeville. Go to the third light and turn left on Casa Grande. Continue past the high school entrance to Ely Road. Turn left on Ely and the hatchery facility entrance is in the first parking lot on the left. Map available upon request.