This past weekend I headed up to Napa Valley looking for spawning aggregations of lampreys. River lamprey (Lampetra ayersii) are kind of spotty around here, and a couple streams trib to San Pablo Bay seemed to offer the best chance of seeing one, however, most of the streams are closed to fishing right now (T&E steelhead runs), and most of the watershed is heavily posted (No trespassing. Keep out. This means you, etc.). It took me the better portion of the day to find a decent access point, and I finally suited up in a supermarket parking lot, crossed a highway and hit the water. As you might expect given the number of wineries and intense agriculture in the valley, there were heavy algal mats carpeting the substrate, and water clarity was not particularly great. I'm sure it was a veritable stew of pesticides (gee, wonder why the steelhead aren't doing so well?!).

Where I started was tidally influenced, and each rock had a goby underneath (unsure of the species, didn't retain any or take pics). The goby/sculpin ratio got better as I headed upstream, all prickly sculpins, Cottus asper. Signal crayfish (Pacifastacus leniusculus) were moderately abundant, some were remarkably large. Few larger fish, only a handful of Sacramento sucker (Catostomus occidentalis). One single, small, deeper-bodied fish that streaked past too fast to ID, possibly a tule perch (Hysterocarpus traskii). No salmonids, not even juveniles. After a couple hours of unsucessfully lifting every large rock I could find, I found a large log lying in fast current. As I lifted it, I saw a river lamprey about 20 cm long shoot upstream and away - but no doubt on the ID, it had a huge eye and silvery blue dorsum. I got a good look at it, but was unable to drop the log fast enough to catch it, and didn't see another. After snorkeling about 1.5 km of stream, I turned around and headed back, and as I swam through a deeper pool a largish Pacific lamprey (Lampetra tridentata) was lying on the bottom, obviously near death. After hauling it ashore, I realized why - it was bleeding from a large puncture wound on its back, but whether it was from an osprey talon or some kid with a spear I couldn't tell. Still, a pretty remarkable animal, and beautiful in its own special way. It rained much of the day, so pics aren't optimal.

I may go back sometime in the next couple of weeks to try again, possibly further upstream. I'd really like to get good photos of L. ayersii. Lamprey redds should be visible from the bank, so it's just a matter of finding access, covering ground, and getting lucky...

Wish you better luck on the L. ayersii next time.
Still that is one very nice looking L. tridentata. Have you ever run across any of the Landlocked "Tridentata" ?