Did you know that lamprey live in the San Lorenzo River? Here is your proof! We received these incredible shots of a Great Blue Heron eating a Pacific lamprey at the San Lorenzo River mouth on June 7, 2024, from Alan Ritch, Associate University Librarian Emeritus from UC Berkeley. Alan was exploring the river estuary with his granddaughter when they noticed a Great Blue Heron hunting in the water. To their surprise, it successfully captured (and ate!) a large adult lamprey!
Great Blue Herons are known for their patient hunting skills, standing motionless until they are ready to strike. They use this approach to catch a wide variety of prey. Fish are a major part of their diet, but they can also eat frogs, salamanders, turtles, snakes, insects, rodents, and birds. You might see one stalking a vole or gopher on a lawn, and they can even eat waterbirds. This adaptability is one reason they are widespread, and can be found across the entire continental United States, as well as into Canada and Mexico.
Pacific lamprey used to be abundant in the San Lorenzo River, but now sightings are quite rare. Like salmon and steelhead, lamprey are anadromous, meaning they are born in freshwater, migrate to the ocean as adults, and return to freshwater to spawn. They belong to one of the most ancient families of jawless fishes, and use their sucker-like mouths to latch on and parasitize other fish. Lamprey also have important cultural value for Native American tribes like the Ohlone. Learn more about these fascinating fish in our blog post here!
The San Lorenzo River’s wildlife is pretty amazing! This sighting just goes to show you never know what you might find when you spend time by the river.