To facilitate the return of steelhead trout, the National Park Service has been working with many partners including the City of Malibu and CalTrans to restore Solstice Creek, one of the few streams in the Santa Monica Mountains with year-round flow, by refurbishing and building bridges, removing old dams and stream crossings, and weeding and replanting native vegetation in the area.
Southern Steelhead Trout
Southern steelhead trout are a federally endangered species. Depending upon where they mature, the same species will develop into one of two radically different adult forms — rainbow trout (freshwater) or Southern steelhead trout (ocean water). The Resource Conservation District conducts a monthly survey led by its Senior Conservation Biologist.
Arroyo chub, a California Department of Fish and Wildlife Species of Special Concern, occur in Topanga Creek and Malibu Creek. Most adults are 7–10 cm in length with a maximum length of 12 cm. Colors range from silver to green to grey, with white on the bottom and a gray stripe on the side. While they will eat insects and crustaceans, they are partial to algae.
In the late spring and early summer on certain moonlight nights, the shores sometimes swarm with incoming grunion, beautiful little silver fish that mate in a spectacular orgy. Females dig themselves into wet sand to lay eggs while eager male suitors pile around to contribute smelt. Leaving the fertilized eggs undisturbed in the sand for the weeks it takes for the baby fish to develop is vital to the survival of the next generation of grunion.
Grunions are protected by a closed collection season during their peak spawning period April through May. Join the Grunion Greeters and help count the fish, along with scores of citizen scientists. There is a grunion program offered to the public at Cabrillo Beach in San Pedro on several nights of the season. Call 310-548-7562 for details.
Dr. Karen Martin, Pepperdine University’s Professor of Biology, collaborates with beach maintenance professionals in the Beach Ecology Coalition to ensure that public beach grooming does not jeopardize grunion populations.
Carp, sunfish, bass, bluegill – the full list of invasive fish species in the Santa Monica Mountains is as long as movie credits for a science film. Why is this a problem? The propensity of these fish to eat young Southern steelhead trout is a limiting factor to their full recovery. Under no circumstances should fish be released in Southern California streams.
Crayfish, a freshwater species which look like tiny lobsters, come from Louisiana where other aquatic species have eadapted to handle these fierce predators. In the Santa Monica Mountains, there are no aquatic predators to keep the population down, so despite a few hunting forays by raccoons and birds, and some crayfish removal efforts, the number of crayfish in the Malibu Creek Watershed is enormous – and they feed on young Southern steelhead trout. Under no circumstances should crayfish be released in any California streams.
New Zealand Mud Snails
New Zealand Mud Snails are tiny – ranging from the size of a flea to a grain of rice. Having no local predators they have spread widely in many – but not all – creeks in the Santa Monica Mountains. Steelhead trout eat them but cannot digest them, making them the empty calories of our riparian ecosystems. For younger fish, eating food that does not nourish can be catastrophic so we aim to reduce their spread by practicing safe creek visiting.