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The Santa Monica Bay (SMB) is home to some notable endangered fish, one of which is the remarkably adorable tidewater goby (E. newberryi). This visually charming fish inhabits lagoons along the coast of the Santa Monica Mountains, and the RCD has been carrying out population dynamic studies for years. In our most recent study, we discovered an interesting phenomenon amongst this local population: while populations of endangered tidewater goby remain variable in Big Sycamore and Malibu lagoons, the population in Topanga lagoon appears quite stable. This interesting phenomenon has led our Research and Restoration team to question why this could be happening. How different are these Santa Monica Mountain creeks and lagoons? What kind of habitat does this goby prefer and could the answer to this question help us better protect and preserve this endangered fish? Given the pending restoration of both Topanga and Big Sycamore lagoons, these questions become undeniably imperative to answer.

Tidewater goby are small, elongate, grey-brown fish only about 2 inches in length. They are characterized by large pectoral fins and joined pelvic fins below the chest forming an abdominal disc, almost like a little foot. Tidewater gobies live only in California, and historically were found along almost the entire coast. In 1994 they were listed as federally endangered and though they are still found throughout their historic range, they have been observed at far fewer locations, having been extirpated from some sites altogether as a result of drainage, water quality changes, introduced predators, and drought.

With funding from California Department of Parks and Recreation, the RCD coordinated late fall tidewater goby surveys at lagoons in Big Sycamore, Malibu and Topanga, which comprise some of the best possible habitats for this species in the SMB while also being some of the most impacted regions in the state. Conducting surveys at this time of year allows us to document the abundance and distribution of these fish during closed lagoon conditions (i.e. times of the year when lagoons are disconnected from the ocean), though Malibu Lagoon unexpectedly breached following a full moon in August.

While no tidewater gobies were observed in Big Sycamore or Malibu, in Topanga many tidewater gobies were surveyed. Next steps for this important conservation work include DNA and stomach content analysis. DNA analysis will be carried out by Dr. David Jacobs of UCLA when funding is available and will help us understand the relatedness of various populations throughout the Santa Monica Mountains. Stomach content analysis will be done with help from students at Cal State University Channel Islands and will help clarify food resources and preferences. We will also be analyzing sediment cores and benthic macroinvertebrate community conditions as part of a larger effort to characterize preferred habitat for tidewater gobies.

The RCD expects to continue these surveys when lagoons are opened (i.e. connected to the ocean) in spring 2021 which will allow us to compare population dynamics during closed and opened conditions. We hope our monitoring efforts will provide information to scientists to help this endangered species recover and recolonize lost habitat. Stay up-to-date on this project and projects like it by subscribing to our newsletter and following us on social media.