Eucyclogobius newberryi (Fishes)
The Tidewater Goby is a small fish, rarely longer than two inches, with large pectoral fins. Male Tidewater Gobies are nearly transparent, while females develop darker colors, often black, on their body and dorsal fins. They generally live for only one year, and feed mainly on insect larvae and small crustaceans. In turn they are prey for larger fish and aquatic birds.
The Tidewater Goby is a California endemic, which means it is only found within the State of California. Despite extensive searches, it has never been found in either Oregon or Mexico. Within California, it is usually found in coastal lagoons. These lagoons are formed when sand bars trap water from streams near the ocean, creating a pool of cool, brackish (partly salty) water.
Although the Tidewater Goby is most at home in shallow, brackish waters, it is frequently found several miles into fresh water streams and can withstand short periods in ocean water. However, if salinity stays high for too long, either because of ocean floods or the diversion of freshwater inputs, the Tidewater Goby cannot survive.
Tidewater Gobies usually breed in waters with a sandy bottom. Males dig breeding burrows in around April or May, and then hide in these burrows while females aggressively spar with each other for access to the males with the best burrows. After breeding, the males care for the embryos night and day until they hatch, which can take 9-11 days. During this time the males emerge from the burrows rarely, usually to feed.
Although they are frequently the most abundant fish species in a given location, the Tidewater Goby’s population fluctuates greatly; for example, the species endured dramatic population decline after the prolonged drought of the late 1980s and early 1990s. This fluctuating population dynamic puts the species at risk of extinction when their populations become small, because the species might fluctuate to zero.
Today Tidewater Gobies are adversely affected by development projects that modify or destroy their coastal habitat; by stream diversions that remove water from their habitats; and the digging of channels in lagoons and streams where they live. They are also threatened by the introduction of exotic fish species. For example, presence of tule and Sacramento perch has probably prevented tidewater gobies from inhabiting the San Francisco Bay delta, an otherwise ideal habitat.
The tidewater goby is known to have inhabited at least 134 localities; as few as 41 of these locations have viable populations today. It is no longer found in San Francisco, and is extirpated from San Francisco Bay. Because of this decline and the ongoing threats to the species, the Tidewater Goby was protected as an endangered species under the federal Endangered Species Act in 1994.
Nonetheless, Tidewater Gobies are found in several locations in the Bay Area, including Rodeo Lagoon within the Golden Gate National Parks, as well as Lagunitas Creek and a large area of the Pescadero Marsh Natural Preserve.
Conservation Action Item
Monitor invasive aquatic species:
Learn to identify them and report sightings
Tidewater gobies are vulnerable to introduced fish predators and competitors. Unfortunately, introductions of nonnative species are on the increase today for sport, bait, commercial, and aquaculture purposes. In San Francisco Bay, two million gallons of ballast water from large ships containing potential invasive species are released every hour. Help control the number of invasive, non-native species introduced into the Tidewater Goby’s GGNP habitats by learning how to identify San Francisco Bay’s worst invasive species and reporting sightings to the Aquatic Nuisance Hotline online or by calling 877-STOP-ANS (786-7267).
Big Year Competitors have reported 0 sightings and taken 0 actions to help this species recover so far this year.
- None scheduled
Log in to participate in Big Year!