Eucyclogobius newberryi (Fishes)

Species Description

The Tidewater Goby is a small fish, nearly unique among fish of the Pacific coast in being restricted to partly salty coastal lagoons and estuaries. First described as a species in 1856, its historical range is from three miles south of the California-Oregon border to forty-four miles north of the United States–Mexico border. In spite of extensive searches, it has never been found in either Oregon or Mexico. The tidewater goby is known to have inhabited at least 134 localities; as few as 41 of these locations are currently securely populated.

The fish are rarely longer than two inches, with large pectoral fins. Male Tidewater Gobies are nearly transparent, while females develop darker colors, often black, on the body and dorsal fins. The species is typically found in water less than three feet deep, most often breeding in sandy regions. Males begin digging breeding burrows in April or May; females then aggressively spar with each other for access to males with burrows. This female-dominant breeding system is rare among vertebrates and very uncommon among gobies. The males care for the embryos for nine to eleven days until they hatch, rarely if ever emerging from the burrows to feed.

Tidewater Gobies generally live for a single year. Although they are frequently the most abundant fish species in a given location, the population fluctuates greatly; a dramatic decline in their numbers occurred after the prolonged drought of the late 1980s and early 1990s. They are adversely affected by coastal development projects that modify or destroy their coastal habitat, and by stream diversions and the digging of channels in lagoons and their tributary streams.

They feed mainly on insect larvae and small crustaceans, and in turn are prey to larger fish and aquatic birds; they are threatened by the introduction of exotic fish species. The presence of tule and Sacramento perch has probably prevented tidewater gobies from inhabiting the San Francisco Bay delta, an otherwise ideal habitat. Although they are most at home in partly salty waters, they are frequently found several miles into fresh water streams and can withstand short periods in ocean water.

Tidewater Gobies are found in several locations in the Bay Area, including Rodeo Lagoon within the GGNP, as well as Lagunitas Creek and a large area of the Pescadero Marsh Natural Preserve. Although no locations in San Francisco currently support the species, specimens collected in 1874 at the Cliff House Restaurant are in the Natural History Museum of Vienna, Austria; in 1895, specimens were collected at Lake Merced.

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: 877-STOP-ANS (786-7267).

Big Year Competitors have reported 2 sightings and taken 2 actions to help this species recover so far this year.

Trips

• Go-Go Gobies! CANCELED
  Saturday, 22 May 2010, 10:00 - 12:00 Pacific Time (US & Canada)