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Tidewater Goby
Eucyclogobius newberryi

General Information

Official Status: Endangered, the tidewater goby is Federally listed under the Endangered Species Act of 1973, as amended in California. Critical Habitat is designated for the species, and a new proposal for critical habitat is undergoing review. A recovery plan is in effect.

Date listed: The Fish and Wildlife Service listed the tidewater goby as an endangered species under the Endangered Species Act of 1973, as amended, on March 7, 1994 (pdf, 2.7 MB)

March 13, 2014 - 12-month Finding and Proposed Rule Reclassifying the Tidewater Goby From Endangered to Threatened

Critical Habitat:

On February 6, 2013, the Service published a final rule re-designating critical habitat (pdf, 17MB)

Older Documents:

Revised Critical Habitat:

News Release: Service Proposes Revised Critical Habitat for Tidewater Goby

2011 Proposed Rule: Designation of Revised Critical Habitat for the Tidewater Goby [pdf 7.1mb]

On January 31, 2008, the Service published a final rule re-designating critical habitat (pdf, 4.0 MB) to include additional sites throughout the species' range.

Five-Year Status Review:
On September 28, 2007, the Service completed a 5-year status review (pdf, 500 KB) throughout the species' range.

Recovery Plan: Recovery plan for the tidewater goby on December 7, 2005. (pdf, 4.0 MB)

Tidewater Goby, Photo Credit: Greg Goldsmith, USFWS
Tidewater Goby

Photo Credit: Greg Goldsmith,USFWS

arrow button Photo Gallery for the Tidewater Goby

Identifying Characteristics:

The tidewater goby is a small, elongate, grey-brown fish rarely exceeding 50 millimeters (2 inches) standard length. It is characterized by large pectoral fins. The pelvic or ventral fins are joined below the chest and belly from below the gill cover back to just ahead of the anus, forming an abdominal disc. Male tidewater gobies are nearly transparent, with a mottled brownish upper surface, and generally remain near the breeding burrows. Female tidewater gobies develop darker colors, often black, on the body and dorsal and anal fins. However, the pectoral and pelvic fins, head and tail remain grey or brown. The best field mark for tidewater gobies is the transparent, whitish or yellowish triangular area on the upper 1/4 to 1/3 of the first, spinous dorsal fin. Another characteristic unique to the tidewater goby is that the upper end of the gill opening stops a few fin rays below the upper end of the pectoral fin base.

Current Geographic Range:

The tidewater goby, a fish species endemic to California, is found primarily in waters of coastal lagoons, estuaries, and marshes. Tidewater gobies live only in California, and historically ranged from Tillas Slough (mouth of the Smith River, Del Norte County) to Agua Hedionda Lagoon (northern San Diego County). They currently are found throughout their known, historic range, but reside at fewer locations than historically occurred, having been extirpated from some sites as a result of drainage, water quality changes, introduced predators, and drought. The tidewater goby is thought to have occurred in as many as 124 different locations during recent decades, but currently can be found in only about 96 of those historic locations, and only about 54 of those 124 populations are thought to be secure at this time. Tidewater gobies can recolonize habitats when favorable habitat conditions are restored and individuals repopulate this restored habitat, either through natural dispersal or through human-assisted reintroduction. Tidewater gobies are naturally absent from areas where the coastline is steep and streams do not form lagoons or estuaries. Several large, natural gaps occur in the species’ distribution from northern Sonoma County to Del Norte County, where steep rocky shorelines dominate the coastline, and salt marsh and stream estuaries do not naturally occur.

Life History:

The tidewater goby is typically an annual species (that is, it typically lives for only about 1 year), although some variation has been documented. Tidewater gobies may occur in loose aggregations of a few to several hundreds or thousands of individuals.

Reproduction occurs nearly year-round, especially in warmer waters in the southern portion of the species’ range. Distinct peaks in spawning may occur in spring and late summer. Peak breeding activities commence in late April through early May, when male gobies dig a vertical nesting burrow 10 to 20 centimeters deep in substrate that usually contains a coarse sand component. Female tidewater gobies lay 300 to 500 eggs, which adhere to the walls of the burrow until hatching. Male gobies remain in or near the burrows for approximately 9 to 11 days to guard the eggs until they hatch. Once the eggs hatch, larval gobies are pelagic, and stay in the mid-water column near underwater vegetation until they become benthic. Although the potential for year-round spawning exists, it is probably infrequent because of seasonal low temperatures and disruptions of lagoons during winter storms. Ecological studies performed at two sites documented spawning occurring as early as the first week in January.

General Habitat Characteristics:

The species is benthic in nature, living at the bottom of shallow bodies of water. Its habitat is characterized by brackish (somewhat salty) water in shallow lagoons and in lower stream reaches where the water is fairly still but not stagnant. The tidewater goby, the only species in the genus Eucyclogobius, is mostly restricted to waters with low to moderate salinities in California's coastal wetland habitats. All life stages of the tidewater goby typically are found in lagoons in areas of low to moderate salinity (commonly less than 12 parts per thousand [ppt], but at times and at some locations may be hypersaline). Tidewater gobies have been documented in waters with salinity levels from 0 to 42 ppt or higher (as a comparison, sea water is about 34 ppt), temperature levels from 8 to 25 degrees Celsius (46 to 77 degrees Fahrenheit), and water depths from 25 to 200 centimeters (10 to 79 inches). Tidewater gobies prefer a sandy substrate for breeding, but they can be found on rocky, mud, and silt substrates as well. Recent information suggests that gobies can occur in water up to 4.6 meters (15 feet) in depth in large lagoons, and may have a wide tolerance for salinity, oxygenation, and temperature, especially over short time periods or seasonally.

Vegetation within tidewater goby habitat generally is sparse, consisting of several species of submerged or emergent aquatic plants, including widgeongrass (Ruppia maritima), bullrushes (Scirpus sp.), and pondweed (Potamogeton sp.). Gobies may use the edges of dense patches of vegetation, where they escape predation if disturbed. Actual breeding sites, though, may be in mostly open, unvegetated sand or silt substrates, and not within dense vegetation.

Like estuarine habitats in general, tidewater goby habitat is subject to fluctuation of physical factors on both a daily and a seasonal basis. The lagoonal nature of many habitats tends to dampen short-term variation, but annual variation can be considerable. Winter rains and subsequent increased stream flows usually cause considerable flooding, breaching, and washing out of lagoonal waters, reducing salinity levels to near fresh water conditions. During drier seasons, these habitats again reach a dynamic stability of depth and salinity, conditions favorable to goby reproduction.

The tidewater goby appears to spend all life stages in lagoons, estuaries, and salt marshes where brackish water conditions occur. Adult tidewater gobies may enter marine environments when flushed out of their preferred estuarine habitats by seasonal breaching of the sandbars following storm events, but may not survive for long periods in the marine environment. Pelagic juvenile gobies may be flushed from natal estuaries and lagoons in those locations where daily interchange of water occurs with the marine environment. However, these may be natural mechanisms of dispersal between suitable habitats on a local basis, where conditions are favorable to retain a sufficiently robust breeding population in the natal site. Gobies are unlikely to persist where daily tidal fluctuations cause substantial portions of the breeding population to be flushed from natal sites on a regular basis, or where tidal fluctuations cause breeding substrates to be dewatered. Although usually associated with lagoons and estuaries, the tidewater goby has been documented in slack freshwater habitats as far as 5 miles upstream from San Antonio lagoon in Santa Barbara County.

Population and Habitat Status:

Tidewater gobies currently occur along the coast of Mendocino, Humboldt and Del Norte Counties at several locations. A large population occurs in Lake Tolowa/Lake Earl, with smaller populations occurring in Stone Lagoon and Big Lagoon. Other locations where tidewater gobies have been observed during the past decade include Tillas Slough (Del Norte County), Jacoby Creek, Gannon Slough and Mad River Slough in Humboldt Bay, the Eel River delta, and Tenmile River, Pudding Creek, and Davis Creek in Mendocino County. Other populations may exist along the north coast, although surveys conducted during 2003 and 2004 found few new occupied sites. Most of the known populations have likely been significantly reduced from historic levels. The species is likely extirpated from at least two historic sites in the north coast region (Freshwater Lagoon and Redwood Creek estuary) as a result of human alteration of water flows and (at Freshwater Lagoon) the introduction of predatory fishes. Other extirpations are likely to have occurred around Humboldt Bay, where extensive estuarine habitats occurred prior to major drainage and diking around the bay during past decades. Current and future habitat restoration projects around Humboldt Bay place increasing emphasis on the tidewater goby as an essential component of the assemblage of fish species to be recovered in estuarine and lagoonal habitats in the area.


The tidewater goby is threatened by modification and loss of habitat resulting from coastal development, channelization of streams and estuaries, diversions of water flows, groundwater over drafting, and alteration of water flows. Potential threats also include discharge of agricultural and sewage effluents, increased sedimentation from improper agricultural activities, unnatural breaching of estuaries and lagoons, upstream alteration of natural sediment flows, introduction of predatory fishes and plants, direct habitat damage, and watercourse contamination resulting from vehicular activity in the vicinity of lagoons.

The brackish zone, preferred by the tidewater goby, is often modified or eliminated by human-created barriers such as dikes and levees, typically at the upstream terminus of channelization. These barriers are typically built to provide flood protection to farm or grazing land, residential or commercial development. Coastal developments that modify or destroy coastal brackish-water habitat are the major factor adversely affecting the tidewater goby. Coastal lagoons and marshes have been drained and reclaimed for agricultural, residential, and industrial developments. Waterways have been dredged for navigation and harbors, resulting in direct losses of wetland habitats as well as indirect losses due to associated changes in salinity. Coastal road and railroad construction have severed the connection between marshes and the ocean, resulting in unnatural water temperature and salinity profiles.

Upstream water diversions adversely affect the tidewater goby by altering downstream flows, thereby diminishing the extent of habitats that occurred historically at the mouths of many rivers and creeks in California. Alterations of flows upstream of coastal lagoons have already changed the distribution of downstream salinity regimes. Upstream water diversions may change the salinity distribution in estuaries and lagoons, and may reduce the size and distribution of goby populations.

The accidental and purposeful introduction of native or non-native species, particularly predatory fishes and amphibians, has been responsible for drastic reductions in populations of tidewater gobies at some sites. The introduction of other non-native species that may compete with tidewater gobies is another cause of decline.

Conservation Needs:

The long-term persistence of the tidewater goby requires protection and, in some cases, restoration of its suitable habitat. In certain localities, particularly in southern California, restoration of degraded habitat (e.g., removal of fill, reestablishment of natural semi-open connections between lagoon and ocean) will be necessary for establishment of viable metapopulations. In some locations, reintroduction of tidewater gobies to formerly occupied habitat, or restoration of natural dispersal mechanisms and pathway, may be necessary to establish viable populations where they have been extirpated in the past. Removal of fill material, including the relocation or removal of levees used to drain former salt marsh and other suitable habitat, may be considered on a site-by-site basis to reestablish extirpated populations, or restore connectivity within fragmented habitats supporting historically interconnected metapopulations. Coastal developments should consider the habitat needs of the tidewater goby when they have the potential to change or affect coastal hydrologic patterns, where they may contribute pollutants to the aquatic environment, or where they may require filling of suitable goby habitat. Exotic species that prey upon or compete with tidewater gobies may require control, on a local or regional scale, where they have the potential eliminate gobies, or where they may preclude successful reestablishment of tidewater gobies within their historic habitat. Restoration projects, especially those designed to restore or enhance other resource values, should carefully consider the needs of tidewater gobies where they occur, or where reestablishment of tidewater goby populations is an important recovery objective.

Related Documents:
Other Informational Weblinks:


Last updated: July 25, 2014

Arcata Fish and Wildlife Office, 1655 Heindon Road, Arcata, California 95521, USA
Tel: (707) 822.7201 Fax: (707) 822.8411