Acanthogobius flavimanus

A. flavimanus can withstand abrupt changes between fresh and salt water and can survive temperatures greater than 28°C, therefore occupying a broad habitat range from marine to freshwater. It is an opportunistic feeder and has successfully shifted its diet from a native range to an invaded range. It negatively interacts with native and endangered species competing for food and resources (Meng et al., 1994: Lafferty et al., 1999; Nico and Fuller, 2008). It is not in IUCN Red List (Froese and Pauly, 2008).

A. flavimanus is native to China, Japan and Korea (Nico and Fuller, 2008), although it is also recorded as native to the Russian Far East (Reshetnikov et al., 1997), Vietnam (Kuronuma, 1961) and Malaysia (GBIF, 2005). It has been introduced to Australia (Victoria and New South Wales) and California, USA (Arthington and Mckenzie, 1997; Williams et al., 2001) and has now spread to Mexico (Lever, 1996) and Florida, USA (Nico and Fuller, 2008).

In Japan, it ranges from Hokkaido to Kyushu, and has been found to occur in the Himi region from a habitat study conducted in Toyama Bay (Masuda et al., 1984). In California, it has been reported from Ballona Marsh, Calaveras River, Delta-Mendota Canal, Golden Gate National Recreation area, Las Pulgas, Long Beach Harbour, Los Angeles Harbour, Los Angeles River, Malibu Lagoon, Merced, Morro Bay, Moss Landing Harbour, Mugu Lagoon, Napa, Point Reyes National Seashore, Rodeo Lagoon, Sacramento Delta, San Francisco, San Gabriel River, San Luis Reservoir, San Mateo County, San Pablo Bay, Santa Clara, Santa Margarita Lagoons, Solano County, Sonoma County, Stockton Deepwater Channel, Venice and Yolo Bypass (Nico and Fuller, 2004). In Victoria, Australia is has been reported at Corio Bay, Dights Falls, Maribymong River, Werribee River and Yarra River by Barnham (1998), and Lintermans (2004) reported its presence in Port Phillip Bay. 

A. flavimanus is a bottom dwelling fish inhabiting muddy and sandy bottoms along the shore of bays and estuaries, and sometimes ascending rivers (Froese and Pauly, 2008). Individual fish are commonly found in bays and inlets in water depths between 1 and 14 m (Barnham, 1998). However, A. flavimanus are usually found in freshwater reaches of streams just above tidal influence during most of the year, and adult fish migrate downstream to spawn in the estuaries during the breeding season in winter months.

The haploid and diploid chromosome number recorded for A. flavimanus in Japan is n=22 and 2n=44 (Arkhipchuk, 1999). A. flavimanus has been sequenced and is described in Neilson and Wilson (2005).

A. flavimanus is oviparous, spawning in winter to early spring and during the breeding season, the adults migrate downstream to spawn in the estuaries (Breder and Rosen, 1966). Fecundity ranges between 6000 and 37,000 eggs per individual (Williams et al., 1998). The eggs are constructed in intertidal mudflats and deposited in Y-shaped covered nests (burrows or tunnels), 15-35 cm deep and are ovoid (Masuda et al., 1975). The eggs measure 5.5 mm long and 0.9 mm wide and take around 28 days to hatch into free swimming larvae at optimum temperature (13°C) (Wang, 1986; Barnham, 1998; Froese and Pauly, 2005). The female may leave the burrow after spawning or may join the male in guarding the eggs (NIMPIS, 2002).   

A. flavimanus larvae are pelagic. Newly hatched larvae swim out of the burrow and remain near the bottom. The larvae remain in the water column until they reach 1.5-2.0 cm long, when they settle out of the water column (NIMPIS, 2002). After the yolk sac is absorbed, the larvae disperse rapidly. The larvae float on the surface of the water column during flood tide and descend to near the bottom while the tide ebbs (Wang, 1986). It is thought that breeding is temperature dependant, with no spawning occurring outside of 7-13°C. In Australia, reproduction occurs in winter (June-September) (NIMPIS, 2002).

A. flavimanus feeds on benthic organisms such as crustaceans, polychaetes and small teleost fish (NIMPIS, 2002). It consumes a large variety of crustaceans such as copepods, amphipods, stomatopods and mysids, and has been reported as aggressively feeding on smaller fish (Barnham, 1998). Wang (1986) reports that, major food items for small juvenile A. flavimanus are harpacticoid copepods and other copepods, whereas the large juveniles eat amphipods, mysid shrimp, and small fish.

A. flavimanus can withstand abrupt changes between fresh and salt water, and can survive temperatures greater than 28°C. They can complete their entire life cycle in fresh water, although usually at least the larval stages are spent in salt water (Moyle, 1976).

Lophius litulon (Baeck and Huh, 2003), Okamejei kenojei (Hong et al., 2000), Sillago japonica (Kwak et al., 2004), Triakis semifasciata (Talent, 1976), and Acanthogobius lactipes (Kanou et al., 2004) prey on juvenile and adult stages of A. flavimanuswhereas Lateolabrax japonicus (Kanou et al., 2004) prey on fry and juvenile stages.

There are no known predators of A. flavimanus in Australia. However, finfish and rays have been recorded as general predators of introduced populations in the USA (NIMPIS, 2002).

Animal feed, fodder, forage

• Bait/attractant

General

• Pet/aquarium trade
• Sport (hunting, shooting, fishing, racing)

Human food and beverage

• Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

A. flavimanus is sometimes confused with juvenile whiting (Sillago sp.), but can be distinguished by the fused ventral fins. It is similar in appearance to Arenigobius bifrenatus and Arenigobius frenatus, but does not have horizontal black stripes on the head that the latter two species have (NIMPIS, 2002). It can be separated from all other gobiid species in southern Australia by the combination of eight or nine spines in the first dorsal fin and the 12-14 segmented rays in the second dorsal fin (Lockett and Gomon, 1999). A. flavimanus is included in keys of Berg (1948), Miller and Lea (1972), and Moyle (1976a).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Control

Williams et al. (1998) recommend management actions that reduce off-season freshwater inflows and return tidal action to impounded saltmarsh areas in order to favour native species and prevent further spread of exotics. A. flavimanus underwent a population explosion in the San Francisco area in the late 1960s and early 1970s (Brittan et al., 1970). In 1967, a fish kill occurred in the San Luis Reservoir, which receives freshwater from the Sacramento-San Joaquin River Delta. About half of the approximately 10,000 fishes killed in this incident were A. flavimanus (Brittan et al., 1970). Apparently another massive die-off occurred in Rodeo Lagoon in 1981 and was thought to be caused by low salinity <5 ppt) (Wang, 1984).

Italy: FAO (Food and Agriculture Organization of the United Nations), Viale delle Terme di Caracalla, 00100 Rome, http://www.fao.org/

USA: United States Geological Survey, USGS National Center 12201 Sunrise Valley Drive, Reston, VA 20192, http://www.usgs.gov/

Australia: CSIRO (Commonwealth Scientific and Industrial Research Organisation), CSIRO Enquiries, Bag 10, Clayton South VIC 3169, http://www.csiro.au/

24/04/08 Original text by:

Sunil Siriwardena, Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK