REPRINT FROM CALIFORNIA FISH and GAME "CONSERVATION OF WILDLIFE THROUGH EDUCATION" VOLUME 49 OCTOBER 1963 NUMBER 4 AN ORIENTAL GOBY COLLECTED IN THE SAN JOAQUIN RIVER DELTA NEAR STOCKTON, CALIFORNIA The California Department of Fish and Game has recently collected two specimens of a goby previously unknown in Californian waters. These we have identified as a species common in Japan, China, and Korea, Acanthogobius flavimanus ( Temminck and Schlegel), often re- ferred to as A. flavimanus (Schlegel). The first specimen was taken on January 18, 1963, by Arnold B. Albrecht and Vincent A. Catania (personnel of the Dingell-Johnson Project California F9R, "A Study of Sturgeon and Striped Bass," supported by Federal Aid to Fish Restoration funds), in a midwater trawl in the San Joaquin River off Prisoners Point on the southwest shore of Venice Island. Salinity here is very low, under 30 ppm (chlorides) at this time of year. The second specimen was collected in an otter trawl on March 29, 1963, by E. G. Gunderson, Armand P. Croft, Jr., and Vincent A. Catania, in the Stockton Deepwater Channel just above the entrance of the Calaveras River and just downstream from Port of Stockton. Although approxi- mately 12 miles above the first station, salinity here is slightly greater, measuring about 70 ppm (chlorides) at this period in the year. The first goby was 123 mm standard length (155 mm total length) ; the second was 69 mm s 1 (85 mm t.1.). Both have been deposited at Sacramento State College (SSC nos. 35-1 & 36-1). They exhibit close agreement with examples of A. flavimanus in the Stanford University Division of Systematic Biology (SU nos. 6574, from Tsuruga, Japan, and 6581, from Nagasaki, Japan) and with the descriptions and illus- trations in Temminck and Schlegel (1845, p. 141, pl. 74, fig. 1), Jordan and Snyder (1901, p. 98), and Okada (1961, p. 671, fig. 114). This species can be distinguished easily from any of the native Cali- fornian gobies by the following combination of characteristics : 8 spines and 14 soft rays in the dorsal fin ; 46-56 scales in the midlateral series, starting at the upper limit of the opercular opening ; about eight diffuse dusky spots, each somewhat larger than the eye-diameter, arranged in a nearly evenly-spaced series down each side, the first three being concealed beneath the pectoral fin, the last forming a more prominent spot at the base of the caudal fin ; the sides and back being indistinctly mottled ; the upper two-thirds of the caudal fin with about 10 narrow, vertical, dusky, zigzag bands, the lower third plain dusky. It also grows larger than any Californian species except the mudsucker, Gillichthys mirabilis, and the longtail goby, Gobionellus longicaudus; all three reach about 8 inches. ( 302 ) NOTES 303 FIGURE 1. Oriental goby, Acanthogobius flavimanus (Temminck and Schlegel), 123 mm standard length, taken in the San Joaquin River at Prisoners Point, Venice Island, San Joaquin County, by A. B. Albrecht and Vincent A. Catania. Drawings by Martin R. Brittan. As both our specimens are small, it appears possible that a local breeding population may be getting established. In its native waters, A. flavimanus is widely distributed in estuarine environments, ascend- ing a short distance into streams and lakes near sea-level. The Delta region of California appears to be similar to many Oriental estuaries. Okada (1961, pp. 672-3) states under ''Habits": " The present species may mature after one year. The breeding season occurs in February and March. The eggs are deposited under sand or muddy bottom of shallow water. The adults live mostly in brackish water around mouths of rivers and sometimes enter into lakes and swamps along seacoasts, and also into rivers. Young live in the mouths of rivers making groups [aggregating] and when the temperature goes down at the end of autumn, they descend into the sea. Foods [presumably of the adults] are small fishes and crustaceans." He also reports on the work of Dotu and Mito (1955) on the breeding habits : "The spawning season extends from January to March in Kyushu. The breeding room, some- what flat and Y-shaped, with two entrances, is made vertically in the tidal flat deposit. Eggs are club-shaped, 5.5 mm x 0.95 mm in size, with adhesive filaments around the basal end, attached to the wall of the upper part of the room. The incubation period extends about 28 days under the water temperature of 13°C. The newly hatched larva is about 4.6 mm in total length. The larvae, 4.9-12.00 mm in size, spend a pelagic life in the bay, while the young of 15-20 mm in size move to bottom of estuaries. The food is mostly consisting of planktonic copepods." Okada's plate 62 (after Dotu and Mito, 1955) illustrates the embryonic and larval development. We do not know how A. flavimanus was introduced into the Delta, but it is interesting to note than an Oriental shrimp, Palaemon macro- dactylus ( Rathbun), was introduced into the San Francisco Bay area, apparently around 1954, and now is contributing substantially to the commercial shrimp catch (Newman, 1963). The mechanism of this introduction is also unknown, but was probably accidental. New- man (1963, pp. 128-9) feels Palaemon larvae may have been carried in a ship 's sea water system which was partially clogged with fouling organisms, such as tubeworms and barnacles. A. flavimanus could have been introduced in a similar manner. 304 CALIFORNIA FISH AND GAME In view of the eurythermal and euryhaline characteristics of the Gobiidae, and this region's resemblance to many estuarine complexes in the Orient, A. flavimanus may establish a substantial population throughout the Sacramento-San Joaquin Delta and San Francisco Bay region. It is possible, also, that A. flavimanus may be utilized as a bait fish, as are mudsuckers in southern California. REFERENCES Dotu, Y., and S. Mito 1955. On the breeding habits, larvae, and young of a goby, Acanthogobius flavi- mantis (Temminck et Schlegel). Japan Jour. Ichthyol. vol. 4, pp. 153-61, 5 text figs. [in Japanese, English summary]. Jordan, David Starr, and John Otterbein Snyder 1901. A review of the gobioid fishes of Japan, with descriptions of twenty-one new species. Proc. U. S. Nat. Mus., vol. 24, no. 1244, pp. 33-132, 33 text figs. Newman, William A. 1963. On the introduction of an edible Oriental shrimp (Caridea, Palaemonidae ) to San Francisco Bay. Crustaceana, vol. 5, part 2, pp. 119-32, 3 text figs. Okada, Yaichiro 1961. Studies on the freshwater fishes of Japan. Prefectural Univ. Mie, Tsu, Mie Prefecture, Japan. IX + 860 pp. 2 pls., 133 figs., 61 pls. Temminck, Coenraad Jacob, and Hermann Schlegel 1845. Fauna Japonica, Poissons. 323 pp., 160 pls. [in Siebold, Philipp Franz von, Fauna Japonica, Leyden, 1842-50; the work on fishes is now agreed to have been partly by Schlegel alone, partly by both Temminck and Schlegel]. Martin R. Brittan, Sacramento State College; Arnold B. Albrecht, California Department of Fish and Game, Sacramento; and John B. Hopkirk, University of California, Berkeley; June 1963. printed in CALIFORNIA STATE PRINTING OFFICE 95122 9-63 475 .