3 2 Memoir Sears Foundation for Marine Research 



occurrence of Sturgeon scutes in materials excavated from prehistoric American Indian 

 villages indicates that these large fish were utilized in aboriginal times {6l: 10-12). 



Hybridization. Hybrids are found in nature quite frequently, not only between 

 different species of Acipenser but between Acipenser and Huso. Antipa described at 

 least eight different types of Sturgeon hybrids (j: 270-273), and recently Antoniu 

 added two new findings among Roumanian Sturgeon (6: 308—313). In some areas, for 

 instance the estuary of the Lena River, Siberia, the hybrid A. baeri x A. ruthenus is 

 much more common than either of the parent species {14: 141). 



Species. At present at least 16 species are recognized, five of which are found in 

 North America. In eastern North America there are three: A. oxyrhynchus Mitchill 

 1 8 14, A. brevirostris LeSueur 18 18, and A.fulvescens Rafinesque 18 17. The two found 

 in the Pacific coastal waters of America are A. medirostris Ayres 1854 and A. trans- 

 montanus Richardson 1836 (p. 36). 



In Europe there are five species oi Acipenser: A. ruthenus Linnaeus 1758, a fresh- 

 water species inhabiting the rivers of the Black Sea and Caspian regions and the Arctic 

 basin from the Ob to the Kolyma; A. nudiventris Lavetsky 1828, of the Black, Caspian, 

 and Aral seas and their tributaries; A. gUldenstcidti Brandt 1833 and A. stellatus Pallas 

 1 77 1, found principally in the Caspian and Black sea regions, but occasionally entering 

 the Mediterranean; and A. sturio Linnaeus 1758, inhabiting both the Atlantic and 

 Mediterranean areas. Furthermore, in his list of Acipenser species, Magnin recognized 

 A. nacarii Bonaparte from the Adriatic Sea as a distinct species {4.8: 280). Chalikov has 

 described a new species from the Caspian Sea under the name of A. primigenius 

 (77: 47-50), but Berg considered it a hybrid A. ruthenus x A. giildenstadti {ll: 77). 



According to Professor Tamezo Mori (personal communication, December 20, 

 1954), seven species of Acipenser are represented in the waters of eastern Asia: 

 A. schrencki Brandt 1869 is limited to the Amur River and Okhotsk Sea; A. kikuchii 

 Jordan and Snyder 1901 and A. multiscutatus Tanaka 1908 are restricted to Japan; 

 A. dabryanus Dumeril 1868 has been reported from only the Yellow Sea basin in 

 China and western Korea; and A. sinensis Gray 1834 is known from China, Korea, 

 and Japan; the sixth, A. medirostris Ayres, which is found on our Pacific coast, also 

 frequents the western Pacific coast; the seventh Asiatic species, A. baeri Brandt 1869, 

 inhabits the Arctic Ocean basin along the coast of Siberia, from the River Ob to 

 Kolyma. Some information on the taxonomic characters and distribution of Asiatic 

 species has been given (5J: 6-10; 54: 1-228; 18: 69-71; $^: 15-17; 72: 65-68). 



Relationship between Species. The total number of gill rakers increases in American 

 species in the following order: medirostris (18-20), oxyrhynchus (17-27), brevirostris 

 (22-29), fulvescens (25-40), and transmontanus (34-36). The American species may 

 be classified in order of increasing development of their bony shields in all the rows 

 (using specimens of corresponding sizes) as follows: brevirostris^ fulvescens, transmon- 

 tanus., oxyrhynchus, and medirostris. Several small plates, with or without a weak crest, 

 are present immediately behind the dorsal fin and in front of the anal; these plates are 

 typically paired in the case of oxyrhynchus but are single in the case of the two other 



