Abstract. — Two species of sand 

 lances are recognized in the western 

 North Atlantic, the inshore Ammo- 

 dytes americanus DeKay 1842 and 

 the offshore A. duhiua Reinhardt 

 1838. The best separation of the two 

 species is achieved by using the num- 

 ber of plicae (oblique folds of skin on 

 the lateral body surface) singly or in 

 combination with the number of ver- 

 tebrae. Ammodyte^ ameyicanus has 

 fewer meristic structures than A. 

 dubius: number of lateral plicae 106- 

 126, X 117.4 vs. 124-147, 132.1; 

 total vertebrae 62-70, x 66.4 vs. 

 68-76, 70.8; dorsal fin rays 52-61, 

 X 57.4 vs. 56-67, 61.8; anal fin rays 

 26-33, J 29.4 vs. 28-35, 31.1; pec- 

 toral fin rays 11-15, x 13.2 vs. 12- 

 16, 14.0; gill rakers on first arch 21- 

 28, X 24.3 vs. 23-31, 26.6. Meristic 

 differences between species were 

 summarized with principle compo- 

 nent analysis. In addition to con- 

 siderable variation within samples, 

 there is geographic variation in num- 

 bers of vertebrae, plicae, and dorsal 

 and anal fin rays, particularly in the 

 offshore A. dubius. Specimens from 

 the Scotian Shelf north have higher 

 counts than do specimens from more 

 southern populations. Based on spec- 

 imens e.xamined, A. americanus oc- 

 curs from southern Delaware north 

 to Labrador in shallow coastal waters 

 as well as in protected bays and es- 

 tuaries. Ammodytes dubius is found 

 in deeper, open waters from North 

 Carolina to Greenland. 



Separation of Two Species of Sand 

 Lances, Ammodytes americanus 

 and A. dubius, in thie Western 

 iMortli Atiantic 



Martha S. Nizinski 

 Bruce B. Collette 

 Betsy B. Washington 



National Systematics Laboratory, National Marine Fisheries Service. NOAA 

 National Museum of Natural History, Washington, DC 20560 



Manuscript accepted 26 January 1990. 

 Fishery Bulletin. U.S. 88:24 1-255. 



Members of the genus Ammodytes, 

 or sand lances, are small elongate 

 fishes abundant over shallow, sandy 

 areas of the continental shelves of 

 northern oceans. They are important 

 prey items for several commercial 

 fishes (e.g., American plaice, cod, 

 haddock, silver hake, yellowtail 

 flounder, and Atlantic salmon (Reay 

 1970, Meyer et al. 1979, Winters 

 1983) as well as fin and humpback 

 whales (Overholtz and Nicolas 1979) 

 and various kinds of seabirds (Reay 

 1970, Powers and Backus 1987). 

 Additionally, in the North Sea and 

 off Japan, sand lances are the basis 

 for an important fish-meal industry 

 (Macer 1966). 



Western North Atlantic popula- 

 tions of sand lances have increased 

 dramatically in recent years (Sher- 

 man et al. 1981, Winters 1983). This 

 population explosion was correlated 

 with a decline in stocks of herring 

 Clupea harengus and mackerel Scom- 

 ber scombrus along the eastern coast 

 of the United States (Population 

 Dynamics Branch, Conservation and 

 Utilization Div., Northeast Fish. 

 Cent., Natl. Mar. Fish. Ser\'., NOAA, 

 Woods Hole, MA 02543) (Fig. 1). The 

 opportunistic sand lances seemed to 

 have replaced these stocks. Concur- 

 rently, piscivorous fishes increased 

 their consumption of sand lances. 

 Peak abundance of sand lances in this 

 region was readied in 1981, and 

 numbers have since decreased 



(Nelson and Ross 1987). Again, the 

 shift in sand lance abundance was 

 correlated with mackerel numbers; 

 mackerel populations have been 

 steadily increasing since 1983 (Fig. 

 1). In view of the ecological impor- 

 tance and population dynamics of 

 sand lances, it is important that the 

 taxonomic status of these fishes be 

 resolved. 



Although the taxonomy of the 

 majority of fish species in the west- 

 ern North Atlantic Ocean is known 

 reasonably well, Ammodytes is a 

 major exception despite the results 

 of several detailed studies (e.g., 

 Richards et al. 1963, Scott 1972, 

 Winters and Dalley 1988). Recogni- 

 tion of two species of Ammodytes in 

 the western North Atlantic dates 

 back to at least Jordan and Ever- 

 mann (1896). Since then, the major- 

 ity of researchers have fundamental- 

 ly accepted this finding (Bruun 1941, 

 Backus 1957, Richards et al. 1963, 

 Leim and Scott 1966, Winters 1970, 

 Scott 1972, Winters and Dalley 1988, 

 Scott and Scott 1988). However, final 

 conchisions on species names, syn- 

 onomies, and meristic and geograph- 

 ic ranges vary between studies. 

 Ammodytes americanus DeKay 1842 

 and .4. dubius Reinhardt 1838 are 

 currently accepted as the appropriate 

 names for these sand lances (Leim 

 and Scott 1966, Reay 1970, Richards 

 1982, Winters and Dalley 1988), and 

 until a worldwide systematic revision 



241 



