Fishes of the Western North Atlantic 287 



Variations. It has long been generally appreciated that Atlantic Herring in the east 

 do not constitute a homogeneous population, since a number of regional races is in- 

 cluded (pp. 282, 283). Thus "it is possible," writes Norman, "to recognize North Sea, 

 Baltic, Norwegian, Icelandic herring" {lOl). These races differ from each other in such 

 morphologic characters as average proportional dimensions and average numbers of 

 fin rays and vertebrae. But we ought to caution the nontechnical reader that these are 

 numerical averages for many specimens and are not used for the identification of an 

 individual specimen, or of even a few fish; only when the number of specimens examined 

 is large are such figures significant. For example, if the average number of vertebrae 

 was given as 56.3—56.5 for one locality and as 56.6—56.8 for another, it means simply 

 that in the first case there were more fish with 56 vertebrae and less with 57; and in 

 the second case, more fish had 57 and less had 56. No fish ever has a fractional num- 

 ber of vertebrae." 



Each of these races has its own chief center of abundance, its own pattern of sea- 

 sonal migration, and its own spawning season or seasons, for some of the races include 

 both early and late spawners. The races differ in the average size to which their mem- 

 bers grow. A knowledge of the times and localities where these populations are catch- 

 able in greatest amount is of so much commercial importance that these matters are 

 under continuous survey by the fisheries services of the countries chiefly concerned. 



In 1 9 14, Hjort found {6o: 9—12) in the western Atlantic Herring: that the average 

 number of keeled ventral scales is larger (13—14) for the autumn spawners of outer 

 Nova Scotia and the Gulf of Maine than for the spring spawners of the Gulf of St. 

 Lawrence; that the number of vertebrae is greatest (55—59, av. 56.8) in those from the 

 west coast of Newfoundland; that the number of dorsal and anal rays averages higher 

 in those caught in the open sea than in those from the more encloseei waters of the 

 Gulf of St. Lawrence and Bay of Fundy; and that, among the spring spawning popula- 

 tions, the average number of vertebrae, fin rays, and keeled scales is higher in those 

 from the west coast of Newfoundland than in those from the southern part of the 

 Gulf of St. Lawrence. But the fishery for "fat" and for "spawn" fish plays so small a 

 role in the general welfare of Canada and the United States (p. 288) that no additional 

 information seems to have been contributed to the racial question on this side of the 

 Atlantic. From analyses of extensive data, however, Day, Leim, and Tibbo showed that 

 Canadian Atlantic Herring represent six more or less distinct populations, differing 

 from each other in rate of growth and in average number of vertebrae: one in the northern 

 part of the Gulf of St. Lawrence, a second in the Bay of Chaleur, a third in the southern 

 part of the Gulf, a fourth off the outer Nova Scotian coast, a fifth along southern New- 

 foundland, and a sixth along western Newfoundland (see Leim, 8j: 11, figs. 6, 12). 



Commercial Importance. From an economic standpoint, these fish are perhaps the 

 most important in the world. In addition to their great value as food for man, many 



American forms with the northern ones (102:37). Regan's Clupea holodon from New Zealand is now known as 

 Clupea aniipodum (Hector). — G. S. Myers. 

 17. For a general survey of the races of eastern Atlantic Herring, see especially Liibbert and Ehrenbaum (1S9: 14-19); 

 for a detailed study of the average number of vertebrae in the different races, see LeGall {80: 167-170). 



