GREAT LAKES COREGONIDS 



481 



In all respects these slim terete individuals resemble the shoal herring of Lake 

 Ontario and the upper lakes, and as they are relatively rare and occur but very 

 rarely in the eastern part of the lake, it may be that they are immigrants from the 

 upper waters through the Detroit River, or they may be only rare examples of the 

 extreme development possible to the species. Certainly they spawn along with 

 the typical Erie form, as spawning specimens of both sexes were found in a catch 

 of spawning herring at Sandusky, Ohio, in November, 1920, and unless there is 

 Mendelian segregation, their characters would be unrecognizable in the second 

 generation. 



The other herring at the western end of the lake are but slightly differentiated 

 from those of the east. The most important difference is the greater average size of 

 the catch. The gill nets used throughout the lake are of the same mesh, and while 

 specimens weighing over 1 pound are rare, relatively, in the east, they may at times 

 at least be common in the west. These fish of greater size — jumbo herring — are the 

 eriensis of Jordan and Evermann and are found by Clemens to grow more rapidly than 

 the artedi (of his paper) of the deep water to the east. Except that larger individuals 

 are sometimes somewhat humped at the nape (see p. 478) and that the mandible is 

 less often longer than the upper jaw in the western specimens, 46 there are no constant 

 differences. There are indications that the eastern form may have somewhat more 

 scales in the lateral line and somewhat different proportions, at least as concerns 

 head, eye, maxillary, paired fins, and depth; but the two groups compared were of 

 individuals of different average size, and those proportions that appear to be different 

 are precisely those that are influenced by growth. Experience indicates, furthermore, 

 that the course of a curve like that which might be platted from the data given for 

 lateral-line scales may be altered in either direction to the extent in which the two 

 groups differ from one another by the addition of more data obtained from specimens 

 from another catch. Both jumbos and other herring are found in the same spawning 

 school. 



The eriensis of Jordan and Evermann, which is characterized chiefly by its large 

 size, according to these authors appeared in the catches but a few years before their 

 discovery of it. For many years before Lake Erie had been fished intensively, and no 

 species could have escaped discovery, as these writers seem to imply. On the other 

 hand, the phenomenon of increased size of individuals in a depleted area is not new 

 and has been demonstrated conspicuously in the case of the Lake Erie herring since. 

 The herring were depleted first in the west and were produced more abundantly then 

 toward the east. The jumbos, then, were caught farther to the east, and it is believed 

 by most of the fishermen on the eastern Canadian shore that the fish in these localities 

 have been larger latterly, on the average, than formerly. W. D. Bates, of Ridgetown, 

 Ontario, says that until about 1898 the herring occurred in his pounds in enormous 

 schools and were so small and thin that they were of little value. A fish 1 pound in 

 weight was rare. Now his catch of this species is very light, but individuals frequently 

 weigh 2 to 3 pounds. 



The occurrence of relatively large numbers of individuals with long mandibles 

 in the deep water of the east end of the lake confused Clemens and caused him to 



« In eastern specimens the mandible is shorter than the upper jaw in 241 specimens, equal in 256, and longer in 211; figures for 

 western fish are 42, 35, and 15, respectively. 



