PROGRESS IN BIOLOGICAL INQUIRIES, 1926 661 
very elongate and terete in form, with a body depth of one-fifth its length, and 
the other with a short, much compressed body, with a body depth of one-third 
the length. Both forms may spawn together. About 10 specific names have 
been given to this single species in the Great Lakes. 
In Lake Superior two species resemble each other so closely that they can be 
distinguished only by the value of the fraction, which for numerator has the 
sum of head depth and base of the anal fin and for denominator the sum of 
the maxillary and snout; and even these values, for the two species, are not 
exclusive. The fish are, nevertheless, very distinct in their habits. One spawns 
in September in deep water; the other in November along the shores. So much 
for structures. 
Byven the habits of the various races of a species may not be alike in different 
areas. One species in Lake Michigan spawns in May, while in Lake Ontario its 
representatives, which can not be distinguished from their brethren in Lake 
Michigan, spawn in January. Even in a restricted locality, one school of the 
true whitefish may spawn on one reef in October while another reef, a few 
miles away, may not be visited by spawning fish until December. 
Where such variability exists, members of a species may differ more from 
one another than from individuals of other species; two species may be almost 
exactly alike in their structural features and the breeding habits of races of 
the same species are entirely different. 
I would not have you believe, however, that the situation remains so obscure 
and confused that no one but me will ever be able to identify the Great Lakes 
whitefishes. I have been able to send descriptions of desired species to 
various fishermen and have received in return collections of the fish I wanted. 
It must be apparent, also, that it is possible to describe the fishes in simple 
terms, for no fisherman would attempt to interpret the descriptive formulas 
that systematic ichthyologists have found necessary to employ in portraying a 
species. 
The coregonids, like most of the other Great Lakes fish, are taken by the 
fishermen with gill nets and traps. Most of them have been the object of 
commercial fisheries for more than 50 years. Until their numbers were so 
seriously depleted that it became apparent that some protection must be 
granted, fishing was unrestricted. The fishermen were allowed to catch fish 
of any size, in any quantity, at any time. Even after protective laws were 
put on the statute books, usually they were not enforced immediately. In 
late years some kind of minimum-mesh laws have been enacted and usually 
enforced, and in some places one species—the whitefish—has been more or less 
protected in the spawning season. These fish thus have sustained an almost 
unrestricted fishery, whose effects have been tempered only by the “law” of 
supply and demand. Fortunately, the supply has, until recently, exceeded the 
demand. In 1925, however, the impossible, the incredible, happened. The 
herring of Lake Erie, suddenly and without warning, gave out. Where in 
1924 the fish could be caught by the ton, in 1925 only stray individuals could 
be found, though dozens of boats, with miles of nets, set virtually from top to 
bottom in the lake, undertook the search. In 1926 the fish still failed to appear. 
A fishery that annually yielded as many high-class fish as could be sold (around 
25,000,000 pounds, about one-sixth of the Great Lakes total yield) was no 
more. 
It has been mentioned before at these meetings that though the Great Lakes 
yield has been maintained at about a constant figure, it has been achieved only 
by the capture of undesirable species to repiace the choice ones that have be- 
come rare. The Great Lakes have now no more unexploited species, except the 
shiners that throng the shores, and the loss of one-sixth of the production 
of the choicest fish marks the last chapter in the history of a once important 
industry. The herrings everywhere in other lakes have been sought to fill 
this gap in production. These species probably never have been collectively 
numerous enough to supply so great a quantity of produce, and in their 
seriously depleted condition the intensive fishery to which they are conse- 
quently subjected must unavoidably exterminate them also. One species is 
already extinct in all but one of the lakes. It follows, further, that the de- 
mand for species of fish other than coregonides will increase as they decline, 
and the fishery for these species must then hecome still more intensive, with 
possibly catastrophic consequences, 
The most significant lesson that depletion has taught in the Great Lakes is 
that species once reduced never recover. Furthermore, it is not clear how the 
