294 
BULLETIN OF THE BUREAU OF FISHERIES 
Development of species — Continued. Page 
Family Percidae, perches — Contd. 
42. Percina caprodes zebra 371 
43. Rheocrypta copelandi 373 
44. Boleosoma nigrum nigrum.. 374 
45. Poecilichthys coeruleus coe- 
ruleus 376 
46. Poecilichthys exilis 377 
47. Catonotus flabellaris 377 
Family Centrarchidae, sunfishes 378 
48. Micropterus dolomieu 378 
49. Aplites salmoides 380 
50. Eupomotis gibbosus 381 
51. Ambloplites rupestris 382 
Family Atherinidse, silversides 383 
52. Labidesthes sicculus 383 
Development of species — Continued. Page 
Family Sciaenidae, drumfishes 383 
53. Aplodinotus grunniens 383 
Family Cottidse, sculpins 385 
54. Triglopsis thompsoni 385 
55. Cottus bairdii kumlieni 387 
56. Cottus bairdii bairdii 389 
57. Cottus cognatus 390 
58. Cottus ricei 391 
Family Gasterosteidae, sticklebacks.. 392 
59. Eucalia inconstans 392 
60. Gasterosteus aculeatus 392 
Family Gadidae, codfishes 393 
61. Lota maculosa 393 
62. Species A 396 
Bibliography 397 
INTRODUCTION 
That tremendous mortality among fishes must occur is evident from the fact 
that the individuals of many species spawn thousands and often millions of eggs yearly 
without an appreciable increase in the numbers of adult fish. Undoubtedly a high 
percentage of destruction is normal and necessary in suppressing overproduction and 
providing food for other organisms. Sometimes, however, this mortality becomes 
abnormally large, due either to unfavorable environmental conditions or the inroads 
of man, and the stock is seriously depleted. It is generally believed that the greatest 
losses at such periods take place during the egg stage or soon after the free-swimming 
larva emerges; hence the need for studying early life histories is apparent. 
Although much has been done on marine fishes, practically nothing beyond frag- 
mentary notes for a few species has been available on the developmental stages of their 
fresh-water relatives. No one has previously considered this embryonic, larval, and 
postlarval community as a whole. The study of early life histories, dovetailed with 
an investigation of biological, physical, and chemical conditions of the environment, is 
necessary in order to understand problems of production, abundance, and depletion in 
fish fauna, to determine the causes of yearly class fluctuations and their ultimate 
effect upon commercial fishing, or to solve other problems of real economic importance. 
Such a comprehensive survey has been attempted in Lake Erie, and the present paper 
is one of a series which will result from that study . 2 
The first step in the fish problem had necessarily to be the identification of the 
young of each species in various developmental stages. Thus, the following text 
deals, for the most part, with descriptions of specimens taken in net hauls. Because 
of this manner of collection the fife history series are seldom as complete as desired, 
but all young fish taken by the cooperative survey of Lake Erie in 1928 and 1929 are 
included in the distribution tables, and whatever developmental stages were found 
are described and figured under the various species heads. 
Statistics compiled recently by the United States Bureau of Fisheries show the 
annual value of the Great Lakes fisheries to total nearly nine millions of dollars. In 
Lake Erie alone in 1927 the catch brought $1,831,284 to American fishermen. Such 
an industry can not be disregarded, and when it declines noticeably, the need of 
8 Preliminary reports have appeared in Vol. XIV, No. 3, and Vol. XV, No. 1, Bulletin of the Buffalo Society of Natural Sciences, 
and in “A Biological Survey of the Erie-Niagara System,” Supplemental to the Eighteenth Annual Report, 1928, New York State 
Conservation Department. Further reports will be published in forthcoming Bulletins of the U. S. Bureau of Fisheries. 
