DEVELOPMENT, GROWTH, AND FOOD HABITS OF THE 
WHITE SUCKER, CATOSTOMUS COMMERSONII LESUEUR 
& 
By NORMAN HAMILTON STEWART 
• 5 * 
CONTENTS 
Page 
Introduction 147 
Description and distribution of Catosto- 
mus 148 
Breeding habits 149 
Development of the egg 152 
Condition at laying 152 
Number of eggs laid 152 
Spermatozoa 152 
Fertilization 153 
Water hardening 153 
Cleavage 153 
Period of incubation . 154 
Cleavage stages 154 
Newly hatched larva 157 
Development of the larva 158 
Digestive tract 158 
Pigmentation ; 158 
Fins 158 
Peculiar change in location of mouth_ 159 
Histology of the mouth. Oral epi- 
thelium 161 
Page 
Development of the larva — Continued. 
Histology of the intestine 163 
Adult condition 165 
Coiling .. ... 167 
Determination of age 168 
Relation between growth of scales 
and size of fish 168 
Seasonal irregularities in the circulL. 170 
Annual growth 172 
Food and the feeding habits of the white 
sucker — 173 
Review of the literature 173 
Food 174 
Periods into which feeding habits 
may be divided 175 
Detailed account of feeding habits 
and food . 176 
Summary 181 
Economic status of the sucker 183 
Bibliographjr ' 183 
INTRODUCTION 
It is the aim of the present paper to present an account of the development 
and biological relationships of the white sucker. Not many papers dealing with 
single species of our fresh-water fishes have appeared up to the present, but the 
complex problems of the interrelationships of aquatic organisms will be simplified 
only by more complete knowledge of the lives of individual species. The role played 
by any species of fish in the economy of stream life varies with its age and feeding 
habits; hence it is profitable to consider the part played by such a species at every 
stage of its life. This is attempted in the present paper by bringing together obser- 
vations extending over a year, and thus including an account of the activities of 
the sucker during each year of its life and at each season of the year. 
As this species is remarkable for its adaptability as well as for its general abun- 
dance, it becomes one of the factors that may alter the environment in which the 
