FISH. 243 



FISH. 



BY ADELBERT L. LEATHERS. 

 GENERAL DISCUSSION. 



The fish inhabiting the waters in and about the sand region of Huron 

 County, Michigan, were studied as carefully as the season, the limited 

 time, and the means at hand would permit. The object of this study 

 was not so much the investigation of particular problems as to increase 

 our knowledge of the distribution of the species in the state. 



The aquatic habitats of the sand region present a number of pecu- 

 liarities which have a profound influence upon the number and dis- 

 tribution of the fish. The lakes and ponds have neither outlets nor 

 inlets, and the water they contain and their permanence is thus largely 

 governed by the amount of rainfall in their immediate \ncinity. The 

 sandy .soil permits the excess of water to escape without overflowing, 

 except where the banks are low and then only when the rainfall is ex- 

 cessive. The bottoms of the lakes and ponds were originally sandv 

 but they are now covered by an ooze resulting from the disintegration 

 -of aquatic vegetation. 



Long Lake, Orr Lake and Rush Lake are examples of the larger 

 bodies of quiet water. Long Lake (PI. Xlla) appears to be without 

 a fish fauna. Grass Lake apparently contains only the mud minnow, 

 which, however, seems to thrive there. Rush Lake (PI. IX). the largest 

 and deepest of the lagoon lakes of Huron County, although outside of 

 the sand region proper, presents similar conditions. It has no outlet 

 through which fish would be liable to enter or escape, and the only in- 

 let is a county drain connecting it with a marshy region located within 

 its hydrographic basin. This lake has extensive shallow areas where 

 the bottom is composed of ooze that overlies the sandy substratum to a 

 depth of from two to five feet. During the driest part of the season 

 about a third of this area is exposed, although the fafl of the lake is not 

 more than six inches below the average level. Towards the north shore, 

 however, there are areas of open water which have a depth of six or 

 seven feet. The fish fauna is quite abundant and varied, but minnows, 

 catfish'and pike are apparently the most numerous forms. 



The streams in the sand region all communicate with Saginaw Bay, 

 and consequently their fish faunas do not suffer permanently from ad- 

 verse conditions. The habitats consist of two types — the flowing 



