FAMILY PERCIDAE 213 



26,000 eggs per pound of fish. The individual variation is high, the num- 

 ber in 3- to 3 1/2-pound females varying from 72,000 to 110,000. 



The proportion of males to females varies little from season to season. 

 At the Bemidji station it was found that during the course of a season's 

 run, which usually covers a period of two to three weeks, depending on 

 weather conditions, the proportion of males to females was on the aver- 

 age two males to one female. This finding agrees with the records kept 

 at other stations. 



Even in nature the production of walleyes is not economical. An 

 enormous quantity of natural food is required to produce a pound of 

 this strictly carnivorous fish. Forbes and Richardson (1908) estimated 

 that, reckoning the average hfe of a walleye at three years, the smallest 

 reasonable estimate of food for each one would fall somewhere between 

 1800 and 3000 fishes, and this estimate is probably conservative. Adult 

 walleyes kept in the aquaria at the University of Minnesota will eat 

 from 10 to 20 small fish a day. During the winter the walleye, like the 

 perch, remains active and continues to feed. Consequently it is readily 

 caught through the ice during the winter months. It bites less readily 

 during the last half of February and usually ceases to bite in March as 

 the spawning season approaches. 



Subfamily ETHEOSTOMINAE 

 the darters 



The darters comprise a variety of forms difficult to identify unless 

 thoroughly studied. All darters are American fishes, and they are 

 found only east of the Rockies. They differ distinctly from other mem- 

 bers of the family Percidae and have therefore sometimes been placed 

 in a separate family called Etheostomidae. They are differentiated 

 from the other Percidae by their small size, unforked or weakly forked 

 caudal fin, usually 6 branchiostegal rays, and shghtly developed 

 pseudobranchiae (false gills on the under side of the opercle) , and by 

 the character of the serrations on the opercles, which are very slight if 

 present at all. They are all small, perchlike fishes of slender form with 

 fins, particularly the pectorals, highly developed. The colors of the 

 males during the spawning season are the most brilhant found in any 

 of our fresh-water fishes. This brilliant coloring and the unusual habits 

 of the darters make them by far the most interesting small fishes we 

 have. 



Many years ago Jordan (1888) wrote of the darters: "Any one who 

 has ever been a boy and can remember back to the days of tag-alders, 

 yellow cowslips, and an angleworm on a pin-hook, will recall an experi- 

 ence hke this: You tried some time to put your finger on a little fish that 

 was lying, apparently asleep, on the bottom of the stream, half hidden 



