Habits of the Bluegill 319 



Eagle Lake according to the number of young produced there that year. 

 This would mean that the number of sexually mature fish is about 36,000 

 providing the numbers of males and females were equal. 



At this point arises another question. If there are 18,000 males 

 why have only 2,400 of them constructed nests? There are two possi- 

 bilities. Either more than one male makes and guards a nest or a large 

 percentage of the males are non-functional. The latter solution seems 

 to be the more plausible of the two. All observations point to the fact 

 that a single male guards the nest, when all of the males are driven oflf 

 of a bed of nests the same male is always observed to return to the 

 nest previously occupied. One instance where a single nest was ob- 

 served over an extended period of time jjroved conclusively that the 

 same male remained over a nest until the embryos had left. At first 

 this male seemed extremely shy and at the first alarm he would dart 

 away and remain some distance from the nest. After continued obser- 

 vations he became less alarmed and within a very short time he would 

 remain quiet on the nest with the writer directly above him. If any 

 attempt was made to disturb the male by reaching the hand down into 

 the water he would dart at it furiously with no sign of alarm. 



To determine the population at any one time or to determine the 

 number that reach the adult stage is a very difficult problem due to 

 the many factors involved. The mortality of these young fish is very 

 high, that is from the time of hatching to the self-maintaining stage. 

 The mortality from this stage to maturity is greatly reduced but is 

 still high. 



Enemies. — The worst enemy of the young bluegill is the illegal fisher- 

 man who fishes before the season opens or nets over the nests; or he 

 who marks the beds and fishes the males off the first of the open season. 

 The capture of a very few males leaves thousands of young fry to fall 

 prey to the young bass, turtles and many other carnivorous forms. 



Another serious enemy of the young bluegill is the spawning carp. 

 The carp spawns at a time when the bluegill nesting season is at its 

 height. In the middle of June, 1923, all the nests in one strip along 

 the south shore of the lake were destroyed by the carp as they muddied 

 up the water and uprooted the plants. In this particular instance over 

 40 nests were desti'oyed. 



Summary. — The nest of Lepomis pallidus (Mitch.), the common 

 bluegill, is a saucer-like excavation constructed by the male. Prac- 

 tically all of the nests are found inside of the two-meter contour line, 

 which is the shelf of the lake where the water rapidly becomes deeper. 

 These nests are never found in dense growths of aquatic plants and are 

 always found in clusters. 



The accompanying illustrations (figs. 1, 2, and 3) of Eagle Lake, 

 which has an area of a little less than a square mile (556 acres), indi- 

 cate the location and number of nests found in the years, 1921, 1922, 

 and 1923, respectively. From four typical nests all the embryos were 

 collected and counted, the average per nest was 86,631. From these 

 counts it is estimated that approximately 207,000,000 bluegills were 

 hatched out in Eagle Lake in 1923. 



