12 



U. S. BUREAU OF FISHERIES. 



plant ingestion some 2*0 times less frequent, it appears reasonable 

 to believe that the oranfje-spotted sunfish, which is small and pro- 

 lific, is a very considerable agent for mosquito control wherever and 

 whenever mosquito-egg deposition oecui-s in its environment; and 

 this is, by our observation, a common occurrence. The sunfish may 

 not be as effective as Gambusia, however, even though its diet would 

 appear more favorable, since the latter's very small size and surface- 

 feeding habit make it a serious enemy of the surface-living mosquito 

 larvae. 



, VALUE OF THE ORANGE-SPOTTED SUNFISH. 



Lepomis humilis, because of its small size, even when fully grown, 

 has little or no value as a sport or food fish, though when it reaches 

 a 3 or 4 inch length it takes the hook readily. Its value in the field 

 of food and sport lies indirectly in its utilization as food by those 

 carnivorous fishes that are especially valued by the angler and epi- 

 cure. That the fish has a genuine significance in this connection has 

 been proven in the culture of the large-mouth black bass in the ex- 

 perimental ponds at Fairport, Iowa. 



Accurate data regarding the usefulness of kimiHis as a forage fish 

 have been obtained. In 1917 in the Fairport Pond D 3, area 0.846 

 acre, tliere were liberated in early spring 51 adult black bass and 

 1,238 adult and 990 young Lepomis humilis of one growth year. In 

 (Jctober of the same year there were obtained from the pond 9,234 

 3 to 5 inch bass fingerlings (rate of 10,915 per acre) and only 

 626 adult hwniilis. Johnson and Stapleton (1921), experienced prac- 

 tical fish-culturists, have made the statement that " a 2-acre pond pro- 

 ducing 10,000 1-year-old black bass from 4 to 6 inches long would be 

 a remarkably successful enterprise." The fact that no orange-spotted, 

 sunfish of the current year's production survived the season (Table 

 5) indicates that the bass were making use of them as food. The 

 parental protection given the bass eggs prevented any depredations 

 by the simfish as eggeaters, and the later rapid growth of the bass 

 fry carried them quickly out of the realm of possible attack and 

 made them at an early age the enemies of the sunfish. 



Table 5. — The oranije-i^potted sunfish in larf/e-mouth bUick-hass mlture. 



Seventeen of these removed during the summer. 



Not alone does the sunfish possess value because it serves as fish 

 food. The important factor of its utility lies rather in that it is the 

 prime agent in the economy of a bass pond, for the sunfish trans- 

 forms into its flesh many of the minute water fleas and insects that 



