PROGRESS IN BIOLOGICAL INQUIRIES, 1921. 



19 



aquatic vegetation the blue-spotted sunfish will prove a valuable 

 addition, and if very shallow or swampy areas occur, the mud min- 

 now. The common killifish is very effective in fresh and brackish 

 tidal marshes, and the translucent killifish is useful in upland creeks 

 and dams. Rapid multiplication of small fishes should be encouraged 

 by providing suitable nesting sites and protection for the fry. 



Gambusia, the favored top minnow of southern waters, has not 

 survived the northern winters but multiplies so rapidly that it may 

 be used effectively against both Culex and Anopheles in small ponds 

 and water gardens by planting a small number each spring. Small 

 goldfishes are useful in fountain basins and small i)onds with clean 

 sides, and, for use in rain barrels and tanks, are preferable to Gam- 

 busia. 



FISH-CULTURAL EXPERIMENT WORK. 

 EXPERIMENTS IN PROPAGATINrx AND REARING EISH IN PONDS. 



The Fairport station has continued its valuable experimental work 

 in reference to the propagation and rearing of fishes in ponds. Cer- 

 tain observations were made on the value of fertilizing ponds with 

 chemicals and manure, but data obtained to date are inconclusive. 

 Further study will be directed toward this problem. 



The small pond, which for several years has been handled as a farm 

 pond with minimum care and expense, has yielded valuable informa- 

 tion. Originally it was stocked with bluegill sunfish. Occasionally, 

 when necessary, the pond has been wintered out. There has been no 

 manipulation of the pond in any respect other than the control of the 

 number of bluegills of various ages in it. During the past year the 

 actual production of fish meat in the ponds has been 333 pounds per 

 acre. Of this, however, fishes of edible size represented about 33 per 

 cent of the total fish-meat production. In this connection it may be 

 well to note that the average annual production of beef per acre on 

 untilled meadowland is said to be 125 pounds; that for hogs is 225 

 pounds. 



Buffalofish, Ictiohus c]ifrineTla^ artificially reared in the station 

 ponds, reached maturity and produced young for the first time at the 

 age of 4 years. They averaged 13.6 inches in length and approxi- 

 mately 2 pounds in weight. The small-mouth buffalofish, Ictiohus 

 hubalus^ which in previous years had failed to spawn in the experi- 

 mental ponds unless an artificial rise in the level of the pond was 

 produced, spawned this year in a pond in which the rise did not 

 occur. While the production of fry of this species does not appear 

 to be as numerous as for those fish held in the pond with artificial 

 rise, the occurrence indicates that the rise is not entirely necessary, 

 though it may be advantageous. 



The channel catfish, Ictaluriis functatus^ for w^hich this station 

 showed the feasibility of pond culture, has continued to spawn in the 

 experimental ponds. Certain 4-year-old offspring of wild stock came 

 to sexual maturity during the year and produced the first brood of 

 truly domestic fish. The adaptability of this species to pond culture 

 is suggested by the fact that the catfish has spawned in certain of the 

 smallest ponds on the reservation, one of which has a water-surface 

 area, Avhen completely full, of only 3,485 square feet (less than one- 

 twelfth of an acre). 



