704 BULI<ETIN OF THE BUREAU OF FISHERIES. 



WHITE PERCH. 



With the decadence of the valuable shad fishery there has arisen a demand 

 for the artificial propagation of the white perch (Morone americana), and this 

 work has been extensively conducted at the mouth of the Susquehanna River 

 during the past four seasons in connection with the hatching of shad. Like 

 shad culture, the propagation of white perch is purely the conservation of eggs 

 which would otherwise go to market in the parent fish. 



The spawning season in the latitude of the Bureau's station at Havre de 

 Grace, Md., is from the middle of April to the latter part of May, the time varying 

 with the character of season. The eggs are taken and fertilized by the usual 

 dry method, the work being performed ordinarily by the fishermen. Owing to 

 the adhesiveness of the eggs it is preferable to strip them into marbleized or 

 porcelain-lined pans. 



As with shad and other spring spawning fishes, the white perch spawns on 

 a rising temperature, ripe fish being taken first when the temperature is about 

 47°. However, the eggs seem to produce better results when hatched in water 

 of a higher temperature. At about 60° F. they hatch in forty-eight to fifty- 

 two hours, while at 68° to 70° they hatch in twenty to twenty-four hours. 

 They are sensitive to sudden diops in temperature, and although at 58° or 60° 

 about 75 per cent of the eggs produce vigorous fry, at 50° or lower few if any 

 eggs or fry survive. In one case eggs taken at 56° and held for twenty-four 

 hours, after which the temperature dropped to 46°, finally hatched at a temper- 

 ature of 54°. producing a fair percentage of fry. Observations thus far made 

 indicate that eggs taken at mid-day or soon after mid-day produce better 

 results than those taken earlier in the morning, although the reason has not 

 been ascertained. 



After being held for from six to twelve hours in jars without tops, white 

 perch eggs are incubated and hatched in McDonald automatic jars on shad 

 tables in the same manner as shad eggs. As they are especially liable to fungus, 

 a good circulation is particularly important, and it is inadvisable to carry more 

 than one-fourth capacity to a jar, or from 800,000 to 1,000,000. The eggs are 

 comparatively heavy, and for this additional reason require more water circu- 

 lation than is needed for shad, or 2}4 to 3 quarts per minute. It is customary 

 to reduce the flow about one-half during the last few hours before hatching, in 

 order that fungussed masses and attached good eggs ma)' not be carried out 

 into the receiving tank. 



Wlien undeveloped the eggs are very white and hard, and it is difficult for 

 the novice to tell the live ones from the dead. Some that apparently are dead 

 suddenly eye and hatch, while, on the other hand, some apparently of good 

 quality frequently fungus and prove a total failure. By examining in a glass 



