798 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



From the eggs hatched at the station during the season we have now 

 in our ponds for distribution during the fall of 1887, according to the 

 estimates of the superintendent of the station, about 00,000 California 

 and Eastern brook trout, from 3 to 5 inches in length. 



During the spring of 1887 our facilities for pond-culture were extended 

 by the construction of a series of ponds covering about 2 acres, for the 

 cultivation of the rock bass (Ambloplitcs rupestris), a species well adapted 

 for pond-culture and rapidly growing in favor with those desiring a 

 species of easy cultivation, with gamy characteristics and of good flavor. 



The landlocked salmon bred during the season were held in ponds at 

 the station until June, 1887, and then transferred to the headwaters of 

 the Shenandoah Eiver, in Augusta County, Va. They were from 2£ to 

 3 inches in length when planted, and about 25 per cent, only of the 

 eggs received survived. 



The stocking of the headwaters of the Shenandoah with salmon is to 

 be regarded as an experiment in acclimation rather than assured fish- 

 cultural work. It is hoped that by the selection of a variety of salmon 

 that has largely lost its migratory instincts and by hatching it and 

 constraining it to live for some months in a much higher range of tem- 

 perature than is natural to it, it may become habituated to its new en- 

 vironment and become resident in the Potomac River basin. Should 

 but a few survive and spawn it is probable that the young will exhibit 

 considerable modification of habit and be in better accord with their 

 environment, and after a succession of generations develop a distinct 

 race, finding congenial habitat in streams with a higher range of tem- 

 perature than is found in the natural salmon streams of the Northeast. 



It is not possible to report even a fair measure of success in hatching 

 eggs of the Brown Trout of Europe {Salmo fario). From the Deutsche 

 Fischerei-Yerein we obtained about 2,000 fish, which, at the age o six 

 months, are from 4 to G inches long and growing rapidly. The very 

 large percentage of loss occurred during the period intervening between 

 hatching and beginning to feed. 



(5) rrovision for pond culture. — In the oval depression north of the 

 hatchery (Plate 1) are two ponds, 12 by 50 feet, provided with spawning 

 races. These are reserved for our breeding trout. They are constructed 

 entirely of plank, sides and bottom, and at first the sides projected 

 above the level of the soil. The considerable losses occurring among 

 the breeders during the hot weather of summer indicated unhealthy 

 conditions, which were attributed to the exposed sides, which became 

 heated during the day, thus causing a considerable rise in the tempera- 

 ture of the water. This was remedied by banking up the sides with 

 earth and sodding the slopes. The plank bottoms at the upper ends of 

 the ponds were also covered by broken stone and coarse gravel. These 

 changes were marked by the greater improvement in the condition of 

 the fish in the ponds. Losses are now comparatively rare, .and are al- 

 most entirely confined to the males, being usually the result of injuries 



