122 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



deut to transler being' small. About 20 per cent of eggs obtained here 

 were uninipregnated, but tlie relative loss in tlie season's hatcliing was 

 small. Could the rack have been placed earlier on the Sandy Kiver it 

 is believed that larger collections could have been made, the migration 

 of fish having been in i)rogress two mouths before comiileting the rack. 



The liberation of fry was commenced December 29, continuing almost 

 daily, as they devel()])ed, until April 20, deposits being made in the 

 Clackamas Kiver and in Clear Creek, a tributary. The young were 

 scattered over an area of about 5 miles. lu January the water tem- 

 I)erature was very low, and as a result of ice formation in the troughs 

 the flow was almost cut oft'. In the cold water the devel(>i)nK'nt of fry 

 was retarded, and but few were released during the mouth. Those 

 released in February amounted to about 1,000,000, in March to 1,500,000, 

 and in April to about 1,000,000, the total reaching 4,100,000. 



After the termination of the egg-collecting season the racks and 

 inclosures on the Clackamas were removed and stored above the freshet 

 line. From the commencement the pumj) was required to supply the 

 hatchery, it being employed throughout November with the exception 

 of three days. It was also used occasionally in December, but after 

 December 21 there was, as a result of rainfall, sufficient brook water. 

 On February 1 and 2 snow falling in the brook compelled constant 

 attention to keep the water flowing. Once during February and again 

 early in April Clear Creek was very high, floating one end of the bridge. 



On February 7 there were received from Northville Station 20,000 

 eggs of brook trout. These arrived in good condition and hatched with 

 slight loss, but the young began dying just before the sac was absorbed, 

 all soon perishing. After March 31 the station force was reduced. 



Aquaria, Central Station, Washington, D. C. (L. G. Harron, in charge). 



Both fresh-water and marine species were successfully maintained for 

 purposes of study. Before the expiration of the fiscal year the super- 

 intendent was temporarily transferred to Chicago, where he was in 

 immediate charge of the salt-water section of the aquaria maintained 

 by the United States Fish Commission. The salt-water section at 

 Chicago having proved relatively more successful than the fresh-water 

 section, it is apparent that studies carried on at the aquaria in Wash- 

 ingtcm brought about the result, the water in Chicago being circulated 

 and aerated after the processes developed heie. 



In July, 1892, an exi)eriment was made looking to the reduction of 

 temperature in the a(piaria by applying ice to the pipes in which salt 

 water was circulated, but the consumption ran up to about 2,000 pounds 

 j)er day, making the cost too great. No attempt has been made to 

 reduce tenq)erature by application of compressed air. The salt water 

 being in (circulation and subject to surrounding air temperature, reaches 

 a high point in the warm months, attaining 88° in August. In winter 

 it is also subject to low temperatures, which, however, are not so 

 extreme, the surrounding air being tempered by means of artificial 



