30 U. S. BUREAU OF FISHERIES. 



pendent on the lake-trout fishei-y and the urgent need for exercising 

 the most careful conservation in order to maintain the supply, the 

 bureau has for a number of years found it expedient to distribute 

 the output of its lake-trout hatcheries on the local spawning 

 grounds from which the eggs are obtained. The fry are placed in 

 the ordinary 10-gallon cans used in the distribution work, one tray 

 of fry being carried to each can for medium distances. They are 

 frequently transported in the bureau's distribution cars to a con- 

 venient lake port and thence by means of a fishing steamer to the 

 planting areas. However, most of the plants are made by placing 

 the cans of fish on regular commercial vessels employed for the 

 trip. At the Charlevoix (Mich.) station, where the bureau has a 

 boat equipped with two troughs, the trays of fish are carried from 

 the hatchery to the boat, a distance of 100 feet, and placed in troughs, 

 which are supplied with running water by a pump. Since the con- 

 ditions are the same as in the hatchery, the fry may be carried long 

 distances without loss. Allotments of lake-trout eggs are not in- 

 frequently supplied to various State fish commissions, where this 

 course will result in economy in distributing the resulting fry or 

 where possibilities exist for extending the fishery to new and unpro- 

 ductive fields. 



PACKING EYED EGGS FOR SHIPMENT. 



Just as soon as the eye spots are plainly visible the eggs can 

 be packed and successfully shipped to any part of the United States 

 or to most of the foreign countries, provided they are maintained 

 at a uniform temperature. The shipping trays are usually con- 

 structed of material three-fourths inch thick by 1 inch wide, and 

 the bottoms are covered with linen scrim or heavy cheesecloth. The 

 size of the trays depends upon the number of eggs to be shipped. 

 For a 50,000 case of eggs 12 trays 14 inches square are used. After 

 installing the eggs on them the trays are placed one above another 

 in the egg case. The ice hopper is then inserted and the pressure 

 of the lid holds down the entire lot. For shipments to points within 

 the United States where the eggs will not be en route more than four 

 or five days the packing case is insulated with a 1^ or 2 inch thick- 

 ness of ground cork. 



In preparing the shipment the temperature of the room in which 

 the eggs are to be packed should not be higher than 40° or lower 

 than 26° F. The trays are first stacked in order on a table to re- 

 ceive the eggs; then a compartment of eggs that has been pre- 

 viously picked and cleaned is taken from the trough and carried 

 to the packing room in a tub of water. The day before the ship- 

 ment is to be made up the eggs are usually poured from one pan to 

 another, the slight concussion resulting being sufficient to cause all 

 infertile eggs to turn white. In the packing room most of the water 

 is poured from the tub, and the eggs are removed by the use of a 

 graduated dipper with perforated bottom and placed in a 16-ounce 

 glass graduate. The proper number of ounces is then poured onto 

 each tray, the trays having previously been spread with mosquito 

 bar from 4 to 6 inches wider than their outside dimensions. The 

 eggs are carefully distributed over the surface of the tray, as already 

 described, and the edges of the mosquito bar brought in and lapped 



