PACIFIC SALMON FISHERIES. 205 



A more modern method in use atmany hatcheries, which has been 

 well described by Mr. Bower," is as follows: 



The Iong-fono"wed process of taking Pacific salmon eggs by hand expression has been 

 superseded in the last fe'w years by the method of incision, a method discovered and 

 de'veloped by the late Cloudsley Rutter in connection with his study of the life history 

 of the salmon of the Sacramento River. This consists simply of making a cut in the 

 abdominal walls from the throat or near the pectoral fins to the vent, the fish just 

 pre\iously having been killed by a blow on the back of the head. When making the 

 cut the knife is either shielded by a guard or is so held between the thumb and fore- 

 finger as to allow not more than half an inch of the blade to project, thus precluding the 

 possibility of injuring any of the eggs. Immediately following the incision the eggs 

 flow in a mass into the spawning pan beneath. The operator's fingers are inserted 

 into the abdominal cavity gently to assist in removing any eggs that may be enfolded 

 in the organs or that may merely adhere to the walls of the cavity. P^ertilization is 

 accomplished in the usual manner. 



Care must be exercised not to tear loose from the ovaries any eggs that do not come 

 freely when the organs are moved from side to side by the fingers. Eggs thus torn 

 loose are immature, and if taken it becomes necessary to eliminate them subsequently 

 in the hatfhery. It is preferable also to have the fish either in a Aertical position or 

 with the head considerably higher than the tail, that graA ity may assist the flow of eggs. 



It was at first thought nece.-^-^ary — and the practice still obtains at some stations — 

 to bleed the fish either by cutting off the head or tiiil before making the incision. 

 Experimentatir)n, however, has conclusively demonstrated that no ad\antage results 

 from this procedure, as the few drops of blood that may occasionally fall into a pan of 

 eggs result in no harm. The extra labor involved in bleeding may therefore be 

 dispensed with entirely. 



When taken by the method of incision the eggs are of greatly improved quality; 

 there is no straining or rupture of good eggs as is ine\ itably the result when heavy 

 hand pressure i.s exerted: no unripe eggs are torn from the oAarios; and at the same 

 time there is no waste of good eggs left enfolded in the organs, as is certain to be the 

 case in stripping by hand. The improvement in (juality is from 5 to 10 per cent and 

 the sa\ ing m labor, too, is of noteworthy consideration. 



The taking of Paoific salmon eggs by incision marks so distinct an advance in fish 

 culture that it is no longer permissible to continue the obsolete method of stripping 

 by hand. 



FERTILIZING THE EGGS. & 



In impregnating the eirgs tho main object is to bring the milt and the o^gf^ together 

 as (luickly as pop.sible after they have left the fish. By some persons a little water 

 is considered desirable to give greater acti\ity to the milt, but if left more than a 

 minute in the water tliere is a decided loss of fertilizing power. The eggs do not 

 suffer so quickly from immersion in water. The absorbing property which they 

 po88e.«s when they first leave the parent fish, and which attracts to themicropyle the 

 spermatozoa, lasts several minutes, but it is not prudent to loaxc the eggs in the water 

 a moment lonirer than is nece-ssary before adding tlio milt. 



The addition of the water is not essential in a good impregnation: in some instances 

 better results are secured without the use of water and, after all, if the main object 

 is secured, of bringing the milt and the eggs together with the slightest possible delay 

 after they leave the fish, it makes very little difference whether water is used or not. 

 The milt retains its fertilizing power several davs when kept from air and water, and 

 impregnation can be effected between fishes widely separated by merely forwarding 

 the milt properly sealed. At Baird impregnation by the dry method, which has 

 always been followed there, has resulted in the fertilization of about 90 per cent of the 

 eggs so treated. 



The Ru.ssian or dry method of impregnating eggs consists simply in taking both the 

 eggs and the milt in a moist pan. It may be urged as an objection to this method 

 that the eggs will be injured by striking against the pan, but it is a fact that although 

 the same eggs would be destroyed by the concus.sion a week later, or even 24 hours 

 later, they do not suffer in the least from it at the moment of extrusion from the fish. 



It was at one time considered an important question whether the eggs or milt should 

 be taken first, but with the dry method it makes no difference, as, either way, bf)th 

 eggs and milt remain operative long enough for all practical purposes of impregnation. 



" Fi.sh Culture in Alaska, by Ward T. Bower. In Alaska Fi.slierie.s and Fur Industries in 1911, by 

 B. W. Evprmann. U. S. Unreaii of Fisheries Document No. TtiO, pp. SO, 81. Washlncton, 1912. 



»A Manual of Fish-culturo, Based on the Methods of the U. S. Commisalon of Fish and Fishorias, 

 revised edition, pp. 10-12. Washington, I9!)0. 



