MACKEREL INVESTIGATIONS IN 1897. 21 



The results of experiments indicate no form of apparatus better for 

 the first two days of development than the usual tidal boxes, provided 

 the sides are smooth, preferably of glass or enamel, and provided that 

 the screens are kept free of any deleterious substances. For the later 

 days of development and for the. fry after hatching a higher density 

 and greater purity of water and a form of apparatus that insures a 

 better circulation and keeps the ovum in suspension without undue 

 agitation is indicated. 



Being very delicate and sensitive to physical injury and the presence 

 of deleterious substances, the eggs should be handled as little as possi- 

 ble. A relatively small number should be placed in one receptacle, not 

 more than would form a single layer on the surface (Mr. Corliss's opinion 

 on this point differs from mine, he claiming to have had equal success 

 with large and small numbers), and especially the hatching apparatus 

 should be kept as free as possible from decaying organic matter or 

 other contaminating substances. 



RECOMMENDATIONS. 



The experience of the past few years seems to render it sufficiently 

 obvious that unless some very different conditions obtain in future there 

 is little to be hoped for from the methods of propagating the mackerel 

 now in vogue. The few millions of eggs annually secured are so insig- 

 nificant in comparison with the vast numbers which must be produced 

 naturally that even if all were hatched the fry resulting would be a 

 mere drop in the ocean. 



It is well known that the purse-seine fishermen operating some miles 

 offshore frequently secure whole schools of spawning mackerel, from 

 which the eggs run so freely that decks of fishing vessels become 

 literally covered with those which have accidentally escaped. This 

 circumstance, coupled with the before-mentioned fact of the readiness 

 with which fertilization can be accomplished, leads to the following 

 suggestion, which I recommend as a guide toward a tentative policy of 

 the Fish Commission during the progress of further investigations: 



The captains of the fishing schooners should be asked to cooperate 

 upon such terms as may be agreed upon, to the end that when such 

 spawning schools of mackerel are met with the fish should be immedi- 

 ately stripped, the ova and sperm mixed, and, after permitting a few 

 minutes to insure fertilization, turned overboard to undergo their devel- 

 opment amid the natural surroundings from which they were taken. In 

 this way, especially when such schools were taken in the late afternoon 

 or at night, vast numbers of fertilized and healthy eggs could be liber- 

 ated under conditions which have been previously indicated as those 

 most favorable to their growth. 



The work of stripping and impregnation can be accomplished so 

 simply and quickly that it would not materially interfere with the regular 

 duties of fishing, and I have no doubt that the more intelligent fisher- 

 men, particularly in view of some small consideration, could accomplish 



