30 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



should naturally expect the advent of grilse early in July in considerable 

 numbers; but some of the weirs are often kept in operation until the 

 middle or last of July, and sometimes even through August, when they 

 take menhaden ; but no grilse enter them. During the latter part of the 

 summer the water at the several falls between Bangor and Oldtown is 

 generally at a low stage, and the attempt of grilse, even in sma.ll num- 

 bers, to ascend the river could hardlj^ fail to be frequently detected. 

 A similar state of things exists in the Kennebec. There is no escaping 

 the conclusion that the great run of grilse, which is so prominent a fea- 

 ture in the history of the salmon of northern rivers, is almost entirely 

 wanting in the rivers of the United States. It by no means follows from 

 this that our salmon do not pass through the same phases of growth, or 

 that the growth is more rapid, but merely that when in the grilse stage 

 they generally lack the instinct that impels their more northern relatives 

 to seek fresh water. 



Of the characteristics of grilse, as ascertained in the rivers they 

 frequent, it will be sufficient to say that they exhibit to a great degree 

 the characteristics of the adult; that the main external differences 

 are a shorter head, slenderer form, and a difference in the color and 

 markings; that they are remarkably active and agile, leaping to great 

 heights; that the male is sexually well developed and mates with the 

 adult, but that the female is immature, and that, like the adult, they 

 abstain from food and consequently lose flesh during their stay in fresh 

 water. 



The next stage of life of the fish is that of the adult salmon, and this 

 is the stage at which, with the exceptions indicated above, the Atlantic 

 salmon first ascends the rivers of the United States. Assuming that it 

 relinquished the rivers for the sea at the age of two years, being then 

 asmolt, it has been absent two years, and it is now four years or a little 

 more since it burst the shell. This estimate of age is based on the 

 observations ftiade by the Massachusetts commissioners of fisheries 

 on the return of salmon to the Merrimac River, which plainly estab- 

 lished the fact that the entire period between the hatching of the fry 

 and the return of the adult to the rivers is about four years. Whether 

 the same rule holds in other jSTew England rivers can not as yet be 

 established, owing to deficient data, but the presumption is in favor of 

 that conclusion. In Canadian rivers the same jieriod of growth appears 

 to be the universal rule, at least as far north as the St. Lawrence River. 

 Statistics of the catch of salmon for many years in eighteen separate 

 districts, showing many fluctuations, exhibit a remarkable tendency of 

 the figures to arrange themselves in periods of five years; thus, the 

 year 1875 having been a year of small catch of salmon, it also appears 

 in most of the districts that the next year of abnormally small catch 

 was 1880. Now, the eggs laid in 1875 would hatch in 1876, and the 

 young hatched at that time would be grown in 1880, requiring thus 

 four years from hatching to maturity, just as on the Merrimac. It 

 would seem no other interpretation can be put upon the statistics. 



