FISHES OF THE GULF OF MAINE 99 



thereafter as long as they live. In Norwegian waters, too, a few spawn at 3, many 

 at 4, and the majority at 5 years of age and upwards; some few, indeed, not until 

 6 years. Herring as old as 20 years have been seen, and they may live even longer. 



Success of reproduction. — The maintenance of the stock of any fish and its 

 relative abundance from year to year depends less on how many fish spawn in any 

 locality than on how many of the resultant fry survive. The many age analyses 

 made of herring of different sizes and from various seas have proven that while in 

 some years a very large crop of young fish is produced, in others hardly any are 

 obtained even in favorable nurseries. Apparently this applies more to the northern 

 than to the southern breeding grounds — to some extent, however, to all — the result 

 being that the fish spawned in some one favorable breeding season may dominate 

 the herring schools over large areas for many years or until another good breeding 

 year produces another large crop. In Norwegian waters, for example, few herring 

 were raised in 1903 but so many were produced in 1904 that fish of that year pre- 

 dominated in the catches for the next six years at least. 



Unfortunately information along this line is yet unavailable from the Gulf 

 of Maine. 93 No doubt similar fluctuations occur in the crop there, too, for 

 Lea 94 found that fully 50 per cent of the herring taken at West Ardoise and 

 Lockport on the outer coast of Nova Scotia in 1914 belonged to the year-class 

 spawned in 1911, whereas on the west coast of Newfoundland fish hatched in 1904 

 dominated the spring catches of 1914 and 1915. Various explanations, such as 

 abundance or scarcity of microscopic plankton, favorable or unfavorable tempera- 

 ture or salinity, etc., have been proposed to account for this, all of which may enter 

 in, for while it is during the first few weeks of life that the herring is most vulnerable 

 it is also possible that the conditions under which the parent fish lived for the year 

 preceding spawning may influence the fate of the fry. Whatever the explanation, 

 the fact that such fluctuations do occur from year to year in the stock of fry reared 

 is of the greatest practical interest to all concerned with the sea fisheries, as evi- 

 dence that variations existing in the stock of herring, and consequently in the catch, 

 are due more to the success or failure of reproduction than to depletion by over 

 fishing. 



Seasonal movements of herring in the Gulf of Maine. — The life of the herring 

 may be divided, roughly, into three stages correlated with differences in distribu- 

 tion and seasonal movements. First, the young and "sardine"; second, the imma- 

 ture "fat"; and third, the mature "spawn." When the little herring reach an age 

 of about 2 years and a length of 190 to 200 mm. they begin to accumulate large 

 amounts of fat among the body tissues and viscera during their period of active 

 growth in the warm months of the year, and lose this fat in winter and at the 

 approach of sexual maturity. We can bear witness — the fact is well known to 

 fishermen — that the "fat" stage is as characteristic of American waters as of 

 European, where "fat" herring are the objects of extensive fisheries. 



Owing to the fact that most of the herring larva? hatch and pass the first couple 

 of months of their existence at a time of year (September to February) when we 



63 Herring studies had been one of Mr. Welsh's major undertakings. 

 •' Canadian Fisheries Expedition, 1914-15 (1919), p. 131, fig. 38. 



