206 



BULLETIN OF THE BUREAU OF FISHERIES 



old and in their third May, June or July, depending on whether they are early or 

 late spawners, but that some delay until a year older, should they have hatched late 

 in the season or have grown slowly because of unfavorable surroundings of any sort. 

 Once they have matured, no doubt they spawn annually throughout life as do 

 other sea fish. 



Proportions of the sexes. — In American waters males have usually been described 

 as predominating largely over the females, 69 but as there seems no great disparity 

 between the sexes off Sweden 60 this point calls for renewed study. 



Breeding habits. — Mackerel spawn off the American coast from the latitude of 

 Cape Hatteras to the Gulf of St. Lawrence; but although both ripe and spent fish 

 have been reported from the southern spring fishery, and while mackerel have long 

 been known to spawn regularly off southern New England, a much greater produc- 

 tion of mackerel eggs takes place east and north than west and south of Cape Cod, 

 with the Gulf of St. Lawrence far the most productive nursery for this fish. The 

 scanty data yet available point to the Gulf of Maine as second to it in importance 

 as a spawning ground, but whether mackerel spawn to any extent off the outer 

 coast of Nova Scotia is still to be learned. 



Spawning season. — Spawning mackerel have long been very familiar objects 

 to the fishermen, the purse seiners often taking whole schools of fish in that state, 

 and it is now well established that all mackerel that are old enough to breed are 

 close to sexual maturity when they come to the surface in spring or early summer 

 (according to locality). 61 



In the Guff of Maine the first adult fish caught are usually still hard, but 

 they are soon taken with the eggs or milt running. The last half of May and the 

 month of June cover the height of the spawning season in the Massachusetts Bay 

 region, though occasional ripe fish are taken there as late as the 1st of August. The 

 mackerel spawn at about this same season off Casco Bay, where the largest run of 

 spawning fish was about the middle of June in 1897, with the proportion of spent 

 fish steadily increasing through July, which may be taken as descriptive of condi- 

 tions over the Gulf of Maine as a whole. Our own mackerel-egg records are con- 

 sistent with this, the earliest being for May 6, the richest in June as listed below, in 

 tow net hauls at different localities during the spawning season in 1915: 



» Smith. Report, U. S. Commissioner of Fish and Fisheries, 1900 (1901), p. 128. 



"° Nilsson. Publications de Circonstance No. 69, Conseil Permanent International pour l'Exploration de la Mer, Vol. XVI, 

 1914. 



•> J. P. Moore (1899) gives observations on the sexual state of the fish caught off Casco Bay in 1897 and results of tow nettings 

 for eggs. 



