402 BULLETIN OF THE BUBEAU OF FISHEBIES 



the rate of growth of the pollock, and Mavor (1918, p. Ill) has done the like for fish 

 caught in the Bay of Fundy. Judging from his data and from the size of the fry 

 caught at Woods Hole in spring, pollock hatched in the Gulf of Maine in midwinter 

 are about 1 to 2 inches long the following spring, growing to 3 to 5 inches by late 

 summer. They will average about 5 or 6 inches by the second spring (their scales 

 then showing one winter ring) , about 12 inches the third spring, and 14 J^ inches by 

 the following midsummer when 2)4, years old — that is to say, the little harbor pollock 

 of 6 to 8 inches are in their second summer. Bay of Fundy fish in their fourth sum- 

 mer — that is, when 3H years old — are 14 to 18^2 inches long, and the scales of the few 

 older fish that Mavor examined indicated an average length of about 23 inches at 43^ 

 years, 25 inches at 5% years, and 27 inches at 6J/2 years. These sizes are somewhat 

 larger than averages given by Damas for European fish of corresponding ages, but 

 the difference is so small that it is safe to apply the European figures to older Gulf 

 of Maine fish for which Mavor gives no data. Accordingly, we might expect the 

 American pollock to average about 28 inches at 7^2 years, about 29 inches at 8K 

 years, 30 inches at 9}/£ years, about 31 inches at 12 years, about 32 inches at 13 years, 

 and 33 inches at 14 years. Fish of 3 feet and upward are therefore of a very re- 

 spectable age, and the oldest recorded by Damas among thousands examined was 

 in its nineteenth year. The annual rate of growth works out to about 6 inches 

 yearly for the first two years, slowing to about 4 inches for the next two or three 

 years. Fish 5 to 10 years old annually increase about 1J^ to 2 inches in length, 

 after which they grow still more slowly. In European seas pollock grow faster in 

 the southern part of their range than in the northern part, but whether this 

 applies equally to the American fish is yet to be learned. 



The age at which Gulf of Maine fish first mature is not known, but it is probably 

 at the same size as in Norwegian waters, where some may ripen as small as 6 

 inches, and most of them by the time they are 1 )4, f ee t long — that is, 3 years old. All 

 fish of a length of 2 feet and more in summer have spawned at least once. 



It may be interesting to note in passing that the relative frequencies of fish of 

 different sizes which Mavor examined point to the year class of 1909 as dominating 

 the catches of Bay of Fundy pollock during 1914, 1915, and 1916. 



Breeding habits. — The chief spawning ground for pollock within the Gulf of 

 Maine is at the mouth of Massachusetts Bay, particularly along the outer (eastern) 

 slope of Stellwagen Bank and on the broken bottom southeast of Gloucester. Accord- 

 ing to Mr. Corliss, superintendent of the Gloucester hatchery, " the bulk of the 

 pollock eggs collected for this [Gloucester] station are taken on the grounds lying 12 

 to 25 miles southeast of Eastern Point Light, the most prolific ground being IS miles 

 offshore." The gill-netters also catch an abundance of ripe fish between Cape Ann 

 and the Isles of Shoals, where breeding pollock congregate in such abundance as to 

 support a lucrative fishery. 



In some years many pollock spawn, and large quantities of their eggs have been 

 collected for the hatchery, right up to Boston Lightship in the inner part of Massa- 

 chusetts Bay, though this is not a regular annual event. But few spawning pollock 

 are caught in the Gulf south of the Massachusetts Bay region, and we find no report 

 of it as breeding anywhere west of Cape Cod although fry of the winter's hatch 



