214 Part III.—Twenty-fourth Annual Report 
zones of the vertebra, he says “‘one may count three at one time, and at 
the next attempt there seem to be four or five, and the total number 
always remains doubtful and uncertain.” He found that tranverse slices 
of the otoliths showed the markings much better, and he chiefly used 
them in determining the age of the specimens of cod he studied. Here 
are some of the results, though doubt is expressed as to the certainty of 
the determination in some cases :— 
Caught 9th November. i Caught 9th March. 
| Length. Probable Age. || Length. Probable Age. 
Cm. |Inches || Cm. | Inches. 
47 184 about 24 years || 24:3 | 10 2 years 
54 212 | Shs | 80°5 122 Di ss 
64 252 Sh-5, pail owe — 12 2 sae, 
possibly 28 ,, || 835 | 132 Dine aes 
73 291 BE | 44:3 | 173 Beh 
| | 45°6 | 184 Seis 
| 67:5 | 27 AS a 
According to these later results, Mr. Cunningham says, the cod at two 
years of age is 10 to 13 or 14 inches in length, at three years 17 to 19 
inches, at four years 27 inches; but, he adds, it would require the 
examination of a large number of specimens to ascertain the average and 
range of sizes at these ages. So far as these results go, they are in 
agreement with my own derived from the method of measuring the fishes. 
Lately Dr. S, Strodtmann published a paper on the spawning and migra- 
tions of fish in the Baltic, which contains some observations on the growth 
of young cod, taken in Travemiinder Bucht.* 
A series numbering 555, taken on 15th October, 1904, measured from 
Sem. to 16cm. (2-63 inches), the average being 10-0cm., or barely 4 
inches. A month later, November 14th, 743 ranged from 5cm. to 15cm., 
the average being 10‘5em. On December 12th, 333 measured from 7em. 
to 19cm (22-73 inches), the average being 13:5, or 58 inches. At the 
beginning of March in the following year they ranged from 9cm. to 
17cm., and numbered 75, the average size being 12°8cm., and at the 
beginning of April 123 ranged from 9cm. to 17cm., the average being 
13cm., or 53 inches. These results agree closely with my own. On 
September 9th, 84 measured between 16cm. and 30cm. (63-11? inches), 
the average being 21-5cm. (84 inches), which is also near what will be 
found in the Tables appended. 
It will be noticed that the young cod in December are rather larger 
than in either March or April, while from November to December they 
appear to have grown 3cm., which Dr. Strodtmann considers to be 
improbable at that season. In the course of the summer they increased 
by 8:5cm., or 33 inches. He compares the growth at the place indicated 
with the growth of young cod at Biisum, on the North Sea, and shows 
that the latter at the beginning of October had a greater range of size and 
a larger average size than in the Baltic at the middle of the month. The 
Baltic fish ranged from 5em. to 15cm., according to the diagram, the 
average being 10cm., while the North Sea cod ranged from 5em. to 16cm. 
or 17cm., and the average was 12cm. or 13cm. (43-53 inches. At 
Aberdeen in the same month the average was 12cm. also. 
In the Tables appended to this paper will be found the measurements 
of the cod I have dealt with, grouped into centimetres, and the following 
*Laichen und Wandern der Ostseefische, p. 209. 
