209 
while in the North Sea immature female fish of 17” have 
been observed. In the male sexual maturity is first 
attained at a lesser size than in the female; in Danish 
waters ripe males 7 inches long, and in the North Sea 
9 inches occur. The most convenient size* for purposes 
of legislation is that lowest size at which as many Plaice 
are mature as immature. This is the average size of first 
maturity, and it is of course lower in the male than in the 
female. In the northern part of the North Sea the female 
reaches maturity for the first time on the average at 155 
inches, and the male at 124 inches. In the southern part 
of the North Sea these sizes are 134 inches for the female 
and 101 for the male. In the English Channel Cunning- 
ham found that nearly all Plaice were mature at 15 inches, 
and in the North Sea Holt found that at 17 inches nearly 
all the fish observed were mature. In the Danish seas 
much lower sizes than these have been estimated by 
Petersen.t Thus the average sizes at which Plaice first 
become mature are 10 inches in the Baltic, 11 inches in 
the Lesser Belt and 12-13 inches in the Kattegat. In the 
Irish Sea the smallest mature female observed was 13 
inches in length, and the largest immature female 19 
inches. The smallest mature male obtained was 105 
inches long, and the largest immature male 15 inches. 
Sufficient fish have not been examined in this district to 
enable satisfactory average sizes for the first maturity to 
be established. 
It is probable that the Plaice spawns every year after 
sexual maturity is attained, but there is no certain 
evidence on this point, nor is it known what are the yearly 
increments of growth after the third year of life. In the 
*See Kyle, 18th An. Rep. Scottish Fish. Bd., Pt. iii., p. 189, 1900, for 
a discussion of this subject. 
+ 4th Report of the Danish Biol. Station, 1894, p. 3. 
R 
