108 
BULLETIN OF THE BUREAU OF FISHERIES 
The number of larvae, 5 millimeters and less in length, in the collection is too 
small to show the vertical distribution. Since the eggs are pelagic, the larvae would 
be expected to remain at or near the surface, at least, until the yolk is absorbed. 
The yolk sac contains an oil globule which persists until virtually all the yolk is 
absorbed (Welsh and Breder, 1923, p. 153, fig. 10). The oil globule almost cer- 
tainly would keep the newly hatched fish at or near the surface. However, the indi- 
cations are that the young fish in part, at least, go to the bottom very early, as the 
25 specimens at hand having a range in 
length of 1.5 15 to 5.0 millimeters were all 
taken in bottom hauls. The larger ones 
undoubtedly stay principally on the 
bottom, as all except 2 of a total catch of 
270 specimens, 6 to 10 millimeters long, 
were caught in bottom hauls. 
It is stated elsewhere (p. 102) that the 
large fish leave the shallow waters during 
cold weather, whereas the smaller ones are 
more apt to remain. The young of the 
0- class were taken throughout the winter. 
It seems significant, however, that the larger 
individuals are missing during the coldest 
months (see table 5), indicating that the 
largest young of the year probably follow 
the adults to a more agreeable habitat. 
GROWTH 
The study of the rate of growth was 
limited chiefly to the 0-class. The tables 
and graph presented herewith show quite 
conclusively that the rate of growth is 
very rapid during the first summer. The 
distinction between the 0-class and the 
1- class is not very distinct after July, as 
some overlapping takes place, and it is prob- 
able that a few specimens may have been 
wrongly assigned in table 5. However, 
the specimens improperly placed are so few that the averages cannot be affected 
importantly, and therefore may be accepted as approximately correct. 
The largest individuals of the 0-class, as shown by the accompanying tables 
and graph, already had attained a length of 215 to 220 millimeters (8)4 to 8% inches) 
in October, and the average length of 914 fish measured was 150.4 millimeters (6 
inches). In December a few individuals, apparently belonging to the 0-class, had 
attained a length as great as 220 to 233 millimeters ( 8 % to 9 % inches), and the average 
15 Specimens only 1.5 millimeters long in the present collection do not retain a yolk sac. Much shrinkage takes place in larval 
fishes during the hardening process if alcohol and formalin is used, as with the specimens at hand. Judging from the degree of 
shrinkage known to occur in some other species, as in the pigfish ( Osthopristes chrysopterus), for example, it seems probable that 
the specimens of trout 1.5 millimeters long may have had a length of 2.5 millimeters before preservation. Welsh and Breder (1923, 
p. 153, fig. 10) show that the yolk sac is very small in live or fresh larvae when 2.2 millimeters long, and it would be expected to 
disappear very soon afterward. 
Figure 41. — Growth of Cynoscion regalis during first year 
or so of life. Solid line, average size; dot and dash line, 
maximum size; broken line, minimum size. (Graph based 
on table 5.) 
