THE SMELTS 
347 
prolific. Notwithstanding the adversities they encounter, their rapid migration, 
whether active or passive, is necessary for the survival; for the conditions of their 
birthplaces do not afford the requisite quantity of suitable food, which is to be found 
only in more open or tidal waters. 
Observations by Ehrenbaum (1894) upon the smelts of the Elbe River showed 
that the newly hatched fry were 5 to 6 millimeters (about 34 to nearly 34 inch) in 
length. They were found to attain from a little over 0.55 to 0.7 of an inch in length 
in one month. In three months they reached 1.25 to 1.45 inches. In five months 
the lengths were found to range from 1.73 to 2.36 inches. In the month of August 
the range of length was from 1.57 to about 2 inches. It was determined also that 
the smallest mature smelt was about 4 inches long and 2 years of age, but many 
larger fish were found to be immature. 
According to Sundevall, on their first exclusion the fry of Swedish smelt are 5 
millimeters long and perfectly transparent; they are characterized by the univer- 
sally backward position of the vitelline sac (yolk sac) , the distance between it and 
the insertion of the pectoral fins being more than half of that between these fins and 
the tip of the snout. In August, according to Yarrel (1836), the English smelt has 
attained a length of 75 millimeters (nearly 3 inches). 
Cunningham stated that the larvae of smelts ( 0 . eperlanus ) have been kept alive 
for 15 days after hatching in an aquarium. On the sixth day by the growth of the 
ower jaw the mouth had become terminal and the yolk was nearly all gone, but the 
fins had not begun to appear. The larva at this age was 6.3 millimeters long (34 inch) . 
The youngest larvae captured in the river were taken on the 5th to 8th of May and 
were 6 to 8 millimeters long (the largest nearly 34 inch), and had begun to feed on 
the minute Crustacea, called “ copepods,” the usual food of young fishes. The larvae 
were extremely abundant in the estuary of the Elbe. A small net only 2 feet 8 inches 
across the opening placed in the current for a quarter of an hour captured on one 
occasion (May 28) a number calculated to be 107,000. These specimens were 14 
to 20 millimeters long (three-fifths to four-fifths inch) and were still very trans- 
parent, but the first dorsal and the ventral fins had appeared. These larvae were still 
very slender in proportion to their length and were remarkable for the great size of the 
air bladder. In the middle of June the little fish were four-fifths inch to 1-^ inches 
long and had nearly reached the form and character of the perfect smelt. They were 
still, however, transparent and without scales and silvery coat. Even in August the 
young smelts, now 1-^ inches to \% inches although more pigmented and less trans- 
parent, had not acquired their scales and silvery garment. The development of these 
last characters of the perfect fish takes place in September and October, when the 
young are 2 inches to 2.4 inches long. 
In 1913 Masterman, from a study of the scales of British fish, indicated that 
smelts 1 year old averaged 4.48 inches, 2 years old 7.24 inches, 3 years old 7.55 
inches, and 4 years old 8.85 inches. From the foregoing figures, then, it may be con- 
cluded with a fair degree of safety that the Atlantic smelt of American rivers spawn 
at the end of the second year and may average at that age between 6 and 7 inches. 
According to Cunningham “ after October the smelt, young and old, descend 
toward the sea, and return toward fresh water at the end of February and in March. 
