AGE AND GROWTH 



Pinfish were aged by using length- frequency 

 data and by examination of scales. Length fre- 

 quencies have been used to age pinfish (Caldwell, 

 1957) but scales have not. Pinfish from the two 

 stations were of similar lengths ; therefore, length- 

 frequency data for the stations were pooled (fig. 

 2). The bimodal length- frequency distribution in- 

 dicates at least 2 year-classes of jDinfish. 



Average length of pinfish at annulus formation, 

 as determined by scale measurements, was similar 

 to the average length of fish measured in early 

 spring. Most of the annuli formed in April of both 

 196J: and 1&65. The percentage of yearling fish that 

 showed an annulus in different months in 1964 and 

 1965 (data combined) were as follows (number of 



fish in parentheses) : January — 12 percent (57) ; 

 February — 13 percent (85) ; March — percent 

 (2); and early May — 100 percent (42). Back- 

 calculation of fish lengths showed that the 1963 

 and 1964 year classes formed a year-mark at aver- 

 age lengths of 61 and 78 mm., respectively. Fish 

 from tliese year classes were at this size as yearlings 

 in March or April. The average length of fish 

 entering their tliird year of life was 127 mm. (15 

 fish) at the time of annulus formation. 



The average size of pinfish varied during the 

 different years (table 3). Yearly differences in 

 average size result from a number of factors such 

 as differences in hatching time and growth rate. 

 Standard lengths of fish caught by trawling and 

 seining during the study were 13 to 152 mm.; fish 



>- 

 o 



z 



UJ 



3 



o 



UJ 

 DC 

 li. 



o 



IT 



30 

 10 



30 



10 

 30 

 10 



40 

 20 



I 30 



UJ 



O 10 

 o 



UJ 



u- 10 



^20 



)^ 10 

 oc 



UJ 



Q. 20 



10 



20 

 10 



30 50 70 90 110 

 STANDARD LENGTH (MM.) 



■i I 



FEBRUARY 



I96S 



N=33 



MARCH 1965 



MAY (EARLY) 1965 

 N=2A52 



MAY (LATE) 1965 

 N = 3|972 



SEPTEMBER 1965 

 N = 1,723 



OCTOBER 1965 

 N = l/»20 



DECEMBER (EARLY) 1965 

 N=262 



10 30 ' 50 70 90 

 STANDARD LENGTH (MM.) 



150 



Figure 2.- 



-Length-freqnency distribution of pinfish caught in the lower Pensacola Estuary at stations I and II, 



1963-65. 



LIFE HISTORIES OF PINFISH AND ATLANTIC CROAKER 



139 



