500 - 



-J 400 



o 



z 



UJ 



< 



0^ 



>■ 

 a. 



(3 



z 



ILI 



r 



300 



200 



100 



'-'V- 



y=4 274038X 



 ■»■■■■■■ '' ^ o/ooocooo;' 

 OOP oopq 00 00 o P I 



20 30 40 



• /.* • y=-320.44H0.42x 



50 



60 



70 



80 



FORK LENGTH 



(MM.) 



Figure 11. — Length of anterior alimentary tract and of total tract in relation to fork 

 length of young Atlantic menhaden. Open circles represent group means of anterior 

 tract measurements of 138 specimens; solid circles represent group means of the 

 total tract length. The regression line for the 19- to 30-mm. fork length range was 

 computed from measurements of 48 specimens and that for the 31- to 75-mm. fork 

 length range from measurements of 90 specimens. 



and the long coiled intestine increases the sur- 

 face area for secretion and absorption. 



Table 8. — Pyloric caeca counts of young Atlantic 

 menhaden 



LABORATORY STUDIES 



We demonstrated that qualitative differences 

 in the diet of young Atlantic menhaden were 

 associated with changes in the gill raker- 

 alimentary tract complex during metamorpho- 

 sis, but we still did not know the quantities of 

 food they needed for growth. The high inci- 

 dence of empty or partially filled alimentary 

 tracts in larvae captured in Indian River, Del., 

 suggested that these quantities were small. 

 Peck (1894) and Breder (1959) had described 

 the feeding behavior of juveniles sufficiently 

 for our needs, but we still did not know how 

 larvae and prejuveniles fed nor if they could 



504 



U.S. FISH AND WILDLIFE SERVICE 



