KARNELLA: SYSTEMATIC STATUS OF MERLUCCIUS 



relative length of the paired fins were the main 

 criteria used by Ginsburg (1954) for recognizing 

 the Gulf population as a distinct species, M. 

 magnoculus. These differences, however, were 

 minor. More importantly the material used in 

 his study did not adequately represent either 

 the Atlantic or Gulf population. Thirty of thirty- 

 eight specimens from the Atlantic were taken 

 off Long Island, N.Y., and all 32 of the speci- 

 mens from the Gulf of Mexico came from north 

 of lat 26°N. Ginsburg was not able to make 

 a valid comparison of the Atlantic and Gulf pop- 

 ulations with the limited material available to 

 him. 



HEAD LENGTH 



Ginsburg (1954) listed the range of head 

 length taken as a percent of standard length 

 as 27.3-81.3 for M. albidus and 29.6-31.3 for 

 M. magnoculus but gave no mean values. 

 Average values calculated from the data in 

 Table 8 in Ginsburg (1954) are 28.7 for M. 

 albidus and 30.6 for M. magnoculus. The spec- 

 imens from the Atlantic and Caribbean popu- 

 lations examined in this study, had a range of 

 26.4-32.9 and a mean of 29.0, while the Gulf 



population had a range of 27.3-31.3 with a mean 

 of 29.7. As can be seen from Table 1 the head 

 length expressed as a percent of standard length 

 is fairly uniform over the entire geographic 

 area represented in this study. 



Table 1. — Head length as a percent of standard length 

 for the Atlantic and Gulf populations. 



Although the Gulf population does have a 

 slightly larger head, degree of difference between 

 the two populations reported by Ginsburg is un- 

 supported by the present data. The two popu- 

 lations are not separable on the basis of relative 

 length. 



Ginsburg also stated that growth of the head 

 was allometric. The present data indicate that 

 growth of the head is isometric (see Figure 2). 



200 r 



150 



z 



iOO- 



55 



200 



500 



600 



Figure 2. — Gulf (squares) and Atlantic (circles) populations: relation of head 



length to standard length. 



85 



