60 



5 

 5 



40 



< 



z 

 < 



I 



z 



y 20 

 > 



"T 1 1 1 1 1 1 I I r 



± 



_L 



20 



40 60 80 



TRUNK LENGTH (MM.) 



100 



120 



FiouKE 12.— Relation of the distance pelvic fin-anal fin to trunk length in sailfish from the western Atlantic. 



what with body part and tliat some parts have little 

 or no inflection. Figure 13, which illustrates the 

 regression of trunk length on body length, is in- 

 cluded to show that tliis relation is rectilinear 

 throughout the size range; the calculated regres- 

 sion line for specimens with trunk length greater 

 than 62 mm. has the same slope (b) and is merely 

 an extension of that for smaller fish. 



Subsequent to preparation of plots of data and 

 calculation of regression lines for western Atlantic 

 sailfish, I obtained measurements from 34 eastern 

 Atlantic fish and plotted them on graphs. The data 

 from the eastern Atlantic are too meager, however, 

 for making calculations of regressions — the num- 

 ber of specimens is too small and the size distribu- 

 tion is poor. Because the greater numbers of west- 

 ern Atlantic specimens might possibly hide diifer- 

 ences between the two groups if the data were com- 

 bined, I plotted them separately on the same 

 graph, distinguishing the two groups. I shall limit 

 my conunents to dift'erences this simple comjjarison 

 suggests. 



The individual plots of data for eastern Atlantic 

 sailfish generally lie within the ranges for fish from 

 the western Atlantic for eye diameter, body depth, 

 pelvic fin length, and distance from pelvic fin to 



anal fin ; these data are, therefore, not shown on 

 the figures showing these relations (figs. 8, 9, 11, 

 and 12, respectively). Measurements of snout 

 length, liead length, and pectoral fin length, how- 

 ever, generally lie higher on the graphs for fish 

 from the eastern Atlantic than for those from the 

 western Atlantic (figs. 6, 7, and 10). The longer 

 head (fig. 6) is attributable to the generally longer 

 snout (fig. 7). The pectoral fin is also generally 

 longer in eastern Atlantic sailfish (fig. 10). 



ACKNOWLEDGMENTS 



Staff members of BCF Biological Laboratory, 

 Brunswick, Ga., helped collect western Atlantic 

 specimens, made X-ray photographs, and cleared 

 and stained study material ; they also prepared il- 

 lustrations and reviewed the manuscript. Person- 

 nel of BCF Exploratory Fishing and (iear Re- 

 search Station, Brunswick, Ga., also helped collect 

 western Atlantic specimens. George C. Miller, of 

 BCF Tropical Atlantic Biological Laboratory, 

 Miami, Fla,, made available eastern Atlantic speci- 

 mens collected off west Africa. Grady W. Reinert 

 prepared illustrations, and Elbert H. Ahlstrom, 

 Donald P. de Sylva, and R. Michael Laurs re- 

 viewed the manuscript. 



188 



U.S. FISH AND WILDLIFE SERVICE 



