8b. Pectoral fin narrow, its tip pointed. Tips of first dorsal fin and first anal fin 



pointed Striped marlin, Tetrapturus audax (Phillipi), Figure 1H 



9a. Pectoral fin can be folded back against side of body 



10 



9b. Pectoral fin rigid cannot be folded back against side of body 



.Black marlin, Makaira indica (Cuvier), Figure IK 



10a. Lateral line system with simple loops 



Indo-Pacific blue marlin, Makaira mazara Jordan and Snyder, Figure II 



10b. Lateral line system reticulated 



.Atlantic blue marlin, Makaira nigricans Lacepede, Figure 1J 



CLASSIFICATION PROBLEMS 



WITH SOME SPECIES 



OF BILLFISHES 



While re-examining the study of the world bill- 

 fishes made by Nakamura, et al. (1968), C.L. Hubbs 

 (personal communcation) has made me aware of the 

 critical opinions expressed by some researchers 

 about this work. Hubbs stated his views as follows: 

 "Two of the main problems involve the name we 

 should use for California species oilstiophorus and 

 Makaira. I see that you have definitely listed sepa- 

 rately Istiophorus platypterus and /. albicans and 

 also Makaira nigricans and M. mazara. In recent 

 correspondence with Dr. Robins I find that he feels 

 that these two pairs of species, as you recognize 

 them, are either identical or only subspecifically 

 separable. In both cases he seems to find that the 

 differences are rather definitely related to the fact 

 that the species grow larger in the eastern Pacific 

 than they do in the Atlantic. In the case of the two 

 blue marlins, he says that he has found indications 

 that the degree of network of the lateral line system 

 and the differences in the osteology that have been 

 used are both dependent on size of fish, but that 

 probably does not explain all the differences." 



In Nakamura, etal. (1968), both /. platypterus and 

 /. albicans were recognized only tentatively as valid 

 species; principally because data were lacking to 

 establish with certainty whether the two forms were 

 conspecific, subspecies, or distinct species. While 

 data are still inadequate, I now feel that both forms 

 can be recognized as subspecies. I consider that 

 some distinctions noted between these two forms, 

 especially in species of 90 cm, could be referable to 

 subspecific status. These features include differ- 

 ences in maximum body length attained, relative 

 length of pectoral fin (Fig. 2) and spread of caudal fin 



50 



.<"' 



100 200 



BODY LENGTH 



Figure 2. — Relationships between pectoral fin and body 

 length in sailfish. Open circles show data from the Atlantic 

 sailfish and solid circles show data from the Indo-Pacific 

 sailfish. Data from Vick (1963) and Royce (1957) are in- 

 cluded. 



(Fig. 3). Morrow and Harbo (1969) reported that 

 analysis of morphometric and meristic characters of 

 sailfish from various localities in the Atlantic, 

 Pacific, and Indian Oceans indicated that the genus 

 is monotypic, composed of a single species that 

 shows remarkably little variation in the characters 

 examined. Further study of anatomical, ecological, 

 behavioral, and other biological aspects is necessary 

 to clarify the problems of speciation in sailfish. Until 

 this is achieved, I retain the use of/, platypterus for 

 the Indo-Pacific sailfish and /. albicans for the At- 

 lantic sailfish. 



I believe that both M. mazara and M. nigricans 

 are distinct species chiefly because of differences in 

 the pattern of the lateral line system. In the speci- 

 mens I examined, the differences were constant with 

 growth (Fig. 4). It should be pointed out, however, 

 that the lateral line systems of individuals larger than 



48 



