YOUNG OF THE ATLANTIC SAILFISH, ISTIOPHORUS PLATYPTERUS' 



BY JACK W. GEHRINGER, FISHERY BIOLOGIST 



BUREAU OF COMMERCIAL FISHERIES BIOLOGICAL LABORATORY 



BRUNSWICK, GA. 31520 



ABSTRACT 



One hundred fifty-four Atlantic sailfish, 26.1 to 216 

 mm. in standard length, were dip netted on cruises of 

 the Bureau of Commercial Fisheries charter vessel 

 Silver Bay off the south Atlantic Coast of the United 

 States in 1960 and 1962. This group of specimens (larger 

 than any previously available collection of sailfish of 

 similar size) was examined to determine changes during 

 development. Thirty-four eastern Atlantic specimens 

 13.8 to 238 mm. in standard length that were dip netted 

 in 1968 on a cruise of the Bureau's vessel Undaunted 



in the Gulf of Guinea were compared with the specimens 

 from the western Atlantic. 



Five western Atlantic specimens are illustrated. Loss 

 of larval characteristics and development of fins and 

 fin rays and pigmentation are discussed. Correlations 

 of numbers of fin rays and statistics describing rela- 

 tionships of measurements of selected body parts for 

 western Atlantic specimens are presented. Principal 

 differences between eastern and western Atlantic 

 specimens are the slightly longer pectoral fin, snout, 

 and head in eastern Atlantic specimens. 



Collections of the young stages of Istiophoridae 

 that include a sufficient number of larvae and 

 juveniles for detailed studies of developmental 

 stages are rare. The literature on young Atlantic 

 sailfish, Istiophonis platypteru-s (Sliaw and Nod- 

 der),- is jjrimarily on small larvae and has infor- 

 mation on only 21 specimens longer than 25 mm. 

 SL (standard length) — (Voss, 1953, 4 specimens 

 29.5-208 mm.; Gehringer, 1957, Ifi specimens 

 27.4-101 mm.; and de Sylva, 1963, 1 specimen, 

 167 mm.). 



This paper is based primarily on a collection of 

 154 sailfish from the western Atlantic Ocean, 26.1 

 to 216 nun. SL. They were collected At dip net and 

 nightligiit stations on cruises of the BCF (Bureau 

 of Commercial Fisheries) charter vessel Silver 

 Hay off the southeastern coast of the United States 

 in June and July 1960 and September and October 

 1962. Subsequent to my examination of the west- 

 ern Atlantic specimens and preparation of a draft 

 of a manuscript describing them, I examined 34 

 specimens, 13.8 to 238 mm. SL (all but 1 over 

 25 mm. SL), collected by dip net at nightlight 

 stations on a cruise of the BCF vessel Vndmmted 



' Contribution No. 95 from the Burea\i of Commercial Fisheries 

 Biological Laboratory, Brunswick. Ga. 31520. 



-In using the name Istiophonis platyptcrua (Shaw and 

 Nodder), I follow Morrow and Harbo (1969). 



Published .Tanuar.v 1970. 



FISHERY BULLBTIN: VOL. 68, NO. 2 



in the Gulf of Guinea, ofi' the west coast of Africa, 

 in April 1968. 



For western Atlantic specimens I include 

 detailed line drawings of a developmental series, 

 statistics showing the relationships of measure- 

 ments of selected body parts, and discussions of 

 dorsal and anal fin rays and changes during their 

 development. I compare eastern and western 

 Atlantic specimens of similar size and include in 

 my discussion of western Atlantic material those 

 variations I found in eastern Atlantic material. 



METHODS AND DATA 

 MEASUREMENTS 



Measurements were made with dial calipers 

 calibrated in 0.1 -mm. units and are recorded to the 

 nearest 0.1 mm. if less than 100 mm. or to the near- 

 est millimeter if 100 nnn. or greater. 



DEFINITIONS OF TERMS 



I consider all specimens in this study to be 

 juveniles, by definition of the juvenile stage as 

 sexually immature specimens whose numbers of 

 fin rays are within the ranges for the adult. 



Measurements 



Standard length, head length, snout length, 

 pectoral and pelvic fin lengths, eye diameter, and 



177 



