FISHERY BULLETIN: VOL. 84, NO. 3 



encouraging, use of otoliths to resolve age and 

 growth discrepancies for Atlantic sailfish has not 

 been reported, and no conclusive evidence is avail- 

 able to validate the accuracy of age estimates for 

 this species using any method. We present an 

 analysis of dorsal spines and otoliths obtained from 

 one tag-recaptured Atlantic sailfish, where age was 

 very closely approximated from tagging records, to 

 help resolve the problems associated with ageing 

 this species. 



METHODS 



The Cooperative Gamefish Tagging Program of 

 the Southeast Fisheries Center Miami Laboratory 

 recovered a tag from a female Atlantic sailfish, 

 which had been recaptured on 14 January 1984, off 

 Boynton Beach, FL (Prince and Lee 1984). This fish 

 was originally tagged and released off the Florida 

 Keys (Islamorada) on 5 March 1973, at an estimated 

 weight of 18.2 kg (about 40 lb). When recaptured 

 it weighed 24.6 kg (54 lb) and had a lower jaw fork 

 length (LJFL) of 176.5 cm. The sailfish appeared 

 to have a healthy external appearance when caught 

 and body proportions and overall morphology were 

 within the normal range for a specimen of this size. 

 The entire fish was made available to us by J. T. 

 Reese Taxidermist, Inc. (Ft. Lauderdale, FL), and 

 both sagittae and the first six dorsal spines were 

 sampled for age determination. 



Dorsal Spine Analysis 



Dorsal spines were collected from the tagged 

 Atlantic sailfish following the procedures of Prince 

 and Lee (1982). Past efforts to age sailfish using dor- 

 sal spines have relied on spine number 4 as the 

 source of age and growth information (Jolley 1974, 

 1977; Hedgepeth and Jolley 1983). We collected the 

 first six anterior dorsal spines to insure that the 

 number assigned to each spine was accurate for 

 identification and analysis and to gain information 

 about possible differences between spines. The first 

 two anterior dorsal spines of sailfish are greatly 

 reduced in size compared with spines 3-6 and were 

 not used to estimate age. In addition, spines pos- 

 terior to spine number 6 have a smaller diameter 

 and were not used for age determination. This deci- 

 sion was based, in part, on a report by Robins 4 and 

 Robins and de Sylva (1963) who believed that the 



4 Robins, C. R., Professor, Rosenstiel School of Marine and At- 

 mospheric Sciences, University of Miami, 4600 Rickenbacker 

 Causeway, Miami, FL 33149, pers. commun. 1982. 



posterior dorsal spines of billfish do not grow 

 throughout their entire lifetime and recommended 

 that only anterior spines be used for age and growth 

 studies. 



Dorsal spines 3-6 were cleansed of tissue, labeled 

 with a collection number, and preserved in isopropyl 

 alcohol (98%). The methods of sectioning dorsal 

 spines given by Hedgepeth and Jolley (1983) and 

 Prince et al. (1984) were used in this study. Dorsal 

 spine number 4 was sectioned by M. Y. Hedgepeth 

 at the laboratory of the Florida Department of 

 Natural Resources (FDNR), West Palm Beach, FL, 

 to ensure that processing of this spine was identical 

 with methods previously reported. We sectioned 

 spines 3, 5, and 6 using a Buehler ISOMET 5 saw 

 and a 10.16 cm diameter diamond wafer blade. At 

 least 2 or 3 sections (0.44-0.46 mm thick) were taken 

 from each spine. Additional sections were taken 

 from spine number 4 after it had been processed by 

 FDNR personnel. All spine sections were placed into 

 labeled vials with isopropyl alcohol (98%) for storage 

 and extraction of oil. A single section was selected 

 and allowed to air dry before microscopic examina- 

 tion. 



Dorsal spine sections were examined initially 

 using a compound stereoscope (6.0 x) with trans- 

 mitted light in order to assess that portion of the 

 section not affected by the vascularized core. Mea- 

 surements (in millimeters, mm) of the solid bone 

 area in the distal portion of the right lobe of each 

 section were taken along a straight-line counting 

 path from the focus to the outside margin of the 

 structure. 



We assigned an age to each spine by counting only 

 concentric translucent bands that were continuous 

 around the circumference of the entire section. In 

 transmitted light, the zonations consisted of a dark 

 opaque zone followed by a light translucent zone. 

 D. W. Lee made three repeated counts of translu- 

 cent zones using a compound stereoscope at 12.0 to 

 25.0 x magnification. 



Otolith Analysis 



The general methods of Radtke and Dean (1981) 

 and Wilson and Dean (1983) were used to extract 

 and prepare the sagittae for examination by scan- 

 ning electron microscopy (SEM) and light micro- 

 scopy. The sagittae were removed from the tagged 

 Atlantic sailfish, cleaned with sodium hypochloride 

 solution, and rinsed in xylene and then 95% ethanol. 



5 Reference to trade names and products does not imply endorse- 

 ment by the National Marine Fisheries Service. 



494 



