FISHERY BULLETIN: VOL. 85, NO. 2 



of 21 specimens taken on longlines fished in con- 

 tinental shelf waters of the northwestern Gulf in 

 summer and along the shelf edge in winter from 

 1981 to 1985. Nine more tiger sharks were examined 

 during a summer tournament in Texas. Between 

 1978 and 1985, an additional 41 specimens were 

 tagged and released between Panama City, FL and 

 Brownsville, TX. Data on morphometries, lengths 

 at maturity, and weight/length relationships were 

 supplemented by specimens collected in the north 

 central Gulf of Mexico (Branstetter 1981) and by 23 

 weight/length records from specimens taken from 

 1976-81 Galveston, TX shark tournaments. 



Measurements were taken as the straight line 

 distance between perpendiculars with caudal fins 

 placed in a natural position (Dodrill 1977; 

 Branstetter 1981, 1986). The upper caudal lobe 

 angle was calculated to be approximately 21-22°, 

 based on a formula by Dodrill (1977) which places 

 the vertex of the angle at the upper caudal notch. 

 This is slightly less than the values calculated by 

 Thompson and Simanek (1977), who measured the 

 angle through the center of the caudal peduncle, not 

 the upper caudal notch. Total lengths (TL) are used 

 throughout this report, but because measurements 

 were taken by different people, there could have 

 been variation in placement of the long flexible 

 upper caudal lobe into a natural angle. Therefore, 

 for each regional sample, regressions were 

 calculated to compare total length to the more 

 precisely measureable fork length (FL) or precaudal 

 length (PCL). 



Weights of tiger sharks from tournaments and 

 Virginia specimens were made with balance beam 

 scales, and Gulf of Mexico specimens taken on long- 

 lines were weighed with spring scales. Scales were 

 tested for accuracy between sampling periods. 



Reproductive development and maturity deter- 

 minations follow Springer (1960), Clark and von 

 Schmidt (1965), and Branstetter (1981). Males were 

 considered mature only if the claspers were fully 

 calcified and siphon sacs were fully developed. 

 Sperm is produced before the claspers calcify and 

 cannot be used as a criterion of maturity. Virginity 

 in females, indicated by the presence or absence of 

 a hymen covering the distal end of the oviducts, is 

 not a criterion for maturity. Females were con- 

 sidered mature when developing or ripe eggs were 

 in the ovary, eggs or embryos were present in 

 the uteri, or by uterine expansion of nongravid 

 females. 



For age and growth analysis vertebrae were 

 removed from 25 females (125-381 cm) and 19 males 

 (156-381 cm) from off Virginia, and from 10 females 



(91-355 cm) and 7 males (140-340 cm) from the Gulf 

 of Mexico. An additional eight Gulf of Mexico spe- 

 cimens (100-285 cm) had been processed for sale, 

 and sex could not be determined. A section of the 

 vertebral column was removed from under the 

 origin of the first dorsal fin or, when sampling com- 

 mercial operatit s, from the cervical region dorsal 

 to the branchial chamber. Samples were frozen or 

 preserved in 10% formalin and stored in ethyl or 

 isopropal alcohol. Following methods detailed in 

 Branstetter and McEachran (1986), individual cen- 

 tra were cleaned and a sagittal section cut from the 

 center. Sections were polished on wet 400 grit sand- 

 paper and observed with a binocular dissecting 

 microscope using transmitted light. To block inci- 

 dental light, an opaque tube was placed over the 

 section between the microscope stage and objec- 

 tive. 



Distinct marks (annuli), as illustrated in Casey et 

 al. (1985: fig. 1) and Branstetter and Stiles (in press: 

 fig. 1), were visible in the intermedialia of cen- 

 trum sections. These annuli corresponded to trans- 

 lucent areas in the corpus calcareum and to the 

 outer edge of translucent bands on the centrum face. 

 The annuli formed distinct borders for the growth 

 bands. Bands were counted without knowledge of 

 the length of the specimen. All band counts were 

 made by the senior author. Counts for each 

 specimen were performed twice, and if agreement 

 was not reached, a third count was made for 

 comparative purposes. The distance from the 

 section focus to each annulus, centrum dorsal radius, 

 and marginal increment was measured on a line 

 from the focus through the center of the inter- 

 medialia. 



The periodicity of annulus formation was verified 

 through marginal increment analysis and corrob- 

 orated with comparisons to back-calculated lengths 

 at each mark. Relative marginal increments were 

 calculated by dividing absolute marginal increment 

 widths by the width of the last fully formed band, 

 and relative marginal increments were compared 

 by month of capture. Back calculations were per- 

 formed using the Dahl-Lea method (Carlander 1969) 

 where 



TL, = Mi(TL)CR 



and TL, = total length at mark i (M,), TL = ob- 

 served length at capture, and CR = centrum radius. 

 Back calculations were analyzed for each sample as 

 a whole and by age class. 



Tiger sharks are born in the Gulf of Mexico and 

 along the southeastern U.S. Atlantic coast in early 



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