NOTE Smith et al.: Tnakis semifasaata recaptured after 20 years 



195 



others). The first translucent band was interpreted as the 

 first winter growth after parturition (year 0); the subse- 

 quent annulus interpreted as year 1. Band pairs distal to 

 the tetracycline mark were compared with the number of 

 years that the fish had been at liberty For publication, dig- 

 ital photomicrographs were further enhanced to improve 

 contrast and definition with Jasc Paintshop Pro software 

 (Jasc Software, Inc., 1999). 



Growth information for the other tagged fish (male, tag 

 no. 337, recaptured in South San Francisco Bay on 9 June 

 2001) was obtained by comparing tagging and recapture 

 size. Age and growth information for both recaptured 

 sharks was compared with Kusher et al.'s (1992) von Ber- 

 tanlanffy growth curves (their Figs. 4, 9, and 10) based on 

 aged vertebrae from 1) fishery and market samples, and 2) 

 earlier recaptures from the same 1979 tagging experiment. 



Results 



The shark recaptured in July 1999 was a mature female 

 measuring 124 cm TL at recapture. At liberty growth and 

 exact time at liberty could not be calculated because the 

 tag number had worn away, preventing referral back to 

 original tagging length and day. Because the one-time tag- 

 ging experiment took place 26 July-13 September 1979, 

 the fish had been at liberty from 19.8 to 19.9 years. The 

 tetracycline mark was visible as a thin yellow line in all 

 vertebral sections examined (Fig. 1). In less than a minute, 

 the fluorescence began to decay rapidly, much more rapidly 

 than tetracycline marks observed by the senior author in 

 previous recaptured sharks (sharks at liberty 7 years or 



less). This fast decay made viewing of actual samples brief; 

 most time was dedicated to setting up and taking digital 

 photomicrographs of the sections. 



Twenty annuli up to winter 1998 (including the 1979-80 

 winter annulus deposited after tagging) were visible distal to 

 the time mark (Fig. 2), including a partially formed opaque 

 band interpreted as the 1998 summer band (Fig. 3). We 

 could not determine with any certainty whether the narrow 

 opaque edge represented the beginning of the summer 1999 

 band (Fig. 3). On all sections examined, the last band pair at 

 the centrum edge (i.e. the most recently deposited) was very 

 naiTow and faint, or incomplete and difficult to differentiate, 

 especially on vertebral sections that were sliced too thick or 

 too thin (best thickness was 0.6 mm). Proximal to the OTC 

 mark were five annuli, indicating that the fish was 4+ yr old 

 at tagging and was probably born in spring of 1974. The fish 

 was aged as 24-i- or in its 25'*^ year. Width of the opaque bands 

 indicative of annual summer growth was highly variable, al- 

 though it generally tended to decrease with increasing age. 

 Greatest relative growth in centrum diameter occuiTed in the 

 first few years of life, and also in 1985, 1986, and 1987, judg- 

 ing from the width of the con'esponding opaque zones (ages 

 11, 12, and 13). The recapture size (124 cm TL) was 11 cm 

 smaller than that predicted for an age-25 female with the 

 von Bertalanffy growth function ( VBGF) generated by Kush- 

 er et al. ( 1992, their Fig. 4) for 162 untagged leopard sharks. 

 But it was close to that predicted by their FISHPARM X'BGF 

 generated from band counts and lengths of tag recaptures 

 from this same 1979 experiment (Kusher et al. 1992, their 

 Fig 10). 



The other recaptured leopard shark (a male, no. 337) 

 was caught 9 June 2001 in South San Francisco Bay off 



