274 



Fishei^ Bulletin 100(2) 



inary results suggesting an increase in female natural 

 mortality rate (to 0.20) at the age of sexual maturity 

 (Campana"), longevity would be estimated at 29 years. 



Discussion 



Age and growth studies of lamnoids have often been con- 

 founded because of the continued debate over the peri- 

 odicity of band-pair formation. Parker and Stott ( 1965) first 



^ Campana, S. 2001. L'npubl. data. Marine Fish Division. 

 Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, 

 Nova Scotia, Canada B2Y 4A2 



suggested that two growth band pairs formed each year 

 (biannual band-pair deposition) in their study of the bask- 

 ing shark iCetorhuius maximiisy Pratt and Casey (1983) 

 assumed biannual band-pair deposition for shortfin mako 

 shark, Isiniis oxyriiichus. based on consistency with length- 

 frequency and tag-recapture analyses. Branstetter and 

 Musick ( 1994 ) also suggested biannual band-pair deposition 

 for the sand tiger shark, Carcharias taiiruti, based on mar- 

 ginal increment analysis (MIA) and examination of aquar- 

 ium-reared sharks. Cailliet et al. (198.3, 1985) assumed 

 annual band-pair deposition for Pacific coast shortfin mako 

 and white sharks, Carcharodon carcharias, based on mar- 

 ginal increment analysis. Wintner and Cliff (1999) stated 

 that they could not determine band periodicity using mar- 

 ginal increment analysis in the white shark off the coast 

 of South Africa, although one OTC-injected recapture sug- 

 gested annual deposition. With the exception of Winter and 

 Cliff (1999), direct validation of band periodicity, such as 

 by OTC injection or by known-age tag-recaptures, has not 

 previously been reported in lamnids. Although several stud- 

 ies have attempted validation with MLA (Branstetter and 

 Musick, 1994; Wintner and Cliff, 1999), this technique is not 



