Goldman and Musick, Growth and maturity of Lamna ditropis 



289 



rings per year. However, validation of sin- 

 gle annual ring (band pair) deposition has 

 now been demonstrated from recaptures of 

 oxytetracycline(OTC)-injected mako sharks 

 (Natanson et al., in press), as well as with 

 a new technique where bomb radiocarbon is 

 used to validate ages in long-lived sharks 

 (Campana et al., 2002; Ardizzone et al., 

 in press). 



Lamnid sharks are endothermic (Carey 

 et al., 1985; Lowe and Goldman, 2001), and 

 prior to the Campana et al. (2002) and Ar- 

 dizzone (in press) radiocarbon studies, it 

 appeared that lamnid sharks might possess 

 fairly high growth rates (growth coefficient, 

 k) compared to other sharks, particularly 

 those that grow to a large size (Musick, 

 1999). However, with mako sharks now ap- 

 pearing to have a growth coefficient around 

 0.072/yr (sexes combined)(Cailliet et al. 

 1983), the validation of porbeagle shark 

 (Lamna nasiis) age and growth (/^ = 0.06 and 

 0.08/yr for females and males, respective- 

 ly) (Natanson et al. 2002), and estimates 

 of white shark (Carcharodon carcharias) 

 growth coefficients ranging from 0.058 to 

 0.071/yr (for sexes combined)(Cailliet et 

 al., 1985; Wintner and Cliff, 1999; Malcolm 

 et al. 2001), salmon sharks appear to be 

 the species that possess the higher growth 

 rates (Tanaka, 1980; present study). Salm- 

 on sharks are not only endothermic, but 

 also appear to be homeothermic (i.e., defend 

 a specific body core temperature regardless 

 of ambient temperature) (Goldman et al., 

 2004). This uncommon physiological trait 

 for a shark, combined with a diet that in- 

 cludes many lipid-rich species (e.g., salmo- 

 nids), may influence the growth rate of this 

 species, but endothermy does not appear to 

 be correlated with faster growth rates in lamnid sharks 

 (Goldman, 2002). 



The most recent demographic analysis has indicat- 

 ed that salmon shark populations in the eastern and 

 western North Pacific are stable at this time (Gold- 

 man, 2002) and current research is beginning to as- 

 sess standing stock and population numbers, as well 

 as examine the stock structure of salmon sharks in the 

 eastern and western North Pacific in order to further 

 responsible management of the species. The differences 

 in growth rates and strong sexual segregation across 

 the North Pacific basin and an unknown rate of current 

 bycatch complicate management of this species. 



Acknowledgments 



We are grateful to the many people have helped in field 

 and lab operations. We thank J. Castro, J. Herschleb 

 and K. Herschleb of the FV Pagan, K. Anderson, B. 



Precaudal length (cm) 



Figure 7 



Comparison of weight-length relationships of eastern and western 

 North Pacific salmon sharks <~Lamna diiropis) (A) females, and (B) 

 males. Western North Pacific data were obtained from Tanaka (1980) 

 and Nagasawa (1998). 



Block, and L. Hulbert for assistance in the field. We 

 thank R. Candopoulos, the crew, and many passengers 

 aboard the FV Legend and B. Steffen (FV Sea Sound) 

 for vertebral samples collected on sport fishing trips, 

 and to the following Alaska Department of Fish and 

 Game biologists for their logistic support, field help and 

 overall assistance with our Alaska shark research: B. 

 Bechtol, S. Meyer, C. Stock, M. Miller, D. Vincent-Lang, 

 and D. Branshaw and D. Anderson of the RV Montague. 

 We thank S. Anderson for his assistance with sample 

 collection and unwavering endurance in the field, and J. 

 Gelsleichter for the histological workup of the oviducal 

 glands. We also thank J. DiCosimo (North Pacific Fish- 

 ery Management Council) for her logistical support and 

 assistance in the field. This research was supported in 

 part by the National Geographic Society's Committee for 

 Research and Exploration (grant no. 6714-00), Sigma-Xi, 

 and the Lerner-Gray Fund for Marine Research. This 

 research represents a portion of K.J. Goldman's Ph.D. 

 dissertation conducted at the College of William and 



