36 
Fishery Bulletin 120(1) 
Carcharhinus acronotus, in the Gulf of Mexico versus the 
western North Atlantic Ocean; Driggers et al., 2004) and 
over ocean basins (e.g., porbeagle, Lamna nasus; Natanson 
et al., 2002; Francis et al., 2008). Different environmental 
conditions can affect growth and other biological processes 
of marine apex predators (Izzo and Gillanders, 2020). Blue 
sharks living under different oceanic conditions could 
have different growth and other life history characteris- 
tics (Megalofonou et al., 2009). Thus, it is not surprising 
that differences exist between oceans in the median size 
and age at maturity of blue sharks. 
The ability to compensate for fishing-induced changes 
in life history has important implications for the regula- 
tion and sustainability of populations (Johnston and Post, 
2009). There is evidence that density-dependent com- 
pensation and fisheries-induced selection pressure can 
influence a population’s ability to sustain or recover from 
fishing mortality (Walker, 1998; Cortés, 2007). In a fished 
population, one might expect an increase in growth rate 
or a decrease in size at maturity to compensate for higher 
mortality; however, only a few cases of density-dependent 
compensation have been empirically described for sharks, 
and for most species they are poorly understood (Cortés, 
1998, 1999, 2007; Walker, 1998). Growth rate has been 
reported to have increased in juvenile sandbar sharks 
(C. plumbeus) (Sminkey and Musick, 1995) and Atlantic 
sharpnose sharks (Rhizoprionodon terraenovae) (Carlson 
and Baremore, 2003), but no effects have been seen in 
dusky sharks (C. obscurus) (Natanson et al., 2014) follow- 
ing fisheries-induced decreases in abundance. The uncer- 
tainty of the North Atlantic blue shark stock leads to the 
possibility of the stock being overfished or of overfishing 
occurring (ICCAT”); therefore, changes in reproductive 
characteristics were examined. In this study, we did not 
observe a change in the reproductive characteristics of 
blue sharks in over 40 years of sampling. 
Conclusions 
We reexamined the reproductive characteristics of the 
blue shark in the Atlantic Ocean. Results of our analysis 
indicate that the median lengths and weights at maturity 
did not significantly change from those reported by Pratt 
(1979). We therefore combined all data from 1971 through 
2016 to obtain robust parameter estimates for manage- 
ment. Additionally, the calculated age at maturity also 
remained the same at 5 years for both sexes. 
Acknowledgments 
Thank you to all the participants and officials of shark 
tournaments over the years as well as cooperating 
commercial and recreational fishermen for allowing a 
member of the National Marine Fisheries Service Apex 
Predators Program to sample their blue sharks. We would 
like to thank everyone past and present in the Apex 
Predators Program, especially N. Kohler, R. McBride, 
C. McCandless, G. Skomal, and H. Pratt, Jr. We would also 
like to thank the reviewers, who improved the quality of 
this manuscript. 
Literature cited 
Aasen, O. 
1966. Blahaien, Prionace glauca (Linnaeus, 1758). Fisken 
Havet 1:1-15. 
Akaike, H. 
1973. Information theory as an extension of the maximum 
likelihood principle. In Proceedings of the 2nd interna- 
tional symposium on information theory (B. N. Petrov and 
F. Csaki, eds.), p. 267-281. Akademiai Kiado, Budapest, 
Hungary. 
Bigelow, H. B., and W. C. Schroeder. 
1948. Sharks. In Fishes of the western North Atlantic. Part 1: 
lancelets, cyclostomes, sharks (J. Tee-Van, C. M. Breder, 
S. F. Hildebrand, A. E. Parr, and W. C. Schroeder, eds.), 
p. 59-546. Mem. Sears Found. Mar. Res., Yale Univ. Press, 
New Haven, CT. 
Bonfil, R. 
1994. Overview of world elasmobranch fisheries. FAO Fish. 
Tech. Pap. 341, 119 p. FAO, Rome. 
Burnhan, K. P., and D. R. Anderson. 
2002. Model selection and multimodel inference: a practical 
information-theoretic approach, 2nd ed., 488 p. Springer, 
New York. 
Bustamante, C., and M. B. Bennett. 
2013. Insights into the reproductive biology and fisheries of 
two commercially exploited species, shortfin mako (/surus 
oxyrinchus) and blue shark (Prionace glauca), in the south- 
east Pacific Ocean. Fish. Res. 143:174-183. 
Canty, A., and B. Ripley. 
2017. boot: bootstrap R (S-Plus) functions. R package, vers. 
1.3-20. [Available from website, accessed July 2017.] 
Carlson, J. K., and I. E. Baremore. 
2003. Changes in biological parameters of Atlantic sharpnose 
shark Rhizoprionodon terraenovae in the Gulf of Mexico: 
evidence for density-dependent growth and maturity? Mar. 
Freshw. Res. 54:227-234. 
Carrera-Fernandez, M., F. Galvan-Magana, and B. P. Ceballos- 
Vazquez. 
2010. Reproductive biology of the blue shark Prionace glauca 
(Chondrichthyes: Carcharhinidae) off Baja California Sur, 
México. Aqua Int. J. Ichthyol. 16:101—-110. 
Castro, J. A., and J. Mejuto. 
1995. Reproductive parameters of blue shark, Prionace glauca, 
and other sharks in the Gulf of Guinea. Mar. Freshw. Res. 
46:967-973. 
Castro, J. I. 
2011. The sharks of North America, 640 p. Oxford Univ. 
Press, New York. 
Castro, J. I., C. M. Woodley, and R. L. Brudek. 
1999. A preliminary evaluation of the status of shark species. 
FAO Fish. Tech. Pap. 380, 72 p. FAO, Rome. 
Clark, E., and K. von Schmidt. 
1965. Sharks of the central Gulf coast of Florida. Bull. Mar. 
Sci. 15:13-83. 
Compagno, L. J. V. 
1984. FAO species catalogue. Vol. 4. Sharks of the world. An 
annotated and illustrated catalogue of shark species known 
to date. Part 2—Carcharhiniformes. FAO Fish. Synop. 125, 
p. 251-655. FAO, Rome. 
