Viducic et al.: Reproductive characteristics for Prionace glauca in the North Atlantic Ocean 
Proportion mature 
200 
(cm) 
100 
Fork 
® 
_ 
=} 
2 
oO 
E 
Cc 
S 
= 
(o) 
Q 
[e) 
_ 
a 
50 100 150 
Weight (kg) 
Proportion mature 
200 
33 
592 192.5 cm FL # 
i 
100 150 250 
Weight (kg) 
200 
Figure 2 
Maturity ogives by sex for blue sharks (Prionace glauca) caught in the western North Atlan- 
tic Ocean between New Jersey and the Flemish Cap during 1971-2016: fork length (FL in 
centimeters) for (A) females and (B) males and weight (in kilograms) for (C) females and (D) 
males. Open circles and black triangles indicate individuals in the mature and juvenile stages, 
respectively. In each panel, a horizontal line indicates and a value is provided for the median 
length or weight at 50% maturity (L;) or W;)). The dotted and dashed lines indicate 95% con- 
fidence intervals. 
likely the result of sampling bias rather than a biologi- 
cally significant difference. We therefore combined the 
data for all time periods to provide an updated size at 
median maturity for males of 192.5 cm FL and 49.5 kg 
and feel this estimate of current reproductive parameters 
for the population is robust (Fig. 2). 
Revisiting Pratt (1979) 
For male blue sharks, we used Pratt’s (1979) original stag- 
ing and found that his estimate of average size at matu- 
rity of 183.0 cm FL is lower than our calculated estimate 
of median maturity (184.1 cm FL) for TP1. We analyzed 
the female data from Pratt (1979), producing an L;, of 
190.6 cm FL, which is slightly higher than Pratt’s esti- 
mated size at first maturity of 185.0 cm FL. Pratt (1979) 
did not calculate median size at maturity for females; 
therefore, L;) values calculated from his data for TP1 were 
used for comparison. 
Median age at maturity 
When the median L;, for each sex was combined with 
the published growth curves from Skomal and Natanson 
(2003), age at median maturity stayed stable at 5 years for 
both sexes. 
Discussion 
Changes in life history characteristics in response to envi- 
ronmental conditions or fishing pressure over time are a 
concern, particularly with climate change. Additionally, 
having up-to-date sex-specific inputs is important for 
management. Results from the statistical comparisons 
between current and past reproductive characteristics in 
this study indicate a difference in the parameter estimates 
for male blue sharks while estimates for females have 
remained unchanged since the 1970s. For females, Ls 
