80 
Fishery Bulletin 11 7(1-2) 
Table 
Fitted parameters from 2 segmented regression models (SRMs) for estimating the growth of the captive male whale shark 
(Rhincodon typus ) at the Okinawa Churaumi Aquarium in Okinawa, Japan. The SRMs used 1 or 2 break points (BKs) ex¬ 
pected to be turning points between the 3 growth stages: immature, maturing, and mature. The average monthly changes 
in growth of body length, during the immature stage (aO, during the mature stage in the model with 1 BK or the maturing 
stage in the model with 2 BKs (ot 2 ), and during the mature stage in the model with 2 BKs (a 3 ), are given with standard 
errors of the means (SEs). The turning points from the immature to mature stage in the 1-BK model (BKi), from the im¬ 
mature to maturing stage in the 2-BK model (BKi), and from the maturing to mature stage in the 2-BK model (BK 2 ) are 
given with 95% confidence intervals (Cl). r 2 =coefficient of determination. 
Slopes 
cq (SE) a 2 (SE) a 3 (SE) BK 1 (95%CI) BK 2 (95% Cl) Intercept (SE) r 2 
Model with 1BK 2.243(0.072) 0.467(0.320) - 170.5(154.5-186.4) - 449.9(8.2) 0.994 
Model with 2 BKs 2.281(0.086) 1.375(0.428) 0.050(0.729) 149.7 (117.8-181.7) 195.6(162.8-228.3) 447.8(8.6) 0.993 
o 
° I_|_J_ T _]_1_J_1_1_ ' I |_I_1_I_J_I_L 
0 50 100 150 200 
Captive period (month) 
Captive period (month) 
Figure 1 
Change in monthly body length of a male whale shark ( Rhin¬ 
codon typus) in captivity at the Okinawa Churaumi Aquarium 
in Okinawa, Japan, given in centimeters in total length and rep¬ 
resented by segmented regression models (SRMs) with (A) 1 and 
(B) 2 break points. The dotted lines indicate the 95% confiden¬ 
tial intervals. The data used in the SRMs were collected from 
March 1995 through December 2013. 
gating (claspers extending behind the posterior 
margin of pelvic fins), and completed (claspers 
no longer extending). Statistical analyses were 
conducted by using the nonparametric Krus- 
kal-Wallis test followed by the nonparametric 
Steel-Dwass post-hoc test. The relationship 
between hormone levels and water tempera¬ 
ture also was tested by using a regression 
analysis. Measurements are reported as means 
with standard errors (SEs), unless otherwise 
noted. 
Results 
Growth 
According to the SRM that used 1 BK, the av¬ 
erage growth rate for body length (slope) from 
March 1995 through May 2009 was 2.24 cm/ 
month (SE 0.07) (Fig. 1A, Table). During this 
period, the TL increased from 460 to 832 cm. 
The average growth rate between May 2009 
and December 2013 decreased to 0.47 cm/ 
month (SE 0.32), 9 with TL changing from 832 
to 854 cm. Based on the estimates from the 
SRM that used 2 BKs (Fig. IB), the average 
monthly growth from March 1995 through 
August 2007 was 2.28 cm (SE 0.07), with TL 
increasing from 460 to 789 cm (Table). From 
August 2007 through June 2011, the growth 
rate was 1.38 cm/month (SE 0.43) with TL 
changing from 789 to 852 cm. The growth rate 
from June 2011 through December 2013 was 
0.05 cm/month (SE 0.73) with TL increasing 
from 852 to 854 cm. Both SRMs revealed that 
the individual grew in length rapidly until it 
reached approximately 800 cm TL. Consider¬ 
ing annual growth in TL, the whale shark grew 
from 460 cm to >800 cm at a rate of 26.9 cm/ 
