174 
Fishery Bulletin 11 6(2) 
Table t 
Sex-specific parameters—the asymptotic length (L„) and the Brody growth coefficient (K) derived from the von Bertalanffy 
growth model (Eq. 1), the counterpart parameters, L„ inv and K inv , derived from the inverse von Bertalanffy growth model 
(Eq. 2), and minimum length (L min ) and daily ages (T min ) of cutlassfish (Trichiurus japonicus). Samples were collected at 2 
fishing ports, Kengfang and Tsukuan on the northeast and southwest coast of Taiwan, respectively, during 2013-2015. The 
95% confidence intervals are given in parentheses. 
Area 
Sex 
L„(mm) 
K(per year) 
L„ inv (mm) 
K inv (per year) 
(rnrn) ^min 
Kengfang (NE) 
Male 
370(304-436) 
0.32 (0.22-0.42) 
576(411-1275) 
0.17 (0.07-0.28) 
48 34 
Female 
520 (407-633) 
0.21 (0.15-0.27) 
1094(659-3068) 
0.08 (0.03-0.15) 
- 
Tsukuan (SW) 
Male 
264(238-290) 
0.56(0.42-0.70) 
399 (337-488) 
0.25 (0.18-0.34) 
75 51 
Female 
421(360-482) 
0.24 (0.18-0.30) 
600(477-878) 
0.14 (0.09-0.20) 
- 
state of fish on the basis of visual inspection of gonads: 
fish with visible male or female gonads were classified 
as mature fish, and those with eggs present in the 
gonads were females (otherwise males). Fish with no 
visible gonads were classified as immature and of un¬ 
known sex. In addition, we collected the pair of sagittal 
otoliths to estimate ages of fish. 
To ensure sufficient variation in lengths and ages 
for the subsequent growth analysis, for each area we 
compiled data on each group (i.e., immature fish, fe¬ 
males, and males) by randomly selecting 5-10 fish per 
20-ram size interval. Given the different ranges of pre- 
anal lengths of samples from Kengfang (range: 48-752 
mm) and Tsukuan (75-379 mm), we selected 305 and 
169 fish at the 2 areas, respectively. Further, because 
of a limited number of relatively small fish in the catch 
samples, we incorporated additional samples of small 
fish to conduct subsequent data analysis (no.=333 for 
Kengfang and no.=277 for Tsukuan). 
Otolith processing and aging 
There are generally no significant differences in otolith 
morphometries between the left and right otoliths for 
a large number of fish species (Hunt, 1992; Megalo- 
fonou, 2006). Consequently, we randomly selected one 
of each pair of sagittal otoliths per fish, cleaned the 
surface of the otolith with an ultrasonic cleaning ma¬ 
chine (Delta Sonicator DC150 4 , Delta Ultrasonic Co., 
Ltd., Taipei, Taiwan), and air-dried and mounted it in 
epoxy resin blocks. We then ground the otolith resin 
blocks to reveal the otolith cores, using silicon carbon 
paper (grades 2000 or 2500). 
We used the same aging techniques as those de¬ 
scribed in Shih et al. (2011): the otolith annuli were 
identified on the basis of the opaque bands. The first 
otolith annulus tended to be located at or beyond the 
4 Mention of trade names or commercial companies is for iden¬ 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
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c 
CD 
Z3 
or 
CD 
Kengfang, NE (n=574) 
80 
60 - 
40 
20 - 
200 400 600 
Pre-anal length (mm) 
800 
Tsukuan, SW (n=244) 
50 
30 _ 
io _ 
o 
Pre-anal length (mm) 
Figure 2 
Length distributions of cutlassfish Trichiurus japon¬ 
icus (males, females, and immature fish combined), 
sampled from the ports of (A) Kengfang and (B) 
Tsukuan, respectively, on the northeast (NE) and 
southwest (SW) coasts of Taiwan in 2013-2015. Ver¬ 
tical lines indicate mean lengths. 
