754 



Fishery Bulletin 98(4) 



2.10 

 2.00 

 1.90 

 1.80 

 1.70 

 1.60 

 1.50 

 1.40 

 1.30 

 I 20 

 I 10 

 1.00 

 090 



1 90 



1.80 



1-70 



1.60 



1 50 



1.40 



1.30 



1 20 f- 



I 10 



1.00 



090 

 



— 0- MOARl 

 -^i-M0AR2 

 -O M0AR3 

 -O-M0AR4 

 — •— M0AR5 

 -4— M0AR6 



A 

 -I 



(266) 



2 

 (238) 



3 

 (67) 



4 

 (13) 



5 

 (2) 



6 

 (2) 



-MOARl 

 M0AR2 

 M0AR3 

 M0AR4 



-M0AR5 

 M0AR6 

 M0AR7 



ir-- 



l 1 1 h 



(47) 



(257) 



3 

 (155) 



4 

 (48) 



5 

 (13) 



6 

 (2) 



7 

 (II 



Age group (year) 



Figure 5 



Tilt' relation.ship between mean otolith annular radius (MOAR) and age gi'oup for 

 TrichiuruN tepturus (top panel) and T. nonhaiensis (bottom panel). Vertical bai-s are 

 1 SE. numbers in parentheses are sample sizes. 



F2 720=4-39, P<0. 05; T. nanhcnensis: Fg .,.,1=23.78, P<0. 001.) 

 and species (ANCOVA: F.^ ,,,^.,= 169.69,'P<0.001). 



Discussion 



Our aging study of cutlassfishes from the South China Sea 

 was successful in that we 1 ) found distinct growth rings 

 on sectional sagittal otolith, 2) had excellent precision in 

 independent ring counts, and 3) used marginal increment 

 analyses to validate our aging method. In general, cutlass- 

 fishes from the northern seas of China (Misu, 1958, 1964; 

 Hamada, 1971; Sakamoto, 1976; Hong. 1980; Wu et al.. 

 1985a; Du et al., 1988; Hanabuchi, 1989; El-Haweet and 

 Ozawa, 1996) and the South China Sea (our study) deposit 



annuli in late winter or early spring, suggesting that ring 

 formation likely occurs in response to reduced water tem- 

 peratures and is not correlated with peak spawning as 

 indicated in Chen and Lee (1982). Summer is the peak 

 spawning period of 7^ Icpturus and T. nonhaiensis in the 

 South China Sea (Kwok and Ni, 1999). 



El-Haweet and Ozawa (1996) questioned whether Lee's 

 phenomenon existed in a trichiurid population from Japan, 

 having f()und no indication of Lee's or reverse Lee's phenom- 

 enon. We found that T. lepturus may exliibit reverse Lee's 

 phenomenon, which suggests that T. lepturus are not over- 

 fished in the South China Sea or that fishing mortality is 

 not size-selective, or that both situations may apply. Alterna- 

 tively, fast growing individuals in the T. lepturus population 

 may have greater chances of sun'ival and attain older ages. 



