Effects of metamorphosis timing and the larval growth rate on the latitudinal distribution of sympatric freshwater eels, Anguilla japonica and A. marmorata, in the western North Pacific

Zoological Studies

Table 3 Mean increment widths of radii of R _m , R _t , and R _t−m in otoliths of Anguilla japonica and A. marmorata glass eels

Species	Sampling site	Sampling date	Increment width in μm (n)
Species	Sampling site	Sampling date	R _m	R _t	R _t−m
A. japonica ^a	Tungkang River, Taiwan	30 December 92	0.8 ± 0.07 (5)	0.9 ± 0.09 (5)	1.2 ± 0.31 (5)
	Tungkang River, Taiwan	24 March 93	0.8 ± 0.07 (7)	0.8 ± 0.03 (5)	1.4 ± 0.19 (5)
	Shuangshi River, Taiwan	20 December 92	0.8 ± 0.07 (7)	0.9 ± 0.03 (6)	1.5 ± 0.48 (6)
	Shuangshi River, Taiwan	17 February 93	0.9 ± 0.09 (3)	1.0 ± 0.04 (2)	1.4 ± 0.03 (2)
	Mingchiang River, China	1 March 93	0.7 ± 0.02 (5)	0.9 ± 0.06 (5)	1.4 ± 0.38 (5)
	Chyantarng River, China	17 February 93	0.7 ± 0.08 (7)	0.8 ± 0.03 (4)	1.3 ± 0.17 (4)
	Yalu River, China	3 May 93	0.8 ± 0.09 (8)	0.9 ± 0.05 (8)	1.3 ± 0.45 (8)
	Ichinomiya River, Japan	10 January 94	0.7 ± 0.06 (5)	0.8 ± 0.05 (5)	1.2 ± 0.26 (5)
Overall (μ₁₎			0.78 ± 0.07 (47)	0.88 ± 0.05 (40)	1.34 ± 0.28 (40)
A. marmorata	Cagayan River, the Philippines	19 May 08	1.0 ± 0.18 (13)	1.1 ± 0.14 (13)	1.84 ± 0.46 (13)
	Hsiukuluan River, Taiwan	20 May 08	0.9 ± 0.10 (13)	1.2 ± 0.18 (13)	2.29 ± 0.72 (13)
	Kurio River, Japan	6 June 96	0.9 ± 0.14 (15)	1.1 ± 0.17 (15)	2.18 ± 0.61 (15)
Overall (μ₂₎			0.93 ± 0.14 (41)	1.13 ± 0.16 (41)	2.10 ± 0.60 (41)
Difference (μ₂₋μ₁₎			0.15	0.25	0.76
Significance			A. marmorata > A. japonica	A. marmorata > A. japonica	A. marmorata > A. japonica

^aCheng and Tzeng (1996). Mean increment widths (±SD) of radii of R _m, R _t, and R _t−m in otoliths of A. japonica and A. marmorata glass eels. n, number of individuals used for increment width measurements.