Table 5.

Akaike’s information criterion (AIC) ranking of the models that explain the number of non-anguillid eel diadromous species in rivers of Japan (a), and coefficient values and associated probability of the best model (b).

(a)
Rank	Explanatory variable
	Depth	Distance from river mouth	Sediment	Vegetation	Velocity	Trans-river structure	AIC	∆AIC
1		−0.048			0.008	−0.019	323.5	0
2		−0.044	+		0.009	−0.019	324.1	0.542
3		−0.048		0.058	0.009	−0.018	325.3	1.716
4	−0.002	−0.048			0.008	−0.019	325.3	1.729
(b)
Parameter			Estimate	Standard error	z value		p value
(Intercept)			1.767	0.105	16.811		0.0000*
Trans-river structure			−0.019	0.005	−3.639		0.0003*
Distance from river mouth			−0.048	0.014	−3.315		0.0009*
Velocity			0.008	0.002	4.317		0.0000*

Plus and blank indicate significant or no significant effects of qualitative variable on the density of anguillid eels, respectively. ∆AIC indicates differences between AIC values of the best model (Rank 1) and selected model. The asterisks indicate statistical significant values.