Table 2. Parameter estimates from GLM models of fish ladder passage times in relation to ΔT.

			Parameter estimate
Dam	Run	n	Hour	Hour2	°C	ΔT
Ice Harbor	Spring Chinook	1,026	-0.192**	0.010**	0.053*	-0.080
	Summer Chinook	215	-0.067	0.004	0.119*	0.355**
	Fall Chinook	218	-0.170*	0.009**	0.061	0.557*
	Steelhead	1,352	-0.239**	0.010**	-0.001	0.309**
Lower Monumental	Spring Chinook	572	-0.280**	0.012**	0.008	-0.039
	Summer Chinook	184	-0.064	0.003	0.125**	0.308**
	Fall Chinook	115	-0.118	0.007	-0.044	0.166
	Steelhead	987	-0.159**	0.007**	0.035*	0.124*
Little Goose	Spring Chinook	880	-0.040	0.002	0.045*	-0.122
	Summer Chinook	174	-0.082	0.003	0.179**	0.310
	Fall Chinook	142	-0.098	0.006	0.218*	0.792
	Steelhead	1,048	-0.114**	0.005**	0.066**	0.442**
Lower Granite	Spring Chinook	635	-0.130**	0.007**	0.022	0.047
	Summer Chinook	174	-0.077	0.003	0.159**	0.207*
	Fall Chinook	122	-0.141	0.007*	-0.112*	0.797**
	Steelhead	911	-0.115**	0.007**	-0.001	0.286**

Passage times were calculated for radio-tagged Chinook salmon and steelhead at Snake River dams in 2000-2003. Independent variables included migration year (not uniquely estimable), hour of first detection at a base-of-ladder antenna (quadratic effect), water temperature (°C) at the ladder base at the time of first detection, and ΔT (the °C temperature difference between top-of-ladder and base-of-ladder sites). Positive ΔT parameter estimates indicate slower fish passage as ΔT increases.

^* P ≤ 0.05; ^** P ≤ 0.005