Table 1 The effect size of predatory lake trout on aquatic and terrestrial ecosystems.

The response variables for the past (before lake trout population growth) and present (after) were compared using a log response ratio of means [log10(Xpresent/Xpast)]. Lake trout enhanced the variable when the ratio was positive and reduced the variable when the ratio was negative; ratios near zero indicate that the variable was similar between the two time periods. CI, confidence interval.

VariablePast*PresentLog ratio
Year(s)Mean95% CIYear(s)Mean95% CI
Fish population responses
Lake trout abundance (total number × 1000)1998–200295.32.82013–2017843.96.00.95
Cutthroat trout abundance (CPUE)1980–198444.64.22013–201722.11.2−0.31
Longnose sucker abundance (CPUE)1980–198430.01.52013–20174.60.4−0.82
Cutthroat trout spawners (mean number observed)1989–199352.87.12013–20175.30.5−1.00
Aquatic ecosystem effects
Small zooplankton biomass (mg/liter)1977–198067.827.3201730.317.0−0.35
Large zooplankton biomass (mg/liter)1977–19808.55.02017102.924.01.08
Chlorophyll a concentration (μg/liter)19722.20.320170.50.2−0.64
Large zooplankton [H. shoshone length (mm)]1977–19802.40.220174.40.20.26
Large zooplankton [D. pulicaria length (mm)]1977–19801.90.120172.70.00.16
Small zooplankton [L. ashlandi length (mm)]1977–19800.70.020170.90.10.12
Secchi disk depth (m)†19769.90.1200511.40.10.06
Terrestrial ecosystem effects
Bear occurrence on spawning streams (proportion of visits)1989–19930.50.02013–20170.20.0−0.30
River otter use of cutthroat trout (prevalence in scat)2002–20030.730.062006–20080.530.14−0.14
Osprey nest count (total number)1987–199137.62.22013–20173.20.1−1.07
Osprey nest success (proportion that fledged)1987–199158.83.42013–201731.47.1−0.27
Bald eagle nest count (total number)1985–19896.40.32013-20177.60.70.07
Bald eagle nest success (proportion that fledged)1985–198956.06.12013–201770.43.60.10

*All data were collected before significant lake trout population growth with the exception of river otters, which were collected later during a period of lake trout population growth and cutthroat trout decline (24).

†Secchi depth was calculated using the model in fig. S6 based on 15 August (Julian day 227) 1976 and 2005.