Related Experiment Video
Updated: Jan 15, 2026
06:48
Assessing Intertidal Populations of the Invasive European Green Crab
Published on: September 16, 2020
6.5K
Non-native prey availability and over-compensatory density dependence drive population dynamics of a native fish
Madaline M Cochrane1, Timothy J Cline1, Travis S Schmidt2
1Department of Ecology, Montana State University, Bozeman, Montana, USA.
Summary
Prey availability, particularly non-native kokanee, significantly boosts bull trout survival and abundance. Understanding these dynamics is key for managing this threatened cold-water species and its fisheries.
Area of Science:
- Ecology
- Fisheries Science
- Conservation Biology
Background:
- Bull trout (Salvelinus confluentus) are a threatened cold-water species facing decline from habitat loss, overfishing, invasive species, and climate change.
- Prey availability's role in bull trout population dynamics under multiple stressors is poorly understood, hindering conservation efforts.
Purpose of the Study:
- To quantify the effects of non-native prey (kokanee), angling, climate, and density dependence on bull trout population dynamics.
- To inform conservation and management strategies for threatened bull trout populations.
Main Methods:
- Utilized a stage-based integrated population model.
- Analyzed 40 years (1980-2023) of data from Lake Koocanusa, a transboundary reservoir and river system.
- Quantified impacts of kokanee biomass, angling pressure, climatic variation, and density-dependent processes.
Main Results:
- Bull trout populations are regulated by density-dependent processes, including over-compensation in recruitment and reduced adult survival.
- Increased kokanee biomass and restricted harvest significantly improved bull trout survival and abundance.
- Reduced water availability had a limited negative impact on sub-adult production.
Conclusions:
- Prey availability, including non-native species, is critical for supporting bull trout populations.
- Sustainable fisheries can be achieved, especially with high kokanee biomass, potentially sustaining a harvest of 300 individuals annually.
- Effective management requires addressing the interplay between environmental threats, prey dynamics, and density dependence across all bull trout life stages.
Related Concept Videos
00:57Population Growth
27.8K
Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.
27.8K
02:39Predator-Prey Interactions
21.0K
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.
21.0K
01:21Frequency-dependent Selection
23.0K
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
23.0K
00:30What are Populations and Communities?
37.1K
Overview
37.1K
02:34Competition
24.3K
When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction. Even if two competing individuals or populations do not interact directly, the overall fitness of both competitors is lowered as a result of not having full access to the limited resource.
24.3K
02:04Conservation of Small Populations
16.6K
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less...
16.6K