Related Experiment Video
Updated: Jul 1, 2026
16:03
A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms
Published on: January 11, 2015
Predator harvesting in stage dependent predation models: insights from a threshold management policy
Michel Iskin da Silveira Costa1
1Laboratório Nacional de Computação Científica, Av. Getúlio Vargas 333, Quitandinha, Petrópolis-RJ 25651-070, Brazil. michel@lncc.br
Mathematical Biosciences
|September 13, 2008
Summary
Raising predator mortality can paradoxically increase predator populations, known as the hydra effect. A threshold management policy can prevent this ecological collapse and predator extinction.
Area of Science:
- Ecology
- Population Dynamics
- Conservation Biology
Background:
- Stage-dependent predation can lead to the hydra effect, where increased predator mortality paradoxically increases predator density at equilibrium.
- Current management strategies, adjusting harvest rates based on past population responses, risk catastrophic collapse of predator species.
Purpose of the Study:
- To introduce and evaluate a threshold management policy as a strategy to avoid the hydra effect.
- To explore the potential applications of threshold policies in other ecological contexts.
Main Methods:
- The study theoretically investigates the dynamics of stage-dependent predation and its implications for population management.
- It proposes a threshold management policy and contrasts its outcomes with conventional approaches.
Main Results:
- Conventional management strategies adjusting harvest rates can inadvertently trigger the hydra effect, leading to population collapse.
- The proposed threshold management policy effectively prevents the hydra effect, safeguarding predator populations from extinction.
Conclusions:
- Threshold management policies offer a robust alternative to conventional methods for preventing the hydra effect and ensuring predator species survival.
- Threshold policies show promise for application in areas including intermediate disturbance, density-trait mediated interactions, and anti-predatory behavior.
Related Concept Videos
02:39Predator-Prey Interactions
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.Although predation is commonly associated with carnivory, for...
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
01:28Microbial Interactions: Predation
Microbial predation refers to the process by which one microorganism kills and consumes another to obtain nutrients and energy. It encompasses both bacterial and protozoan predators. This interaction plays a crucial role in shaping microbial communities and regulating nutrient cycling.Bacterial Predators: Epibiotic vs. EndobioticBacterial predators are classified based on their mode of attack as either epibiotic or endobiotic. Epibiotic predators, such as Vampirococcus, attach to the surface of...
01:38Limits to Natural Selection
Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...
01:50Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...