Harvesting, census timing and "hidden" hydra effects

Frank Hilker, Eduardo Liz

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Population control in some form of harvesting might be expected to reduce population size, but quite the opposite can happen due to the hydra effect. This phenomenon describes an increase in population size with increased mortality. One mechanism causing hydra effects is the temporal separation of (i) harvesting and (ii) density-dependent reproduction. Here we consider discrete-time models of these two processes. It is commonly believed that harvesting needs to precede reproduction for a hydra effect to occur. We show that, by contrast, hydra effects also take place for harvest after reproduction. Due to the timing of population census, however, the hydra effect will not be measured and thus remains ‘hidden’. As a consequence, managers may miss out on the opportunity to increase both the yield and the remaining stock of renewable resources. If harvesting aims at controlling pest species, management interventions may backfire in the sense that the pest increases rather than decreases—and, to make things even worse, this may actually go unnoticed. To remedy these undesirable consequences, we propose a modelling framework that can reveal hidden hydra effects. Our results are based on rigorous mathematical proofs that the order of two events does not matter for standard harvesting/hunting strategies.
Original languageEnglish
Pages (from-to)95-107
Number of pages13
JournalEcological Complexity
Volume14
DOIs
Publication statusPublished - Jun 2013

Fingerprint

Hydra
census
population size
pests
pest species
renewable resources
renewable resource
hunting
effect
managers
mortality
modeling

Cite this

Harvesting, census timing and "hidden" hydra effects. / Hilker, Frank; Liz, Eduardo.

In: Ecological Complexity, Vol. 14, 06.2013, p. 95-107.

Research output: Contribution to journalArticle

Hilker, Frank ; Liz, Eduardo. / Harvesting, census timing and "hidden" hydra effects. In: Ecological Complexity. 2013 ; Vol. 14. pp. 95-107.
@article{9efa3535fbd1442a8a3922b4c2e3d771,
title = "Harvesting, census timing and {"}hidden{"} hydra effects",
abstract = "Population control in some form of harvesting might be expected to reduce population size, but quite the opposite can happen due to the hydra effect. This phenomenon describes an increase in population size with increased mortality. One mechanism causing hydra effects is the temporal separation of (i) harvesting and (ii) density-dependent reproduction. Here we consider discrete-time models of these two processes. It is commonly believed that harvesting needs to precede reproduction for a hydra effect to occur. We show that, by contrast, hydra effects also take place for harvest after reproduction. Due to the timing of population census, however, the hydra effect will not be measured and thus remains ‘hidden’. As a consequence, managers may miss out on the opportunity to increase both the yield and the remaining stock of renewable resources. If harvesting aims at controlling pest species, management interventions may backfire in the sense that the pest increases rather than decreases—and, to make things even worse, this may actually go unnoticed. To remedy these undesirable consequences, we propose a modelling framework that can reveal hidden hydra effects. Our results are based on rigorous mathematical proofs that the order of two events does not matter for standard harvesting/hunting strategies.",
author = "Frank Hilker and Eduardo Liz",
year = "2013",
month = "6",
doi = "10.1016/j.ecocom.2013.02.002",
language = "English",
volume = "14",
pages = "95--107",
journal = "Ecological Complexity",
issn = "1476-945X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Harvesting, census timing and "hidden" hydra effects

AU - Hilker, Frank

AU - Liz, Eduardo

PY - 2013/6

Y1 - 2013/6

N2 - Population control in some form of harvesting might be expected to reduce population size, but quite the opposite can happen due to the hydra effect. This phenomenon describes an increase in population size with increased mortality. One mechanism causing hydra effects is the temporal separation of (i) harvesting and (ii) density-dependent reproduction. Here we consider discrete-time models of these two processes. It is commonly believed that harvesting needs to precede reproduction for a hydra effect to occur. We show that, by contrast, hydra effects also take place for harvest after reproduction. Due to the timing of population census, however, the hydra effect will not be measured and thus remains ‘hidden’. As a consequence, managers may miss out on the opportunity to increase both the yield and the remaining stock of renewable resources. If harvesting aims at controlling pest species, management interventions may backfire in the sense that the pest increases rather than decreases—and, to make things even worse, this may actually go unnoticed. To remedy these undesirable consequences, we propose a modelling framework that can reveal hidden hydra effects. Our results are based on rigorous mathematical proofs that the order of two events does not matter for standard harvesting/hunting strategies.

AB - Population control in some form of harvesting might be expected to reduce population size, but quite the opposite can happen due to the hydra effect. This phenomenon describes an increase in population size with increased mortality. One mechanism causing hydra effects is the temporal separation of (i) harvesting and (ii) density-dependent reproduction. Here we consider discrete-time models of these two processes. It is commonly believed that harvesting needs to precede reproduction for a hydra effect to occur. We show that, by contrast, hydra effects also take place for harvest after reproduction. Due to the timing of population census, however, the hydra effect will not be measured and thus remains ‘hidden’. As a consequence, managers may miss out on the opportunity to increase both the yield and the remaining stock of renewable resources. If harvesting aims at controlling pest species, management interventions may backfire in the sense that the pest increases rather than decreases—and, to make things even worse, this may actually go unnoticed. To remedy these undesirable consequences, we propose a modelling framework that can reveal hidden hydra effects. Our results are based on rigorous mathematical proofs that the order of two events does not matter for standard harvesting/hunting strategies.

UR - http://www.scopus.com/inward/record.url?scp=84877110792&partnerID=8YFLogxK

UR - http://dx.doi.org/10.1016/j.ecocom.2013.02.002

U2 - 10.1016/j.ecocom.2013.02.002

DO - 10.1016/j.ecocom.2013.02.002

M3 - Article

VL - 14

SP - 95

EP - 107

JO - Ecological Complexity

JF - Ecological Complexity

SN - 1476-945X

ER -