Effects of market price on the dynamics of a spatial fishery model: Over-exploited fishery/traditional fishery

Auger, Pierre; Mchich, Rachid; Raïssi, Nadia; Kooi, Bob W.

doi:10.1016/j.ecocom.2009.03.005

Cited by 34 publications

(23 citation statements)

References 18 publications

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“…In this paper, we propose a general class of models, which demonstrate that the intuitive arguments for the existence of an AAE [10,16] can lead to oversimplified conclusions. While previous studies, using alternative descriptions of market dynamics, demonstrate the possibility of low-density equilibria [2,8], population cycles [7], and even extinction [7,23], our paper reveals previously undiscovered model behavior.…”

Section: Introductionmentioning

confidence: 48%

“…There are a few open-access fishery models that set price as a function of supply, P (qxy), [8,2,24,23] and while none of these models predict an AAE exactly as it is described in classic AAE theory [10], these models do not consider the more general class of price functions studied here. There is strong evidence that price is negatively correlated with species abundance [10,14,1,28,19], but there is also evidence that the price of traded wildlife products decrease with market supply [e.g.…”

Section: Model Limitations Assumptions and Alternative Approachesmentioning

confidence: 99%

“…Unlike most of the models that consider price as a function of demand [8,2,24,23], Burgess et al harvesting more common ones [6]. Models that incorporate multi-species harvest and price abundance relationships have yet to be explored.…”

Section: Model Limitations Assumptions and Alternative Approachesmentioning

confidence: 99%

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High prices for rare species can drive large populations extinct: the anthropogenic Allee effect revisited

Holden

McDonald‐Madden

2017

Journal of Theoretical Biology

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Consumer demand for plant and animal products threatens many populations with extinction. The anthropogenic Allee effect (AAE) proposes that such extinctions can be caused by prices for wildlife products increasing with species rarity. This price-rarity relationship creates financial incentives to extract the last remaining individuals of a population, despite higher search and harvest costs. The AAE has become a standard approach for conceptualizing the threat of economic markets on endangered species. Despite its potential importance for conservation, AAE theory is based on a simple graphical model with limited analysis of possible population trajectories. By specifying a general class of functions for price-rarity relationships, we show that the classic theory can understate the risk of species extinction. AAE theory proposes that only populations below a critical Allee threshold will go extinct due to increasing price-rarity relationships. Our analysis shows that this threshold can be much higher than the original theory suggests, depending on initial harvest effort. More alarmingly, even species with population sizes above this Allee threshold, for which AAE predicts persistence, can be destined to extinction. Introducing even a minimum price for harvested individuals, close to zero, can cause large populations to cross the classic anthropogenic Allee threshold on a trajectory towards extinction. These results suggest that traditional AAE theory may give a false sense of security when managing large harvested populations.

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Section: Introductionmentioning

confidence: 48%

Section: Model Limitations Assumptions and Alternative Approachesmentioning

confidence: 99%

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High prices for rare species can drive large populations extinct: the anthropogenic Allee effect revisited

Holden

McDonald‐Madden

2017

Journal of Theoretical Biology

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“…We used an equilibrium approach. However, transient population declines can occur in harvest models (Auger, Mchich, Raïssi, & Kooi, 2010;Burgess, Costello et al, 2017;Conrad & Lopes, 2017;Holden & McDonald-Madden, 2017;Ly, Auger, & Balde, 2014). This is a valid concern for long lived, slow growing species, where poaching and reproduction happen on vastly different time scales.…”

Section: Discussionmentioning

confidence: 99%

Increase anti‐poaching law‐enforcement or reduce demand for wildlife products? A framework to guide strategic conservation investments

Holden

Biggs

Brink

et al. 2018

CONSERVATION LETTERS

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Donors, NGOs, and governments increasingly invest in campaigns to reduce consumer demand for wildlife products in an attempt to prevent the decline of overexploited and poached species. We provide a novel framework to aid these investment decisions based on a demand reduction campaign's return on investment compared to antipoaching law enforcement. A resulting decision rule shows that the relative effectiveness of demand reduction compared to increased enforcement depends entirely on social and economic uncertainties rather than ecological ones. Illustrative case studies on bushmeat and ivory reveal that campaigning to reduce demand may be more cost‐effective than antipoaching enforcement if demand reduction campaigns drive modest price reductions. The outputs from this framework can link targeted monitoring of wildlife product prices to management decisions that protect species threatened by harvest and trade.

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“…This paper is concerned with the local and bifurcation analysis of the equilibrium point (n * , E * ) of the dynamical system in ( ) 1…”

Section: Introductionmentioning

confidence: 99%

Stability and Bifurcation Analysis of a Fishery Model with Allee Effects

Harun¹

2019

MMA

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We study the equilibrium point (n * , E *) of the fishery model with Allee effect in its population growth dynamics. equilibria points with two being saddles and the other stable and the coexistence of three equilibria points with two being stable and a saddle between them. The equilibrium solutions depicts three kinds of fishery: A fishery with fish population maintained at high levels far from extinction but with little economic activity, a fishery with coexistence of an over-exploited and an under-exploited state, which is a dilemma since neither of the state supports sustainable fish resource exploitation, and a fishery that is well managed with fish population being harvested in a sustainable manner thus a balance between commercial harvesting and species existence.

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Effects of market price on the dynamics of a spatial fishery model: Over-exploited fishery/traditional fishery

Cited by 34 publications

References 18 publications

High prices for rare species can drive large populations extinct: the anthropogenic Allee effect revisited

High prices for rare species can drive large populations extinct: the anthropogenic Allee effect revisited

Increase anti‐poaching law‐enforcement or reduce demand for wildlife products? A framework to guide strategic conservation investments

Stability and Bifurcation Analysis of a Fishery Model with Allee Effects

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