A Theory of Stochastic Harvesting in Stochastic Environments

Jonzén, Niclas; Ripa, Jörgen; Lundberg, Per

doi:10.1086/339456

Cited by 58 publications

(7 citation statements)

References 50 publications

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“…It was straightforward that when fishing intensity was above a certain threshold (around 50% of the maximum value for both the eastern Skagerrak and Kattegat), the abundance of adult cod was depressed, irrespectively of the recruitment strength. Thus, the results of our study largely confirm recent theoretical applications and, as stated by Jonzén et al (2002b), call for a reconsideration of the role of harvesting as a stochastic process and potential source of population variability.…”

Section: Discussionsupporting

confidence: 88%

“…However, it has been recently demonstrated that for several commercially exploited populations harvesting mortality can explain most of the population variability (i.e. Jonzén et al, 2002b). As highlighted by Jonzén et al (2002b) in a theoretical study, harvesting may explain a considerable proportion of the variation in population density if the mean harvest rate is high and the magnitude of its variance is comparable to or larger than that of the environment.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Modelling recruitment and abundance of Atlantic cod, Gadus morhua, in the eastern Skagerrak–Kattegat (North Sea): evidence of severe depletion due to a prolonged period of high fishing pressure

Cardinale

Svedäng

2004

Fisheries Research

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Modelling recruitment and abundance of Atlantic cod, Gadus morhua, in the eastern Skagerrak–Kattegat (North Sea): evidence of severe depletion due to a prolonged period of high fishing pressure

Cardinale

Svedäng

2004

Fisheries Research

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“…However, by examining survival and yields over different timeframes and harvesting strategies this work presents a novel and a useful perspective on wild meat harvesting under uncertainty. Secondly, using a relatively simple analytical model such as the Beverton-Holt model provides certain advantages over stochastic simulation studies [53,66,67], such as more generalisable, robust conclusions that capture the most salient features of population dynamics useful for exploring system sensitivity to different parameter values and guiding more detailed simulation studies of particular situations [32,65]. Other population models could easily be used instead of the Beverton-Holt model [68], and employing different models would allow model uncertainty (ignored here) to be addressed.…”

Section: Plos Onementioning

confidence: 99%

Modelling parameter uncertainty reveals bushmeat yields versus survival trade-offs in heavily-hunted duiker Cephalophus spp.

et al. 2020

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Reliably predicting sustainable exploitation levels for many tropical species subject to hunting remains a difficult task, largely because of the inherent uncertainty associated with estimating parameters related to both population dynamics and hunting pressure. Here, we investigate a modelling approach to support decisions in bushmeat management which explicitly considers parameter uncertainty. We apply the approach to duiker Cephalophus spp., assuming either a constant quota-based, or a constant proportional harvesting, strategy. Within each strategy, we evaluate different hunting levels in terms of both average yield and survival probability, over different time horizons. Under quota-based harvesting, considering uncertainty revealed a trade-off between yield and extinction probability that was not evident when ignoring uncertainty. The highest yield was returned by a quota that implied a 40% extinction risk, whereas limiting extinction risk to 10% reduced yield by 50%-70%. By contrast, under proportional harvesting, there was no trade-off between yield and extinction probability. The maximum proportion returned a yield comparable with the maximum possible under quota-based harvesting, but with extinction risk below 10%. However, proportional harvesting can be harder to implement in practice because it depends on an estimate of population size. In both harvesting approaches, predicted yields were highly right-skewed with median yields differing from mean yields, implying that decision outcomes depend on attitude to risk. The analysis shows how an explicit consideration of all available information, including uncertainty, can, as part of a wider process involving multiple stakeholders, help inform harvesting policies.

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“…External forcing may also include anthropogenic sources as well as environmental. Under the right conditions, variable fishing pressure has been shown to drive perturbation in the abundance of exploited populations directly (Jonzen et al, 2001(Jonzen et al, , 2002.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence of size‐selective harvest and environmental stochasticity effects on population demography, fluctuations and non‐linearity

et al. 2023

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Theory and analyses of fisheries data sets indicate that harvesting can alter population structure and destabilise non-linear processes, which increases population fluctuations. We conducted a factorial experiment on the population dynamics of Daphnia magna in relation to size-selective harvesting and stochasticity of food supply. Harvesting and stochasticity treatments both increased population fluctuations. Timeseries analysis indicated that fluctuations in control populations were non-linear, and non-linearity increased substantially in response to harvesting. Both harvesting and stochasticity induced population juvenescence, but harvesting did so via the depletion of adults, whereas stochasticity increased the abundance of juveniles. A fitted fisheries model indicated that harvesting shifted populations towards higher reproductive rates and larger-magnitude damped oscillations that amplify demographic noise. These findings provide experimental evidence that harvesting increases the non-linearity of population fluctuations and that both harvesting and stochasticity increase population variability and juvenescence.

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A Theory of Stochastic Harvesting in Stochastic Environments

Abstract: A theory of stochastic harvesting in stochastic environments

Cited by 58 publications

References 50 publications

Modelling recruitment and abundance of Atlantic cod, Gadus morhua, in the eastern Skagerrak–Kattegat (North Sea): evidence of severe depletion due to a prolonged period of high fishing pressure

Modelling recruitment and abundance of Atlantic cod, Gadus morhua, in the eastern Skagerrak–Kattegat (North Sea): evidence of severe depletion due to a prolonged period of high fishing pressure

Modelling parameter uncertainty reveals bushmeat yields versus survival trade-offs in heavily-hunted duiker Cephalophus spp.

Experimental evidence of size‐selective harvest and environmental stochasticity effects on population demography, fluctuations and non‐linearity

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