Consideration of reference points for the management of renewable resources under an adaptive management paradigm

Irwin, Brian; Conroy, Michael J.

doi:10.1017/s0376892913000222

Cited by 9 publications

(13 citation statements)

References 54 publications

(99 reference statements)

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“…State‐dependent decision rules of this nature are commonplace for many heavily regulated fisheries (Quinn and Collie , Deroba and Bence , Punt et al ). For example, decision rules where allowable harvest is made more conservative once mortality exceeds some specific value (a decision threshold or trigger; Irwin and Conroy , Nichols et al ) are common in the management of many fisheries (Deroba and Bence ).…”

Section: Discussionmentioning

confidence: 99%

Simulated performance of multi‐year harvest regulation cycles for wild turkeys

2019

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Wild turkeys (Meleagris gallopavo) are a prolific species and valuable game animal throughout the United States. Stochastic simulations are commonly used to inform harvest management, and we used simulation to test performance of fall harvest management that included 1‐, 3‐, and 5‐year cycles of population assessment and updating of harvest targets, respectively. To assess robustness of our conclusions, we replicated analyses across 18 combinations of model parameters that included population productivity (3 levels), sex‐specific vulnerability to fall harvest (3 levels), and magnitude of spring harvest (2 levels). Performance of multi‐year cycles, measured using abundance of males and annual harvest, depended on the context of model parameters that interacted to determine responses of populations to harvest. One‐ and 3‐year cycles had similar performance so long as female harvests were less than or equal to male harvests. However, when harvest of females was greater than males, or when 5‐year regulation cycles were implemented, there was greater risk due to nonlinear population responses to increased harvest. For example, nonlinearity resulted in thresholds where declines to abundance and harvest could occur with small increases to harvest rates, and thus the sustainability of fall harvests was less robust for multi‐year cycles with time‐lagged assessment and decision making. Moreover, the harvest rate resulting in threshold responses depended on model parameters and often occurred within the range of harvest rates recommended by earlier modeling studies (7–15%). Our results imply that multi‐year cycles can be a viable approach to harvest management. Monitoring that provides information on sex‐specific harvest is recommended, however, to determine if nonlinear population responses should be anticipated. Ideally, information on population‐specific vital rates would also be available to allow managers to avoid harvest rates near thresholds that are expected to result in population declines. © The Wildlife Society, 2019

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Section: Discussionmentioning

confidence: 99%

Simulated performance of multi‐year harvest regulation cycles for wild turkeys

2019

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“…A primary goal of reference point development is to ensure reference metrics are indicative of management performance that achieves the underlying objectives (Irwin and Conroy 2013). Reference points have been most formally used for harvest management in fisheries, but their use has been advocated as applicable to a wide range of problems in resource management (MacNeil 2013).…”

Section: Identifying Reference Points For Assessment-limited Populationsmentioning

confidence: 99%

“…Target reference points can serve either as specific targets that management is attempting to achieve, or as indicators of harvests that are inconsistent with management objectives and thus should be avoided (Irwin and Conroy 2013). Target reference points can serve either as specific targets that management is attempting to achieve, or as indicators of harvests that are inconsistent with management objectives and thus should be avoided (Irwin and Conroy 2013).…”

Section: Identifying Reference Points For Assessment-limited Populationsmentioning

confidence: 99%

“…Reference points can be useful as indicators of performance in such cases, whereby a reference point refers to a specific reference level of a simplified metric that indicates performance of management relative to some set of underlying objectives (Irwin and Conroy 2013). Target reference points, for instance, can be used to guide management by indicating performance of a single best policy that management attempts to achieve (e.g., a target harvest rate most likely to achieve objectives), or performance for a set of policies that are robust to uncertainty (e.g., a set of harvest rates with reliable performance in the face of uncertainty; Irwin and Conroy 2013). Reference levels of simple metrics are commonly used to indicate sustainable harvests for assessment-limited wildlife populations Akc ßakaya 2001, Weinbaum et al 2013), although they are not commonly referred to as reference points (phrase comes from fisheries management; MacNeil 2013).…”

Section: Introductionmentioning

confidence: 99%

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Identifying target reference points for harvesting assessment‐limited wildlife populations: a case study

Stevens

Bence

Porter

et al. 2017

Ecological Applications

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Identifying appropriate strategies for sustainable harvest is a challenge for many terrestrial vertebrate species because of uncertain system dynamics, limited data to inform population models, and potentially conflicting objectives that seek to harvest and maintain populations at desirable levels. The absence of monitoring and assessment infrastructure needed to regularly estimate abundance accentuates this challenge for many species, and limits application of rigorous state-dependent frameworks for decision making that are commonly advocated in natural resource management. Reference points, which define management targets or triggers for changing management, are often used to guide decision-making, but suffer from ambiguity when developed without explicit consideration of uncertainty or trade-offs among competing objectives. We describe an approach for developing unambiguous target reference points for assessment-limited species using structured decision making, and demonstrate the approach to develop target harvest rates for management of fall Wild Turkey (Meleagris gallopavo) harvests in the face of uncertain population and harvest dynamics. We use simulation and decision analyses to identify harvest rates that are optimal for accomplishing explicit management objectives in the face of uncertainty, and harvest rates with robust performance over broad regions of the demographic and harvest model parameter space. We demonstrate that population and harvest parameters commonly uncertain to wildlife managers interact to determine appropriate target harvest rates for Wild Turkeys, and that formally acknowledging a range of plausible values for structurally uncertain parameters results in more conservative target reference points than suggested by previously published studies. The structured decision making framework described here provides a natural conceptual and quantitative framework for extending our approach to develop unambiguous harvest targets for other assessment-limited wildlife populations while formally acknowledging structural uncertainty in system dynamics.

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“…Observational uncertainty can be addressed mechanically by collecting additional data, or statistically, by assuming a specific kind of error distribution for observations (Hilborn & Mangel 1997;Irwin & Conroy 2013). Structural uncertainty, however, is more subtle to detect and difficult to address.…”

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confidence: 99%

The politics, science and policy of reference points for resource management

MacNeil

2013

Envir. Conserv.

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Reference points are specific values related to the state of a resource to which targets and limits for harvest management can be set. Although reference points evolved within fisheries science, they are likely to be widely applicable across a range of ecosystems and environments, as the principles behind their development and implementation apply to any harvested system. This special issue ofEnvironmental Conservationtakes a critical look at the ways in which reference points have been used previously, including the political, scientific and management contexts that have hindered and enabled their implementation. Through these experiences, a range of recommendations are made, highlighting the importance of social context in which biological reference points are developed and in favour of approaches that deal explicitly with uncertainty. When implemented without qualification, reference points have proven effective at preventing fisheries collapse and rebuilding depleted stocks; where they have not, management failures have occurred. Given the social-ecological complexity of fisheries management, the papers in this special issue provide a strong argument for the application of reference points across a range of resource management problems.

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Consideration of reference points for the management of renewable resources under an adaptive management paradigm

Cited by 9 publications

References 54 publications

Simulated performance of multi‐year harvest regulation cycles for wild turkeys

Simulated performance of multi‐year harvest regulation cycles for wild turkeys

Identifying target reference points for harvesting assessment‐limited wildlife populations: a case study

The politics, science and policy of reference points for resource management

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