To Trade or Not to Trade? Using Bayesian Belief Networks to Assess How to Manage Commercial Wildlife Trade in a Complex World

Elizabeth L Bennett,E.J Milner-Gulland,Fiona M Underwood

doi:10.3389/fevo.2021.587896

Elizabeth L Bennett, E.J Milner-Gulland + Show 1 more

Open Access

https://doi.org/10.3389/fevo.2021.587896

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Abstract

International commercial trade in wildlife, whether legal or illegal, is one of the greatest threats to multiple species of wildlife today. Opinions on how to address it are deeply divided across the conservation community. Approaches fall into two broad categories: making the trade illegal to protect against any form of commercial trade or allowing some or all of the trade to be legal and seeking to manage it through sustainable trade. The conservation community is often deeply polarized on which is the better option. We posit that a way to choose between these options is by considering species-specific attributes of biological productivity, management context, and demand. We develop a conceptual framework to assess which option is more likely to result in successful conservation of a species. We show how to construct a Bayesian Belief Network (BBN) to model how these attributes (1) interact to affect the sustainability of the species’ population and (2) vary under different trade management regimes. This approach can support scientifically based decision-making, by predicting the likely sustainability outcome for a population of a species under different trade management regimes, given its particular characteristics and context. The BBN allows identification of key points at which conservation interventions could change the potential outcome. It also provides the opportunity to explore how different assumptions about how humans might respond to different trade regimes affects outcomes. We illustrate these ideas by using the BBN for a hypothetical terrestrial mammal species population and discuss how the BBN can be extended for species with different characteristics, for example, those that can be stockpiled or when there are multiple products. This approach has the potential to help the conservation community to assess the most appropriate regime for managing wildlife trade in a transparent, open, and scientifically based way.

Highlights

Setting the SceneInternational commercial trade in wildlife, whether legal or illegal, is one of the greatest threats to wildlife today (Butchart et al, 2010; Nijman, 2010; Duckworth et al, 2012; Challender et al, 2015; Eaton et al, 2015)
We focus here on terrestrial mammals harvested from the wild for international commercial trade, the general principles apply to other taxa
Some 915 species of terrestrial mammals are listed on CITES Appendix I or II, so are in trade and deemed to require management; approximately 40% of these are on Appendix I, so considered threatened with extinction unless all international commercial trade is prohibited

Summary

INTRODUCTION

International commercial trade in wildlife, whether legal or illegal, is one of the greatest threats to wildlife today (Butchart et al, 2010; Nijman, 2010; Duckworth et al, 2012; Challender et al, 2015; Eaton et al, 2015). The BBN could answer a question such as: for a species with a small population, low productivity, high demand, good management and a trade ban in place, what is the probability that the population can be maintained sustainably? The model that we present here is tentative and preliminary, it captures our key proposition: that by considering the mechanisms by which productivity, demand and management interact, we can investigate how different conditions affect the sustainability of the population and the relative effectiveness of a ban or managed trade for a particular species. If products look similar but have different legal status, it is difficult for managers to ensure that illegal products are not passing along the trade chain This could be included in the BBN by including a node that represents the ease of identifying the species, or product. This current limitation on BBNs does not, undercut the value of the general approach of constructing a BBN and exploring it to investigate the relationships between species productivity, different aspects of management and demand, in order to assess impacts of different policy decisions on the sustainability of species’ populations

DISCUSSION

Findings

DATA AVAILABILITY STATEMENT