PONE-D-20-16287

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

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Your manuscript presents an important contribution to the literature on bushmeat harvest, though the methods are also applicable in other harvest contexts as well as other modeling estimation contexts. Below you will find comments from two reviewers that should help in your revisions. 

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T.B. was funded by the Natural Environment Research Council (NERC), grant number NE/L002485/1, https://nerc.ukri.org/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.'

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Reviewers' comments:

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Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

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Reviewer #1: Dear authors

Congratulations for a nicely designed robust study on the impact of uncertainties in the estimation of sustainable offtake for duiker species. I believe this is a very good contribution to the body of research on sustainable hunting as well as something that could be used by practitioners for other species or places.

I have no major comments to make on the paper, the methods are well explain and statistically sound to me and the conclusions reflect faithfully the findings. Useful comparisons are provided with existing studies and show the value of the proposed approach.

This is beyond the scope of the present paper but I think the next step should be to look at the "scale" issue and how hunting is done. This might have a strong influence on expected sustainable yield. You hint on these issues L178-L181 about the many ways harvesting effort can be altered and L434-441 about the issue of scale. I am wondering to which extant it would be interesting to try selecting a very well know species (e.g. roe deer) and test these....

A few notes about references,

[1] is probably not the best one to quote for showing harvesting greater than six times the sustainable harvest rate. Maybe it would be better to refer to the latest analyses provided in https://doi.org/10.17528/cifor/007046

[27,31] are a bit outdated in terms of offtakes too and more recent references could be found in https://doi.org/10.17528/cifor/007046

This of course doesn't change the validity of the paper and of the conclusions

Reviewer #2: This paper addresses an important issue for the sustainable management of data-deficient animals. In the actual world, parameters of animal population dynamics can stochastically vary, and the uncertainty often leads to a different scenario of population dynamics. The authors explicitly incorporate the uncertainty of the parameters (r and K) in the Beverton-Holt population model and apply the model to three species of duikers in Central Africa. The authors revealed that, under quota-based harvesting, there may be a trade-off between yield and extinction probability, which was not evident when not accounting for the uncertainty of the parameters.

The manuscript is well-written and contains sufficient interest and originality to merit publication in PLOS One. However, there are several constraints and issues that should be mentioned explicitly as below.

Major comments

1. The approach presented in the manuscript can be applied to any species, as mentioned in the text. I think this point should be stressed more explicitly. For example, the model details should be explained before mentioning the procedures of actual application to the duikers (in Method section). It is better to regard the application to the duikers as a case study using the more-widely applicable approaches.

2. The approach in the manuscript still has limitations to predict bushmeat yield and extinction probability, although I admit that the authors tried to do the best within the constraints. The authors should specifically mention the limitations in the Discussion. In particular, the following two points should be mentioned.

� The model assumes that the population is spatially closed. However, in real world in central Africa, local people often harvest bushmeat in specific area near village within a large continuous forest. In such environments, the vacant area (i.e. the area where duikers are exhausted) should be rapidly occupied by the surrounding unhunted populations (i.e. source-sink structure). Assuming that immigration/emigration can occur, the extinction risk should be much lower than the results of the simulations.

� The results of the simulations in the manuscript should largely dependent on the distribution that the parameter, r and K follow. The author assumes that the mean and sd of these parameters follow a log-normal distribution. This distribution is relatively fat-tailed, inevitably leading to a larger variance of the estimates. To make more precise predictions, it is critical to accumulate more reliable information on r and K in more fields.

3. The authors said that data on Peters’ duiker is the most limited (L. 256) (some studies may be overlooked. e.g. Nakashima et al. 2018). Given that the parameters of population dynamics are also not likely to largely vary, it may be better to use data on Ogilby’s duiker also, than depending on the very limited data on Peters’ duiker. Recent studies using molecular techniques have shown that they are genetically discriminated (Johnston et al. 2011; Hassanin et al. 2012; Johnston and Anthony 2012) and may be a single species. More information should be available for Ogilby’s duiker.

Minor comments

L62. Information on duikers should be mentioned after the line 77.

L89. Recent studies using molecular techniques have revealed that Peters’s duiker

L90. Recent works use Philantomba monticola as a scientific name of blue duikers instead of Cephalophus monticola.

L121. r = exp(rmax) is correct? In Eq. 4, the authors seem to assume rmax > 0. If so, exp should be removed.

L132. This assumption influences the results. Justify this assumption here.

L142. The ‘n = 1000’ possibly means the number of iterations in the simulation. There is no need to mention here (or add the explanations).

L159. ‘n = 1000’. See above.

L256. See the major comment.

L286 Fig 4 legend. I did not find (B)

L458. I do not always agree with this statement. In central Africa, local people often capture duikers using snares. As long as the capture effort is constant, the harvest amount should be proportional to the duiker density. The results of this study seem to suggest that setting the maximum snare effort may contribute to the sustainable harvesting of duikers.

Figure 2-4 and Figure 5-7 should be integrated into one figure (with three panels), respectively.

The S9 figure largely helped readers to understand what the author actually did. I suggest that this figure moves to the main text (not supplementary).

References

Hassanin A, Delsuc F, Ropiquet A, Hammer C, van Vuuren BJ, Matthee C, Ruiz-Garcia M, Catzeflis F, Areskoug V, Nguyen TT, Couloux A (2012) Pattern and timing of diversification of Cetartiodactyla (Mammalia, Laurasiatheria), as revealed by a comprehensive analysis of mitochondrial genomes. C R Biol 335:32–50.

Johnston AR, Anthony NM (2012) A multi-locus species phylogeny of African forest duikers in the subfamily Cephalophinae: evidence for a recent radiation in the Pleistocene. BMC Evol Biol 12:120–135.

Johnston AR, Anthony NM (2012) A multi-locus species phylogeny of African forest duikers in the subfamily Cephalophinae: evidence for a recent radiation in the Pleistocene. BMC Evol Biol 12:120–135.

Nakashima Y, Fukasawa K, Samejima H (2018) Estimating animal density without individual recognition using information derivable exclusively from camera traps. J of Appl Ecol 55:735-744.

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Reviewer #1: Yes: Robert Nasi

Reviewer #2: No

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

PONE-D-20-16287R1

Dear Dr. Barychka,

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Additional Editor Comments:

Reviewers' comments: