Assessing the Relative Vulnerability of Chondrichthyan Species as Bycatch Using Spatially Reported Catch Data Series

Round 1

Reviewer 1 Report

Comments

1.      The manuscript’s subject matter is suitable for the journal Animal Diversity, and the manuscript is a valuable contribution to the literature. Therefore, I recommend its publication following revision based on the comments below.

2.      In claiming their approach is novel (i.e., it does not simply follow a method established in the literature), the authors should specify how their approach and results differ from the common approaches of other studies. The keywords “risk assessment” and “vulnerability assessment” suggest their method might be ‘ecological risk assessment’ as applied in the literature to the effects of fishing stressors, and ‘vulnerability analysis’ as applied widely to evaluate risks from the impacts of climate change stressors, respectively.

The analysis applied by the authors resembles a productivity-susceptibility analysis (PSA). The authors state (lines 178‒181) that “species resilience” approximates the biological parameters of r, k, and t_m, the same as ‘productivity’ in PSA. In my opinion,  the authors diminish their approach by including MSY as an additional parameter derived from the Catch-MSY method described in reference 24. There is no theoretical basis for relating MSY to catch. Both catch and MSY are likely to be high for species of high biomass and low for species of low biomass, which implies observations are correlated rather than causal. Note that the scatter of these observations is wide in reference 24, indicative of catch being a poor predictor of MSY. The maximum sustainable yield rate (MSYR), defined as MSY/B_MSY (Butterworth and Punt; 1995), is a better quantity to represent productivity risk. The second component of PSA is ‘susceptibility’, incorrectly specified as the average of the attributes ‘availability’, ‘encounterability’, ‘selectivity’, and ‘post-capture mortality’ in references 28 and 30, but correctly specified as the product of these four attributes in reference 15. Values determined for ‘susceptibility’ are highly sensitive to the calculation method (i.e., average versus multiplication) (see https://doi.org/10.1071/MF21141). The ‘fishery interaction index’ provides very accurate estimates of availability x encounterability, but the authors do not explicitly account for the selectivity of the fishing gear or post-capture mortality. Nevertheless, they can argue that selectivity risk and post-capture mortality risk approach 1.0, given that most fishing gear deployed in the SESSF (trawl and hooks) are non-size selective, and most animals caught die. Conversely, gillnets are highly size selective but are used mainly in depths less than 75m.

3.      The terms “risk”, “vulnerability”, and “resilience” need careful definitions to avoid confusing the reader. The expression “catch intensities” is unusual without established meaning in the literature. I suggest considering the well-established expression ‘fishing intensities’.

4.      When comparing their results with those from other studies, the authors should note that several species they investigate received highly quantitative stock assessments. Also, a more general vulnerability analysis of the chondrichthyan species of southern Australia exists that incorporates the elements of PSA (see https://doi.org/10.1111/faf.12571). However, this PSA framework transitions to the vulnerability analysis framework (i.e., vulnerability = exposure x sensitivity x adaptability, a framework embraced by the Intergovernmental Panel on Climate Change). A recent study evaluating risk from lacking management actions also adopts the vulnerability framework (see https://doi.org/10.1111/faf.12695) rather than the PSA framework.

5.      Many of the IUCN extinction risk categorizations in Table 2 need updating. For the present manuscript, Galeorhinus galeus increased from VU to CR, Deania calcea from LC to NT, Isurus oxyrinchus from VU to EN, and Cephaloscyllium albipinnum from NT to CR.

6.      Given “chondrichthyan species” appears in the title, I suggest mentioning in the Abstract and Methods that no rays and only one chimaera species were in the analysis.

7.      In line 130, consider altering “represented” to ‘reduced the number of records to’.

8.      In line 406, 1950s’ should be 1950s.

9.      In line 313, “1,2m” should be ‘1.2m’.

10.  In line 456, “due its flexibility” should be ‘due to its flexibility’.

Suggested reference

 

Butterworth, D. S., & Punt, A. E. (1995). On the Bayesian approach suggested for the assessment of the Bering–Chukchi–Beaufort Seas stock of bowhead whales. Report of the International Whaling Commission, 45, 303–311.

The quality of the English Language is good.

Author Response

Paper: Assessing the relative vulnerability of Chondrichthyan species as bycatch using spatially reported catch data series

First and foremost, We’d like to thank greatly to our reviewer for the insightful and constructive comments in order to improve our work and raising the quality to the level of an esteemed journal such as Diversity.

Please find attached the file with our changes made according to your comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Good paper no comments or suggestions from me.

Author Response

First and foremost, We’d like to thank greatly to our reviewer for the compliment about our study. 

We hope you can still agree with its quality after the changes proposed by the other reviewers.

Author Response File: Author Response.pdf

Reviewer 3 Report

Report of the manuscript diversity-2350124

The manuscript entitled "Assessing the relative vulnerability of Chondrichthyan species as bycatch using spatially reported catch data series" describes the method termed by authors as Fisheries Interaction Index aimed to prioritize the quantify the management of different Chondrichthyan species caught bycatch. Considering the author's proposal, it is plausible to understand their suggestion; however, at the same time, the method is inoperant in countries without the required information to develop the method. It is advisable to consider the publication after major and minor concerns clarifications.  

MAJOR CONCERNS

Is it valid to calculate resilience according to the study' proposal? Please justify, not for the reviewer, but for the reader.

Are there mathematical models where Chondrichthyan species' movements have been documented to validate the information from the maximum sustainable yield (MSY) interpolation?

Did the species of commercial interest and their volume in the different fishing efforts influence the number of cartilaginous fish caught bycatch?

Would it be appropriate to enter this information in the index? Please include or clarify this information, not for the reviewer but for the readers.

MINOR CONCERNS

Introduction

It is also advisable to cite many countries where these Chondrichthyan species are used as food for human, regardless of the uses mentioned in the manuscript (lines 38-41). The information contained in lines 49-50 needs to be more!

Methods

Despite appearing to be a commonly used methodology, information on the calculation of k in the von Bertalanffy growth specific information should be included.

Results

lines 250-257: Check the units!

Author Response

First and foremost, We’d like to thank greatly to our reviewer for the insightful and constructive comments in order to improve our work and raising the quality to the level of an esteemed journal such as Diversity.

Please find attached the file with the specific reply to your insightful comments.

Author Response File: Author Response.pdf