The Spatial Variation of Acoustic Water Column Data and Its Relationship with Reef-Associated Fish Recorded by Baited Remote Underwater Stereo-Videos off the Western Australia Coast

Round 1

Reviewer 1 Report

Brief summary

This study aimed to investigate the possibility of combining echosounders and Baited Remote Underwater stereo-Videos (stereo-BRUVs) in providing more holistic information on the distribution of demersal and semi-demersal reef associated fish.

Spatially explicit information on coral fish species abundance and distribution is required for effective management. Non-extractive techniques, including echosounders and video census, can be particularly useful in marine reserves where the use of extractive methods is restricted.

The results showed high correlations between the acoustic and stereo-BRUVs data in the CS suggesting the potential use of both for a better estimation of biomass in the area. The results for the NMP showed weaker correlations between the two datasets, and highlighted the high variability of the system. Findings suggest a potential benefit of combining both techniques in the reef associated fish distribution assessment.

General comments

I enjoyed the manuscript. All parts are well described and well framed and the objectives were achieved with the experience, and the analysis of the results seems to be adequate. This work is useful in view of the need to find less destructive and non-extractive sampling methodologies, in particular to be applied in reserve areas for example or to monitor conservation endangered species. It is not clear in the methodology at which depths the stereo-BRUV samplings were performed in both sites and other basic information are missing. Perhaps a Table resuming all samples characteristics, including a summary statistic of the measured variables, would be useful to better inform those who read the manuscript. Throughout the text the word "non-destructive methods" is used. Given the context, it might be more appropriate to use "non-extractive methods" since extractive monitoring methodologies are not always destructive.

Finally, the work is in my opinion ready to be published as it is.

Author Response

I enjoyed the manuscript. All parts are well described and well framed and the objectives were achieved with the experience, and the analysis of the results seems to be adequate. This work is useful in view of the need to find less destructive and non-extractive sampling methodologies, in particular to be applied in reserve areas for example or to monitor conservation endangered species. It is not clear in the methodology at which depths the stereo-BRUV samplings were performed in both sites and other basic information are missing. Perhaps a Table resuming all samples characteristics, including a summary statistic of the measured variables, would be useful to better inform those who read the manuscript. Throughout the text the word "non-destructive methods" is used. Given the context, it might be more appropriate to use "non-extractive methods" since extractive monitoring methodologies are not always destructive.

Finally, the work is in my opinion ready to be published as it is.

R: Agree, we have changed the word non-destructive to non-extractive.

We have added a table with a summary of the main variables studied in the two study areas. L681-684

Reviewer 2 Report

GENERAL COMMENTS

This is an interesting study about the use of non-extractive techniques and their potential combination, in order to provide more acute and detailed information on the spatial distribution of reef fish, for aiding fish conservation and management. The manuscript is overall well-written and structured, however, I do found a series of points that need improvement by the authors, starting with the title, and going through the objectives (need to be better stated), description of the study area (rather than pointing to other studies), and also Results (specification of correlations, statistics and numbers are clearly needed). Below is a list where these and others comments are listed, should the authors want to use them to improve their manuscript.

 

SPECIFIC COMMENTS

L1 – I do not like the word “Investigating” in the title as it is a redundant word. Also “of reef associated fish off” does not sound well. Also, I believe “off” should be replaced by “of”.

L46-48 – But what are the advantages of these methods relative to the others?

L86-91 – Do not present these objectives in a form of isolated paragraphs. Put them in the text, for example like this: i) Evaluate the spatial distribution…; ii) Evaluate the spatial distribution… and iii)…

Finally, and most important, end the paragraph by stating why this (the findings of your study) can be important for science and management of MPAs.

L96 – CS?

L96 and throughout the manuscript: replace”off” by “of”.

L97-98 – Please describe your study area, do not point the readers to other studies. The same for L102-105.

L99-100- What are the habitats? What is the composition/structure of the fish assemblage? What was the area monitored? Mean depth?...

A full description of both studies areas in terms of area, depth and other physical variables, as well the fish assemblages is needed.

L123 – Provide brand and model for the video cameras.

L129 and L142 – Please avoid using the same exact sub-titles as above (L95 and 101, respectively).

L241-250 – This is too vague. Please provide numbers, values…How higher? How lower? Be specific. Any test for significant differences?

L261 – Provide statistics.

L264-267 – Please provide statistics for the correlations.

L266 – Sentence unclear, please –re-write clearer.

L269-273 – Same comment as above, with regard to specifications.

L279-280 – Did you perform any statistical test to support this?

L281-284 - This is too vague. Please provide numbers, values…How higher? How lower? Be specific. Any test for significant differences?

L286-289 – Provide values and statistics for the correlations.

L303-304 – What about the results?

L311-313- Name of the test?

Figures 4 and 5 – please provide units for the axes. What do the blue line and the grey band mean?

Figure 6 – If it is relative abundance, shouldn’t the y-axis scale vary between 0-100 (or 0-1)? Units for the y-axes? The same for Figure 7.

Figure 8a – Same comment as in figures 4 and 5.

L326 – “significant, but not strong correlations” – What you mean by such statement? If they are significant (i.e. P< 0.05), they should be strong correlations.

L334-335 – “perhaps the low sample size was the main reason”. Please avoid speculation. Provide a reference to support your hypothesis, otherwise do not include it.

L364 – Remove “some”.

L375 – “influenced” instead of influence.

L381 – Sentence not clear, please re-write

L423 –has not been well studied. Why? So are your results and conclusions biased?

L463 – Which conditions? Be specific.

 

 

 

 

 

 

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I have now went through the revised version as well as through the author comments to my previous concerns, and I'm overall happy satisfied with both. I believe this version is significantly improved over the previous submission and it now grants publication.

Just a small issue to correct upon the proofs page: please replace "Wilcox" by "Wilcoxon" within  the text.