Functional Morphology as an Indicator of European Eel Population Status
, Nevena Kitanović 3, Jurica Jug-Dujaković 4 and Ana Gavrilović 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript "Functional morphology as an indicator of eel population status" has investigated some morphological parameters of the European eel as physiological indicators among yellow and silver life stages.
Studies on the morphological development of this species are challenging, due to the wide variability to which development is subject due to numerous internal and external factors, therefore, in my opinio this work can contribute to the improvement of the state of knowledge, also from a local stock perspective.
Considering this, the work proposes a valid topic, however, I believe that some major revisions must be made in order to accept the manuscript for publication. Authors will find specific comments in the manuscript file
In the introduction, as general comments, I suggest to better explain the link between eel fishing in relation to the need to study the morphology of the species. Second, objectives, as they are presented, are not very clear and underdeveloped, therefore I think it is appropriate to implement this part. To better develop and explain the aims of the paper also using points referring also to the morphological analyses carried out.
Please be consistent with the logical order of methods section and results.
In my opinion, the conclusions lack a final paragraph that highlights the importance of this work, achieved results and new obtained knowledge .
References must be improved
Comments for author File: 
Comments.pdf
For the language I suggest a detailed rereading of the manuscript and attention to typos and spelling errors.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors The great problem of the work is the use o inadequate statistical treatment of the data, which is the core of the work and in my opinion make it unpublishable, and that was what I has referred in my review report and indicate a paper that should be followed to treat the data adequately. However, that would be another work completely different, and my advise is to not accept it.To analyse adequately morphometric data and compare them, it is necessary to properly remove the lenght effect and not only compute ratios with that lenght (see reference below). Therefore, that should be performed before any new attempt of publication of these data.
Costa, J.L., P.R. Almeida & M.J. Costa. 2003. A morphometric and meristic investigation of Lusitanian toadfish Halobatrachus didactylus:: Evidence of population fragmentation on Portuguese coast. Scientia Mar., 67: 219-231.
Comments on the Quality of English Language
Generally ok.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsReview of manuscript entitled "Functional morphology as an indicator of eel population status". The manuscript presents an analysis of eels caught in the Neretva emouth in the southern Adriatic Sea (Croatia). The authors performed a classic fishery biology study. Samples were collected in all seasons and eels were caught with traps typical commercial fisheries. The authors emphasise that this is the first study of measurable characteristics of eel in the world. I have not been able to verify this, but does this mean that they are novel, or rather that they are not very interesting? Why are such classic studies not popular these days? I think that the analysis of measurable characteristics is a valuable attempt to find traits to accurately distinguish between yellow and silver eels.
My overall assessment of this manuscript is positive. However, it should be revised and completed by the authors before acceptance for publication.
Major comments:
The authors easily passed over the issue of sample sizes. Much of the statistical analysis was irrelevant. Perhaps for this reason? Please add a paragraph in the discussion regarding what effect had small sample sizes on the results?
Minnor comments:
l. 12: Write out "fished" instead of “hunted”
l.14: What do you mean by “zero state”? Eel are a well studied species, so it is difficult to indicate that this research meets this criterion.
l.22: Please check the term subpopulations. The European eel has only one population.
l.29-31: Please provide full terms before using abbreviations for the first time.
l.47: ICES has released a more recent report on the subject.
l.121: The threshold values of OI 6.5 set for silver eels were determined by Pankhurst [21]
l.171: The precision of the values presented on the OY axis is too high.
l.194: Condition factor (CF) has no such unit.
l.214-215: What does this mean? The other fish had no gonads?
l.220: Caption for figure 5 needs improvement.
l.230: Please verify the year.
l.294-295: Condition factor has no such unit.
l.321-323: Reference is needed.
l.339-341: In the winter of which year were samples collected?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is adequately integrated with the suggested revisions. The added information made it possible to make the work more readable and more structured, consistently with the objectives. The new statistical analyzes conducted make the results more consistent.
Only, the abstract ends with results. In my opinion, a conclusive part is missing.
Other than that, I have no further reviews to suggest.
Author Response
Dear Reviewer 1,
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral appraisal: The new version of the manuscript improves the previous one but the alterations suggested in the specific comments part should be still introduced before publication.
Specific comments:
Abstract: It should be revised according to what was referred for the other sections.
Lines 217-220: Instead of comparing the indices between the groups using ANOVA tests. it is better to use ANCOVA tests for comparing the raw parameters considering the TL as a covariate.
Lines 221-224: For these analyses, standardized parameters instead of indices should be used also, as for the MDS/ANOSIM analyses, to avoid large lenght influence.
Lines 238-241: Not clear which samples were compared here... Together silver and yellow eels per season? Let clear the rationale, objective of this test and what was tested.
Lines 247-258: Same comments as for lines 238-241.
Figure 6: Useful to mark with different colors/symbols yellow and silver eels.
Lines 342-346: Same comments as for lines 238-241.
Lines 349-356: I strongly advise to remove from the manuscript the data refering to gonads analyses because the laboratory work was not properly done, only allowing to detect females wil developed gonads and not males with developed gonads and not still indifferenciated gonads. Beacuse of that the data presented here is meaningless. Also, given this constraint, GSI should be removed from the manuscript...
Figures 8 and 9 are largely redundant (therefore, only one, probably hierarchical analysis, should be reatined) and would be interesting to have yellow and silver eels in separat groups.
Lines 463-465: That will happen more evidently in a more advanced silver stage.
Lines 475-494: Remove the paragraph as the results analysed derive form a methodological error.
Conclusions: This section is duplicated. It should be revised according to what was referred for the other sections.
Comments on the Quality of English LanguageGenerally ok.
Author Response
Dear Reviewer 2,
Please see the attachment.
Author Response File: Author Response.pdf
