Freshwater Aquaculture Development in EU and Latin-America: Insight on Production Trends and Resource Endowments
Round 1
Reviewer 1 Report
I appreciate the effort authors have made to compare two rather small players in global aquaculture. This article has good information, but despite that, appears too shallow in the end. I am not sure if this article could be a review (?), also it looks like a small assignment but a strong one. However, the article is balanced in a way that upon improvement it can definitely get published. I feel the authors need to dive deeper and do more job to get it published in sustainability. For that some extra exercises are needed. Also there are some logical concerns I have regarding the presentation of facts. In the uploaded PDF, I have tried to be more specific and constructive to help the authors revamp this manuscript into a full vigour article.
Comments for author File: 
Comments.pdf
Author Response
We are grateful to Reviewer for his/her extensive comments and recommendation on the manuscript. The Reviewer asked the authors to bring several new aspects to the analysis, as well as suggested to turn the manuscript into a review type of paper. Based on the Reviewer’s suggestion we implemented the following changes in the MS:
- We made an attempt to interpret our study as a sector analysis and converted into a review paper. The layout of the MS was changed accordingly, and instead of presenting our analysis in a separate result and discussion section, we used a thematic segmentation.
- The Reviewer asked us to consider climatic zone of countries, when discussing the growth potential of freshwater aquaculture. Instead of focusing only on the climate zone (temperate/subtropical/tropical) of the countries scoped by our analysis, we matched temperature data at country-level with thermal preference of main species produced, so that we could draw more conclusion on i) to what extent the climate conditions in individual countries are optimal for the culture cold-water and warm-water species; and ii) what consequences the climate change (focusing only on global warming) might have on production. A sub-section was devoted to this topic.
- As per the Reviewer suggestion we made a graph illustrating production trends for emerging/candidate species.
- A section was devoted to present the main technologies/farming systems in the two regions.
- Based on an extensive literature review, we analyzed the water footprint of the prevailing systems/technologies in the two regions.
- Some minor modifications were also implemented (e.g. moving texts from the introduction section to other parts of the study)
On the other hand, there are other points raised by the Reviewer which we have not addressed, as the detailed below:
- The Reviewer suggested to involve more data on consumer preference in the Introduction section, as well as to discuss the differences in strictness of regulation environment. He/she raised important points here, which obviously have influence on production trends, but the authors felt that these topics are out of the field of their expertise, and it would require more knowledge in the field to mine in the literature, synthetize information and align it with the scope of the study. We also felt that socio-economic consideration is out of the scope of our study.
- Next to water footprint analysis, the Reviewer also suggested to open discussion on nutrient emission rates of different systems and energy consideration. It would have been interesting to explore this aspect, however, it would require several weeks to conduct a systematic review of quantitative information available in the literature on nutrient and energetic efficiency of Latin American farming systems. Contrary to water use, these topics seem slightly out of the topic of our analysis, since it is rather focused on the water resources available for the production. If the Reviewer still has the view that these aspects are necessary for a complete review, we are ready to further work in relation to this, given that the necessary time is provided us by the journal.
We look forward to respond to any further questions and comments you may have.
Reviewer 2 Report
In this work, Cubillos et al. focuses on aquaculture (freshwater fish farming) in the EU and Latin America and Caribbean (LAC).
The Title is suggestive and well stated, however the Abstract has to be made in a more clear and concise form.
Introduction
Line 52,53: Please state why Tilapia is the preferred species in the LAC, also please state which species of Tilapia is most commonly farmed and exported from LAC (perhaps Oreochromis niloticus ? ).
Due to different legal regulations between the two areas, specific aquaculture techniques should be mentioned. A few paragraphs about fish farming techniques should be added, and which are preferred (for example RAS uses in Europe and LAC). Does LAC aquaculture use more antibiotics than the EU aquaculture? or is CuSO4 prefered?
Line 231-232: “EU aquaculture is heavily concentrated on two species. Predatory Rainbow trout and omnivorous Common carp account for 83% of the region’s production.” Is there a reason for that? If so, please specify.
Line 242: “…African catfish which is cultured in high densities with low unit costs are sold at significantly higher prices than low-value cyprinids” currently there’s an serious issue with this invasive species as it ended up in the Black Danube and the status might be changed to “banned” in regards to fish farming. [1,2]
Overall, a good work with only a few minor issues that need to be addressed.
References
1. https://newsbeezer.com/romaniaeng/anyone-who-owned-the-african-catfish-found-in-the-danube-delta-considered-it-a-danger-to-the-local-fauna/
2. Piria M, Jelkić D, Gavrilović A, Špelić I, Opačak A and Ozimec S (2019). First record of North African catfish (Clarias gariepinus) in Croatian inland waters. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00142
Author Response
We thank the respected reviewer for his/her valuable comments and suggestions on our manuscript. Here is a point-by-point response to the reviewers’ comments and concerns:
The Title is suggestive and well stated, however the Abstract has to be made in a more clear and concise form.
Thank you for this suggestion. The abstract was completely rewritten, because the scope and type (original article-> review) of the study changed. In line with this, the title of study was also changed somewhat.
Please state why Tilapia is the preferred species in the LAC, also please state which species of Tilapia is most commonly farmed and exported from LAC (perhaps Oreochromis niloticus ? ).
Where Nile tilapia (O. niloticus) is reported as such, we indicate in the text. However, many of the Latin American countries do not break down statistical reports at species level, indicating only “Tilapias nei” in their report. This may include Nile Tilapia, Blue Tilapia, Mozambique Tilapia and Redbreast Tilapia. But it is assumed that majority of Tilapia nei (Tilapia not specified) is also Nile Tilapia. This is similar to the reporting customs of sturgeon farming in Europe. Statistical reports of many countries do not provide an overview of different species. Based on this reviewer suggestion, we made the sector analysis clearer in terms identification of species discussed by adding an Appendix table presenting the Latin names of major species farmed in the two regions.
Due to different legal regulations between the two areas, specific aquaculture techniques should be mentioned. A few paragraphs about fish farming techniques should be added, and which are preferred (for example RAS uses in Europe and LAC). Does LAC aquaculture use more antibiotics than the EU aquaculture? or is CuSO4 prefered?
A complete section (4.1) was added on the major farming technologies/systems in both regions. Difference in regulatory environment is mentioned in the paper, but it was not the objective of this paper to scope socio-economic and institutional influences on aquaculture, given the lack of expertise of authors in this field.
“EU aquaculture is heavily concentrated on two species. Predatory Rainbow trout and omnivorous Common carp account for 83% of the region’s production.” Is there a reason for that? If so, please specify
European freshwater pond aquaculture has evolved around centuries old tradition of farming carp, and since the XIX. century, farming of rainbow trout is also traditional. This implies that concentration of EU aquaculture on these two species is determined by traditions, but we tried to exclude social factors from our analysis, as mentioned above, so discussion on the role of cultural influences were discussed.
“…African catfish which is cultured …..” currently there’s an serious issue with this invasive species as it ended up in the Black Danube and the status might be changed to “banned” in regards to fish farming. [1,2]
Thank you for this suggestion. We indicated ecological concerns over culture of Claridae sp., with reference to https://doi.org/10.25225/jvb.22008
We look forward to respond to any further questions and comments you may have.
Reviewer 3 Report
This paper provides a comparative overview of decadal changes in aquaculture production for LAC and EU27. All data employed are readily available but usefully combined.
The following provide minor comments on the manuscript and suggestions for improvement in the discussion section.
Introduction:
Line 48: include per capita consumption for EU-27
Line 112: were
Include a precise reason for undertaking the study and why the EU27 and LAC were selected.
Results:
Line 162: …was much higher when compared to other globally important producers. In Peru,….
Line 166: …in the LAC region…
Line 167: …regions, aquaculture in the EU has stagnated over the last decade;…
Line 173: delete LAC from figure legend.
Line 176: state the decade(s) under consideration
Line 209: Salmonids account for over 10% LAC production in your figure.
Lines 223, 234, 235, 290, 300, 301, 302: use lower case for fish names (e.g., carp, trout, sturgeon).
Discussion:
Line 307-310: check these statements since organic agriculture has experienced significant growth as has the cultivation of insects. As inidicated in the second paragraph aquaculture production is limited only by water (quality and availability) rather than land, since production through low to zero-exchange recirculating systems precludes need for water courses (lakes, ponds, rivers etc.) or high quality land.
Line 332: contributes more than…
There should be discussion relating to differences in energy consumption somewhere, especially when considering RAS-based systems. Perhaps under section 4.2.
Line 351: larval rearing and fast growth.
Line 375: lower case w for world.
Line 382: given not giving.
Line 397: full stop between systems. This..
Line 419: delete full stop after fell.
Discuss potential reasons for the increased species diversification and differences between Europe and LAC. Is there an impact of immigration, or changes in religiosity, for example? Have there been innovations in hatchery technology allowing for production of certain species? etc.
Does your study actually provide any insight to enable predictions about future aquaculture development in LAC and EU27? Develop this side of the discussion.
Author Response
We thank the respected reviewer for his/her valuable comments and suggestions on our manuscript. Here is a point-by-point response to the reviewers’ comments and concerns:
Line 48: include per capita consumption for EU-27
We have inserted data on EU fish consumption into the respective section
Include a precise reason for undertaking the study and why the EU27 and LAC were selected.
Thank you for this remark. We tried to be more specific in the context and focus of the study. However, selection of the regions was made based on personal motivation of the authors to have a systematical overview of the aquaculture development in their native region.
Line 307-310: check these statements since organic agriculture has experienced significant growth as has the cultivation of insects. As inidicated in the second paragraph aquaculture production is limited only by water (quality and availability) rather than land, since production through low to zero-exchange recirculating systems precludes need for water courses (lakes, ponds, rivers etc.) or high quality land.
The statement referred (“fastest growing”) was deleted because in fact it was misleading. It was originally meant to refer to the fact that since 1980, the annual growth (~8.2%) in aquaculture has been far above the average annual growth rate (2-4%) in the major terrestrial meat and crop production sectors.
There should be discussion relating to differences in energy consumption somewhere, especially when considering RAS-based systems. Perhaps under section 4.2.
Thank you for this suggestion. A single mention on energy efficiency of RAS was inserted (“…the main advantage of these systems is reduced nutrient emission, but there are some disadvantages that limit development of Ras culture such as high capital cost and worse energy efficiency due to automation….”) .
Although it was suggested both by Reviewer 1 and 3 that a discussion on energy footprint of different systems would be interesting to explore, we felt that it required such an extensive literature mining and data synthesis, that would not fit into timeframe (10 days which was already extended two times) provided for major revision. Please note that that separate section (4.1) was added for comparing different systems in LAC and EU and their water footprint, in addition to several other changes implemented (e.g a section on climate conditions was also inserted).
Discuss potential reasons for the increased species diversification and differences between Europe and LAC. Is there an impact of immigration, or changes in religiosity, for example? Have there been innovations in hatchery technology allowing for production of certain species? etc.
Based on statistical data we added a new section on emerging species, but even here we focused on the production side. During the revision of this manuscript, we tried to narrow down the scope of the study and concentrate our effort on areas the authors are familiar with in terms of expertise. Reflecting this intention, we added a statement into the conclusion section: “This study was not written with the objective to discuss socio-economic influences that may limit the exploitation of resources, rather it concentrated on production trends and underlying factors endowments as available from aggregate statistics.”
Does your study actually provide any insight to enable predictions about future aquaculture development in LAC and EU27? Develop this side of the discussion.
Thanks for this comment. Although we did not apply mathematical modelling that would enable us to provide quantitative forecasts, we tried to insert qualitative /categorical statements which has implication for future growth (species, climate change, water availability).
In addition to the above comments, all grammatical errors pointed out by the reviewers have been corrected.
We look forward to respond to any further questions and comments you may have.
Round 2
Reviewer 1 Report
Thank you for a nice revision, given the time limit of MDPI journals. I agree with the changes you have made. I only have a minor point, which might also increase the citation of this work.
You wrote:
- Next to water footprint analysis, the Reviewer also suggested to open discussion on nutrient emission rates of different systems and energy consideration. It would have been interesting to explore this aspect, however, it would require several weeks to conduct a systematic review of quantitative information available in the literature on nutrient and energetic efficiency of Latin American farming systems. Contrary to water use, these topics seem slightly out of the topic of our analysis, since it is rather focused on the water resources available for the production. If the Reviewer still has the view that these aspects are necessary for a complete review, we are ready to further work in relation to this, given that the necessary time is provided us by the journal.
My answer: maybe put some texts in these regards by narrowing down your choices taking some model systems- ponds? trout farming? Give only N, P. GHG emissions (whatever you could get)?
Leave energy-emergy considerations for now (do a separate review later).
Author Response
We thank the Reviewer for all her/his suggestions to improve the manuscript. As per the review report 2. suggestion, we included a new chapter (no. 5) in the re-submitted draft where carbon footprint and nutrient emissions of different systems/species are discussed.