Remote Sensing of the Subtropical Front in the Southeast Pacific and the Ecology of Chilean Jack Mackerel Trachurus murphyi
Round 1
Reviewer 1 Report
Title: Remote sensing of the Subtropical Front in the Southeast Pacific and the ecology of Chilean jack mackerel Trachurus murphyi
With the subtropical front playing an essential role in the ecology of the jack mackerel in Chile, and the importance of remote sensing studies, this study identifies gaps in remote sensing studies in the south pacific and identifies major satellite data types useful to locate STF.
Lines 90-96: I wonder whether this is necessary here. Please comply with the author's guide form for this journal.
Author Response
Thank you for your comments. Our response to all 3 reviewers is uploaded.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript reviews studies that investigate the Subtropical Front (STF) using satellite remote sensing (SRS), and relates this to its importance to the Chilean jack mackerel fishery. I feel this is a relevant review for the journal and the research topic, and I particularly commend the authors for utilising research from non-English sources, which as they point out, can leave important sources of data untapped by the research community. I found this an interesting topic and a review of this nature would be value to the research areas of satellite remote sensing and fisheries management. Please note my area of expertise and experience in this field is in conducting systematic maps and linking satellite remote sensing data with ecological data. I do not feel I can comment on the on the use of satellite remote sensing data to obtain frontal data, or on frontal science as a whole, which is a significant part of this review.
However, the review has several major flaws. There is little or no information about the methods used to obtain the articles used in the review, meaning that the study is not reproducible. In addition, have concerns about the overall format and clarity of the review and feel the importance of this study and how it informs future research and the wider scope of SRS and fisheries science is not present. As such, I don’t believe I can recommend this manuscript for publication in its current form.
General Comments
Overall, I found this topic quite hard to follow, particularly section 3. I think it could be reworked to improve clarity. Suggestions on how to do this I have added below. In addition, I think key information normally found in reviews is missing. What are some key next steps for this research for instance? Where are the gaps in knowledge? They are dotted around the text and in the discussion but a section or two in the review, replacing the discussion, could be added directing the reader to this important information. In addition, information on how this review aids this field of research overall, either in merging SRS and ecological data, or how this can be aided to inform fisheries management of other species, is not present.
In many places parts of sentences are italicised. I guess this is for emphasis, but it’s not particularly clear and I suggest that these are removed. There are a lot of similar acronyms which make it hard to read. If they are to be included, I suggest a table of explanations for each acronym, and how they differ (e.g., between STF, STFZ, NSFT, SSFT) would be useful to be included in the text or as supplementary material.
Introduction
I found the introduction well written and easy to understand. The authors gave a good background to the topic and why the review is needed.
Data and Methods
No information is provided on the search methods for the review. Systematic processes for reviews, such as systematic maps, are now commonplace and the gold standard for reviews (https://link.springer.com/article/10.1186/s13750-018-0121-7). I do not suggest that such an in-depth process is necessarily required (however, would be preferred), however significant detail on review methodology is needed before this manuscript could be accepted for publication. I suggest the authors look at the work of Haddaway et al, and this https://www.roses-reporting.com/systematic-map-protocols for further detail on the type of detail that should be included in the methodology, but is currently missing.
Section 3
Rather than highlight information obtained from each article in the review, this could be summarised by key findings or key characteristics of the STF in the southeast Pacific. For a reader it would be much more useful to point to the key frontal characteristics of the STF in this region.
Section 4
This section is structured better for the reader, I suggest the authors use a similar format on section 3, with information from articles informing structured subheadings.
Discussion
I suggest this is broken up and merged with other information from the text into a ‘Gaps in knowledge’ and ‘Key next steps’ sections, or similar. I think this would aid clarity and help the reader get as much information out of the review as possible.
Summary
Detial on why this review is important should be added, along with summaries on any gaps in knowledge and next steps or avenues for research.
Tables and figures
I thought the tables and figures were well detailed and well explained throughout the manuscript. However, there were a lot, perhaps some could be moved to supplementary.
Specific comments and suggested revisions
Trachurus murphyi should be italicised throughout, so double check this, including the abstract.
Southeast Pacific Ocean. Is this a generic directions (point of the compass) or a unique location? If generic then should be southeast Pacific Ocean not Southeast Pacific Ocean.
Line 42 – What is deep blue fisheries? Does this need a reference?
Line 59 – Acronym so name in full.
Line 59 – “In the west, the spatial 58 density of CTD data drops off precipitously east of the Chatham Islands (east of 175°W).” How does this relate to STF?
Comments for author File: Comments.pdf
Author Response
Thank you very much for your detailed and insightful comments. Our responses to all 3 reviewers are uploaded.
Author Response File: Author Response.pdf
Reviewer 3 Report
The review of the Subtropical Front (STF) in the open south Pacific Ocean is opportune. It clarifies the diverse nomenclature utilized and the approaches, particularly those documented by Russian and Ukraine oceanographers. The STF plays a crucial role in the ecology of Chilean jack mackerel, particularly in the spawning and feeding that determine the flow (ontogenetic migration or connectivity) between Chile and New Zealand. Although Elizarov et al. (1993) and Evseenko (1987) summarized most of the findings about the Chilean jack mackerel, I think that the contribution of Konchina et al. (1996) and Konchina & Pavlov (1999) is crucial and deserves to be reviewed.
The authors point out that salinity and fronts (gradients) should be utilized in models (distribution) considering reproductive and feeding stages. Here, authors can connect with Konchina et al. (1996) and Konchina & Pavlov (1999) due to the importance of feeding and the occurrence of strong year classes. Usually, jack mackerel disperse in open waters to spawn, but they aggregate in dense schools for feeding in coastal waters of the southeastern Pacific (Peru and Chile). Mid-water trawl can collect several aggregations over large distances, minimizing the dispersed and small aggregations effects. Nevertheless, the international distant mid-water trawl fleet catches most jack mackerel during spawning migrations to open waters close to the Chilean economic exclusive zone (see Figures 14 and 16). So, the link between jack mackerel ecology and STF emerges on a large scale rather than due to dominant year classes exploring far west and due to an overpopulated jack mackerel during the years 1980. Thus, the distribution is state-dependent, and the abundant year classes are an additional requirement for forecasting for a particular season or year. Nevertheless, I agree that it isn't easy to implement a forecast system without accounting for different strategies utilized by jack mackerel in open waters.
Specific
Authors must review minor typos and errors, mainly scientific names in italics.
Figure 4. The label of currents must be in the legend or caption of the figure.
References
Konchina, Y. V., Nesin, A. V., Onishchik, N. A., & Pavlov, Y. P. (1996). On the migration and feeding of the jack mackerel Trachurus symmetricus murphyi in the Eastern Pacific. Journal of Ichthyology, 36(9), 753-766.
Konchina, Y. V., & Pavlov, Y. P. (1999). On the strength of generations of the Pacific jack mackerel Trachurus symmetricus murphyi. Journal of ichthyology, 39(9), 748-754.
Author Response
Thank you very much for your detailed and insightful comments. Our responses to all 3 reviewers are uploaded.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
General Comments
The authors have put in a lot of work and made significant changes to the manuscript, which has improved it’s contents, quality and readability. They have responded well to all suggestions and provided valid reasons in cases where they did not make suggested changes. I have a few minor suggestions to improve the manuscript but otherwise, subject to consideration of the points raised below, I consider the manuscript is suitable for publication in Fishes.
Introduction
No further additions or changes required.
Data and Methods
The authors have added much of the requested methodological information to improve the transparency and reproducibility of the review. However, although the search engines have been noted, the date range of the searches, have not, and it not entirely clear the exact search terms. It would be clearer if they added the exact Boolean search terms they used, e.g., South Pacific AND Subtropical Front. These terms and date ranges should be added to the manuscript before it is suitable for publication. I assume the DOI and URL provided for each source is in the reference section. It might be helpful, and easier to find for a reader, if these were added to Table 1.
Section 3
I still feel this section could be improved for clarity. Subheadings have improved sections 4 and 5, and if possible I think they should be added to improve the clarity of this section However, the authors have stated their reasons for not altering the structure and I will leave this at the editors discretion.
Section 4
The addition of the subheadings has improved this section. No further additions or changes required.
Discussion
The addition of the subheadings has improved this section. No further additions or changes required.
Data gaps, knowledge gaps, and key next steps
No further additions or changes required.
Conclusions
No further additions or changes required.
Tables and figures
No further additions or changes required.
Specific comments and suggested revisions
Line 129 – Should be ‘websites’.
Author Response
Our replies are uploaded.
Author Response File: Author Response.pdf
