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Thank you for revising your manuscript to address the remaining concerns of reviewer 3. I am satisfied that their comments have been addressed. The manuscript is now ready for publication.
[# PeerJ Staff Note - this decision was reviewed and approved by Xavier Pochon, a PeerJ Section Editor covering this Section #]
Please follow the comments given by reviewers, if you disagree, explain why
thanks in advance.
regards
Through earlier revisions of this manuscript, the authors have improved the readability of the text and characterization of their study. Prior to the most recent revision, they improved reproducibility of their study through reporting of field methods and statistical analysis. In response, I had suggested minor edits to the text to further improve readability. The authors have suitably incorporated those minor edits, and I do not have additional suggestions prior to publication.
As stated in past reviews, the study is relevant, suitable for the field of fisheries research and documents growth and condition of important species in Antarctic waters.
After improved characterization of analyses, readers should find that the authors correctly and accurately assessed growth and condition of these fishes using standard practices.
The second version of the manuscript entitled “Length-weight relationships and condition factors of two congeneric rockcod species from two locations in King George Island, Antarctica” represents a modified version in terms of the statistical analyses used and the conclusions drawn. However, it still contains numerous weaknesses that prevent it from being acceptable for publication in its current form. This is one of the rare cases where the revised version is weaker than the original, despite the changes made.
As it stands, the manuscript is difficult to follow and, at times, hard to read. The English language requires further editing, particularly in terms of sentence structure and syntax. The structure of the Introduction needs to be completely revised. The scientific hypothesis and the main objective of the authors remain unclear.
My recommendation to the authors is to adhere closely to the objectives stated in the title and to remove all unclear or speculative statements from the text. They should use clear and precise statements that are well-supported by the statistical data.
Additional comments are provided directly in the manuscript as in-text comments.
The experimental design is good and well performed.
See the comments in the text.
See the uploaded file.
The referee's comments are provided in the attachment. Please make the necessary adjustments carefully.
**PeerJ Staff Note**: Please ensure that all review, editorial, and staff comments are addressed in a response letter and that any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
This manuscript is clearly and professionally written. I only had minor edits for manuscript text, which I will add to "Additional Comments." I felt the manuscript was supported sufficiently by references. I would recommend additional context could be gained in the Introduction section. While reading, I was curious whether the growth or condition of these species was a concern, or whether one species would exhibit different growth than the other. However, this does not invalidate or affect my ability to interpret the results. The article structure was professional, the tables and figures were improved from the previous draft and are sufficient for publication, and raw data includes all information necessary to examine statistical methods. This manuscript reports conclusions that are fair and within the scope of the data that were collected.
Since the previous draft, the authors improved descriptions of their field and statistical methods. As mentioned previously, the manuscript could benefit from additional justification for the research question and why it is meaningful in the Introduction section. However, I do not think it requires much revision beyond the addition of a small amount of text (not a major issue). All analyses were sound and well-described.
The authors compared their results to similar studies of these species to contextualize their findings. Data have been provided in a transparent and clear format that allows the reader to examine their statistical analyses. Conclusions are appropriate and supported by the experimental design.
I credit the authors for their important work and their improvement of the manuscript through revision. I enjoyed reviewing this manuscript. Below I will add line-by-line comments, which are mostly minor suggestions or edits.
Line 37: Consider using species’ common names throughout the rest of the manuscript after introducing their scientific names here.
Line 55: Change “gender” to “sex”
Line 70: I think each paragraph on their own read well. However, it feels like some connection is missing. Either in this paragraph, or in the first Introduction paragraph, it would be helpful to explain whether LWR and condition of these species is unknown. Further, some hypothesis or prediction would improve the manuscript framing. It could be something along the lines of “we expect these species to be in good condition because ___”, or “scientists are concerned about the condition of these species because ___”, or did you expect one species to have higher growth/condition than the other? Otherwise, the bulk of the introductory text is good.
Line 83: Could you please provide latitude and longitude for these sites?
Line 87: Thank you for adding details about the sampling gear, this helps the reader understand how fish were collected. My only additional question here is whether these traps were deployed on the bottom, or suspended?
Line 97: I think it is acceptable to not compare CPUE, especially if there is a justification for why we need to know more about both species’ growth and condition.
Line 130: This is an improved description of statistical methods relative to the first draft. Thank you for clarification.
Figure 1: I think “pie chart” instead of “phi chart”
Dear Authors,
Your article has been evaluated by referees and a ‘Major revision’ decision has been determined. Please review the referee's suggestions and corrections carefully.
You can see the reviewers' comments on your article below.
This study aims to estimate the LWR and the Fulton’s condition factor of two Antarctic notothenioids, N. coriiceps and N. rossii, sampled from two different locations in Maxwell Bay, King George Island, Antarctic Peninsula to enhance the understanding of the biological and ecological characteristics of these fish populations.
Clear and fluent English is used in this study. Literature references, sufficient field background/context are provided. Professional article structure, figures, tables. Raw data is shared.
Methods described with sufficient detail and information to replicate.Fish samples were collected using pole and line as well as fish traps from January to February 2023 at two sampling locations around King Sejong Station, King George Island, Antarctica.
Rigorous investigation performed to a high technical & ethical standard.For tissue sampling, the fish were exposed to 50 mg/L of MS-222 to perform the procedures under anesthesia. After the experiment, the remaining fish were euthanized using 200 mg/L of MS-222 in accordance with animal experimentation ethics.
Research question well defined, relevant and meaningful.
Finaly, original primary research within Aims and Scope of this journal.
mpact and novelty not assessed. Meaningful replication encouraged where rationale & benefit to literature is clearly stated.
All underlying data have been provided; they are robust, statistically sound.
Conclusions are well stated, linked to original research question and supporting results
no comment
This was an interesting manuscript characterizing the authors’ efforts to assess the growth and condition of two rock cod species near Antarctica. I appreciate the effort and coordination required to conduct field sampling for this study.
I felt the writing was generally clear and strong throughout the manuscript. Overall, necessary citations accompanied the text in all sections. The Introduction section was very short, lacked necessary details and could be lengthened to better describe the relevance and purpose of the study, along with describing the knowledge gap the authors aim to fill with this publication. The structure of the article was acceptable, outside of the Methods section, which I will describe later in the review. Figures and tables were a good start but could use improvement for publication. I was able to access the data associated with the manuscript, but I could not evaluate the statistical analyses sufficiently because they were not included in the submission. This manuscript was self-contained and included most of the relevant analyses and results to explore the growth and condition of Antarctic rock cod.
1. Lines 47 – 50. To this point, the authors sufficiently described the species, their habitat, and the history of their exploitation. However, there is likely a need for another paragraph to connect the status of these species, their habitat, their exploitation and how that could affect their growth and condition. For example, if there is evidence that one of two species was overexploited, would that affect their growth (i.e., overfishing can lead to smaller individuals with earlier maturation)? Considering condition, does this particular habitat have a sufficient prey source for both species to be in good condition? Some of this information may be missing in the literature to support a hypothesis, but at least identifying potential reasons to necessitate this study would improve its relevance.
5. Figure 2. I suggest using two colors: one for each species. Indicate in figure legend that black points represent individual observations (I think).
6. Figure 3. I would consider adjusting all y-axes to range from 0 – 100.
7. Figure 4. In the pdf format I downloaded, this figure has low image quality and it is difficult to evaluate. I suggest saving at a higher resolution, or avoiding using screen shots if that was how the image was saved. I would also again consider using two colors, consistent with Figure 2, then adding a legend that denotes which point shape represents each sampling site.
8. Figure 5. I suggest changing x-axis to sites, then using the same two colors for each species. Include in figure legend at + sign represents mean K for each bar. Like Figure 2, I suggest including observations as black points.
9. Figure 6. Similar to Figure 4, this figure appears to have low image quality. See above for suggestions on how to improve image quality. Here I see benefit in four colors, but there is probably a way to reduce to two colors (one per species) consistent with other figures if different bar types (e.g., dashed vs. solid) are used.
The design of this study was sufficient and reflected common methods for evaluating fish growth and condition. Where described, the applied statistical analyses were sufficient to compare growth and condition among sites and species. However, in this submission I found reporting to be insufficient for evaluation and replication. Statistical methods were not clearly described, some methodological description was missing, and test results were not described fully. Based on the manuscript, I trust the authors’ analyses and results, but I am unable to reproduce them. Further, while the authors did not use a statistical program that produces code for evaluation, there should be a way to include analyses in Microsoft Excel in supplemental material to examine how they were applied. In the submission package I received, not all analyses could be examined.
1. The authors did not describe a central hypothesis, and instead characterized the study as an exploration of growth and condition of two species. However, statistical comparisons between species and sampling sites suggest the authors evaluated potential differences. Perhaps the Introduction should explain how growth and condition could differ between species and sites. See 2 and 3 for suggestions.
2. Line 89/Figure 1. These sites are close to one another (< 5 km apart and connected). For many species, both sites could fall within a population’s geographic range. I assume individuals can move between these sites (how much are individuals of these species expected to move during the time period sampled?). Maybe it could be further described in Introduction what is different between these habitat types, and why one could anticipate differences in rock cod growth/condition between them.
3. In the Discussion, the authors attribute differences in Fulton’s K between species to morphology. I think this should be explained in the Introduction.
4. Lines 84 – 87. Two methods were used to capture fish for this study: hook and line and “fish traps.” First, more detail is needed to describe the gears used (e.g., what exactly is a fish trap?). I would be more comfortable evaluating the methods of collection if there were details of trap type, dimensions, placement in the water column, and for hook and line, e.g. how many hooks were deployed per hour.
5. Lines 86 – 87. This sentence is important, because comparisons of catch between species and sites were made later in Results. How many hours (or minutes) was each gear deployed at each site? Was there a bias for which species was captured by each gear type? Given species differences in habitat utilization, I could see conceivably that N. coriiceps would be captured more readily in a benthic trap, while N. rossii would be more readily captured by hook and line given they are described as benthopelagic. Was this evident in your collection data? If so, uneven effort between gear types could lead to bias in species capture. To this point, how would you standardize effort between gear types? Fish traps can potentially collect multiple fish at once, while hook and line may target one fish at a time (depending on number of hooks). I recognize this is a complicated question with a likely “it depends” answer, but any explanation in text would benefit reporting.
It would also be informative to comment on potential fish size biases of gear types. Were larger fish captured by hook and line? I think this is less likely to bias findings, but is perhaps necessary for characterizing methods.
At the very least, there needs to be more information about sampling effort in a supplemental file, however, I think description of effort and potential gear bias should be explained in Methods. If sample gears differ in catchability or sampling gear effort comparisons cannot be resolved, I recommend limiting conclusions about species catch differences and focusing more on length-weight relationships and condition.
6. I suggest the authors need to re-structure the Methods section to clarify statistical analyses and benefit reproducibility. In general, I found the statistical methods somewhat scattered and difficult to follow in this section. Some statistical methods were described earlier, while others are in this subsection.
I would organize the Methods with these subsections:
• Collection of fish samples
• Length-Weight Relationship
• Fulton’s Condition Factor
• Statistical Analysis
Then in the Statistical Analysis subsection, describe these comparisons in order:
• Number of individuals captured by species and site
• Comparisons of total length and weight by species and site
• LWR goodness of fit
• Fulton’s K isometric vs. allometric
• Fulton’s K by species and site
The authors could be more thorough in reporting statistical results and including supplemental files to aid in the reproducibility of their study. Conclusions could be refined to emphasize the findings of the study.
1. The supplemental data file did not include statistical analyses. A file that contains all analyses should be added to the submission. Based on Methods, this would be an Excel spreadsheet with tabs for each analysis.
2. The authors could improve their reporting of statistical tests in the Results section. When statistical results are reported, it is necessary to include corresponding test statistics for both two-way ANOVA (F, df, p) and Tukey’s post-hoc pairwise comparisons. You could add tables, report in-text, or include in supplemental material (least recommended option). Some of these statistics can be found in tables, however, not all test statistics were present, and not all statistical analyses had corresponding tables or in-text reporting.
3. Lines 251 – 252. The first two sentences of the Conclusions section are not conclusions of this study and were previously described in Introduction based on prior knowledge. Start the section with sentence 3.
4. Lines 256 – 257. Could mention that the sampling sites are close but found differences in growth and condition, suggesting potential stock structure.
5. Lines 260 – 262. This is the type of theme that I think could be more pronounced in the Introduction section.
6. Lines 264 – 265. This is the first mention of potential environmental changes. Which environmental conditions are changing in this ecosystem and how might that affect the populations’ growth and condition?
Lines 52 – 80. This is a long paragraph that could likely be split to improve readability. Further, some information, such as how LWRs are calculated, may be better suited for the Methods section.
Lines 91 – 92. While it is interesting that a penguin colony is near your sampling site, I suggest removing this sentence unless it is relevant for your comparisons. Could penguin presence inform prey availability for rock cod?
Line 137. I don’t think isometric growth can be considered positive? Potential typo
Line 167. Could compare average age (not age range) of individuals captured among sites. Maybe size difference is due to older fish being captured at Site B. Probably difficult to evaluate due to differences in number of individuals captured.
Lines 234 – 238. This paragraph is short and it would be better to either elaborate on the finding or incorporate sentences into other paragraphs.
The manuscript contains interesting information about the length-weight relationship and condition of the two dominant notothenoid species along King George Island. The amount of the material used for the analysis is sufficient and the analysis is well conducted with proper statistics.
The English language needs improvement, since many sentences are ambiguous and unclear.
The references cited in the manuscript are sufficient and cover all the discussed topics.
The Introduction chapter contains unnecessary information most of which should be moved to Materials and Methods (see comments in the text).
The results are well presented but the Discussion is somehow superficial and on some points looks unfinished. It contains many statements with well-known facts without real evidences based on the results.
The study is well designed as an experiment with sufficient material and appropriate analysis.
See comments in the text.
The study needs better representation of the results in more logic way. The discussion should be improved with more evidences from the authors data to support the statements.
Figure 6 gives information about the age distribution of both species, but this was barely commented in the text. The authors should include information about the methods used for age estimation.
The map on Figure 1 should be georeferenced.
For more comments please see the text.
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