Pilot Passive Acoustic Monitoring in the Strait of Gibraltar: First Evidence of Iberian Orca Calls and 40 Hz Fin Whale Foraging Signals

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors, Thank you for submitting the manuscript for review. Overall, the article stands as a valid contribution as a pilot study in the documentation about the soundscape in the Gibraltar strait.

The paper presents a Figure with integrated 1s averaged PSD percentile plots that well accompany the description of the periodicity of the events visible also on the spectrogram for the entire recording duration.

Likewise, it is valuable to observe the spectrogram data about the identified killer whales´ calls and their count. However, I noticed some missing details that I would like the authors to address prior to publication.

From a methodological standpoint, the paper lacks reference to a typical characteristic of killer whale sounds, defined in some of the papers cited as "Sideband Index" SBI (Moore et al., 1988; Selbmann et al., 2023 ). I would like to ask the authors to elaborate on this concept. Since there are only 4 calls provided, it would be beneficial to understand if this has not been found at all among the samples identified.

The authors suggest that the nature of the sounds for the 40 Hz frequency should be attributed to fin whales. A behavioural reason is suggested in argumentation to the lack of such findings from other studies, but it would have been good to show a visual comparison though spectrograms or objective computed metrics showing the sound data from the authors data versus the ones reported from the references.

As proposed at the end of the paper, a constantly connected passive acoustic monitoring system would shed light on this matter.

I appreciate that the study is addressed as a Pilot study, and this is evident when reading the article. In fact, more figures showing the content of the spectrograms for the side events recorded would have been appreciated.

There are some other minor comments that should be addressed.

• Repeated paragraph "Spectrograms were computed" Page 5 line 151 and Page 6 170
• Odontocete echolocation clicks p.7, Line 222-223 at min 115. Could you provide spectrograms for these and compare to vessels? They look similar to the vertical bands of vessels from this summary plot? Or explain how the difference was deducted from data.
• Page 8 line 225: "Whale pulsed sound" There is a lot of jargon in this paper which assumes that species-specific sounds are known and identifiable to the reader. In general, since the audience of the journal might come from different fields, it would be beneficial to describe further what is intended as "whale pulsed sound" in words or other data format that help addressing this particular acoustic event. 
• Page 9 L 232.  281 other acoustics events were recorded. It is assumed that the killed whale calls were not included in these. 197 + 72 = 269 so what are the other events? It is not clear if the paragraph mentioning clicks and whistles from other species is included in this count. This paragraph would benefit from further clarification.
• Page 10 Figure 5 "Frecuency"should be Frequency. In this figure the spectrogram sound is not starting from 0s. Why?
• Page 11 line 302. Missing references [?]

Kind regards,

The reviewer

Author Response

Many thanks for the constructive and thoughtful feedback. We appreciate your recognition of the manuscript as a valuable pilot study and your helpful suggestions to improve clarity and methodological transparency.

Please find the responses in the attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript entitled "Pilot Passive Acoustic Monitoring in the Strait of Gibraltar: First Evidence of Iberian Orca Calls and 40-Hz Fin Whale Foraging Signals” describes the acoustic signals of two species of whales, particularly conforming the first register for orcas in the Gibraltar Strait. Besides, anthropophonies were characterised.  It is a well-conducted study based on recordings of 3 hours duration in total in the Strait. The study is well written and conducted; however, there are major issues to be solved before its publication. Comments were made on the manuscript; please see the annotated one. Mainly, more acoustic analysis might be conducted to characterise the four calls of the orca. Besides, the Discussion needs some work to be reorganised and summarised. Consequently, the manuscript deserves major revision.

Comments for author File: Comments.pdf

Author Response

We thank Reviewer 2 for the careful and insightful review of our manuscript. Your comments have helped us improve the clarity, precision, and methodological detail of the study. We have addressed each point raised, from clarifying terminology and strengthening the methodological descriptions, to correcting formatting and improving figure readability. In particular, we have revised the text to better define cultural behavior in cetaceans, added references where needed, and restructured the discussion to better highlight the implications of our findings. In the attached document, we provide detailed responses to each of your comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper is very interesting and shows for the first time the Iberian orcas calls. I left some few comments. In my opinion the paper is ready for publication after minor revisions. 

Comments for author File: Comments.pdf

Author Response

We sincerely thank Reviewer 3 for the constructive and detailed feedback. Your comments have helped us significantly improve the structure, clarity, and methodological transparency of the manuscript. In particular, we have reorganized key sections (e.g., Materials and Methods), clarified observational protocols, revised or removed redundant text, and adjusted figure labels and axis descriptions for consistency. We appreciate your close reading of the manuscript and your thoughtful suggestions, which have been carefully addressed point by point below.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, the revised manuscript conforms to an improved version, and it deserves publication in the present form. However, both Figures 2 and 3 still need revision since in the legend of both axes, there are grey lines or squares; please delete them.

Author Response

Dear Reviewer,

Many thanks for your review of the manuscript. We have been reviewing the two figures and we cannot appreciate lines or squares around the legends. That might be something related with the edition of the manuscript, and we remain at the disposal of the editorial office to make any necessary corrections in the formatting of the graphs if they do not have the required quality of still presenting defects.

One of the original pdf files of the graphs is attached for reference.

 

Author Response File: Author Response.pdf