Authors’ Response to Peer Reviews of “The Loch Ness Monster: If It’s Real, Could It Be an Eel?”

This is authors’ response to peer-review reports for “The Loch Ness Monster: If It’s Real, Could It Be an Eel?”

Round 1 Review

Response to Dr Don Jellyman [1]

I thank Jellyman for their polite and complimentary comments on the manuscript [2]. Because no essential revisions or other suggestions were requested by Jellyman, I have not made revisions to the manuscript in response to their review.

Response to Dr Derek W Evans [3]

I also thank Evans for their careful consideration of the manuscript.

Evans notes that “some of the data used is not quite relevant to the cold waters of Ness.” This is an important limitation. Accordingly, I have expanded the limitations paragraph of the Discussion section to read: “environmental conditions such as temperature and available biomass impact eel growth and length, therefore comparisons to other environments such as Zeeschelde may not be appropriate, i.e., some of the data cited may not be relevant to the relatively cold waters of Loch Ness.”

I apologize for causing some confusion around “Figure 2.” In the manuscript, I refer in multiple places to a “Figure 2” and a “Figure 4” that never appear in the text (eg, “Oliver et al. (2015, Figure 2)” and “Meulenbroek et al (2020, Figure 4)”). What I meant by these references were the respective figures in those publications (ie, “Figure 2 of Oliver et al (2015)” and “Figure 4 of Meulenbroek et al (2020)”). I see how my original wording was entirely confusing, and I apologize for not making this at all clear. Correspondingly, I have revised the wording of the manuscript throughout as follows: “Oliver et al (2015, Figure 2)” → Figure 2 of Oliver et al (2015)”; “Simon (2007, Figure 2(b))” → “Figure 2(b) of Simon (2007)”; “Melia et al (2006, Fig. 2)” → “Fig 2 of Melia et al (2006)”; “(Macnamara et al, 2014, Fig 2)” → “(Fig 2 of Macnamara et al, 2014)”; and “Meulenbroek et al (2020, Figure 4)” → “Figure 4 of Meulenbroek et al (2020).”

I hope that these changes to the figure references above now make it clear that I was citing figures within other published works, rather than a missing figure in my own manuscript.

Evans requested that I reference The Eel by Tesch and Thorpe [4]. In this revision, I have included additional comments with citations to three chapters of The Eel, including Kloppmann [5] (Chapter 1: Body Structure and Function, in The Eel) in the Introduction of the manuscript (third paragraph); Tesch and Thorpe [6] (Chapter 2: Developmental Stages and Distribution of the Eel Species, in The Eel) in the Discussion of the manuscript (third paragraph); and Tesch and Thorpe [7] (Chapter 3: Post-larval Ecology and Behaviour, in The Eel) in the Discussion of the manuscript (second paragraph).

Another suggestion was made to cite the work of the International Council for the Exploration of the Sea Working Group on Eels on eel biometric data, of which I note Evans is a member and so has extensive knowledge of this body of literature. To this end, I have added to the manuscript citations to the latest Report to ICES on the Eel Stock, Fishery and Other Impacts in UK, 2020-2021, from the Joint EIFAAC/ICES/GFCM Working Group on Eels (WGEEL) Country Reports 2020-2021 [8]. I use biometric data from this report to compare Mackal’s [9] eel lengths in Loch Ness to those collected elsewhere in Scotland in the same decade (Discussion, first paragraph) and to estimate ages of 1- and 6-meter eel specimens based on eel growth rates from a Scottish river (Discussion, second paragraph).

Finally, Evans requested a map of locations, which I have now provided links to in the online Supplementary Information (mentioned at the end of the Methods section), and inclusion of some images of very large 1-meter plus eels for comparative purposes, which I have now also provided links to in the online Supplementary Information (mentioned in the Discussion; because I do not own the copyrights for these images, I do not feel comfortable reproducing them directly in the manuscript).

I hope that these changes are satisfactory and that the reviewer feels that the manuscript may now be verified without reservations. I am grateful for the reviewers’ feedback, and I believe that their recommendations have greatly improved the manuscript. Accordingly, I have added Evans and Jellyman to the Acknowledgments sections of the manuscript to express my appreciation.