Distribution of Non-Indigenous Crayfish Species in Estonia and Their Impacts on Noble Crayfish (Astacus astacus L.) Populations

Round 1

Reviewer 1 Report

64 – The noble crayfish is primarily similar to the signal crayfish in terms of its biological demands and life cycle, including a similar appearance except for the typical white points on the claws of the signal crayfish. The morphological features of the spiny cheek crayfish are given, and here I suspect there would be confusion. Rewrite your statement.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript discusses a relevant and worrying trend of the spreading of alien crayfish in Europe. The relevance lies in the presentation of the spreading of the alien species and resulting devastation of the native species and maybe even ecosystems in Estonia and wider in Europe.

The survey period is long enough to give a clear picture of the devastating progress observed all over Europe. While similar progress of alien crayfish have been reported elsewhere, all these unfortunate trends should be reported due to their serious nature.

The manuscript presents rather basic data of rather basic research but has its merits. I have a few points for the authors to consider first with rest of my comments in the attached file (I have used several pdf-software for commenting, thus the authors have to be carefully in finding all my notes). The first matters to consider as floows:

1. The authors are using CPUE as the main variable describing their findings. It would be beneficial to reconsider how the CPUE values are being presented and discussed. Anything below CPUE 1 is just an indication of crayfish presence, thus a variation below CPUE 1 is actually not population density variation as such and should be treated as indication of crayfish presence and maybe general flaws of trapping as means of surveying (not the fault of the authors but a general feature the traps and means to catch crayfish). The CPUE values have in some cases been presented with three decimal points, which is way too accurate. The trapping as means to detect crayfish population density in this case would allow only one decimal point. I have made notes on this in the attached file.

2. The authors must always give full common names of the species they are discussing. A noble crayfish is never a 'noble' even if listed with other crayfish. It might be beneficial to use scientifc names of the species been discussed, since that is the way of science.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The authors must improve the discussion. There are paragraphs related to the plague A. astaci, but there are no results related to the detection of this organism in your methods. I included commentaries in the PDF. I wanted to read a better discussion including habitat use, feeding habits, competition, and other factors that allowed o not sympatry in nature. You have different sampling areas, use this information to discuss your findings.

 

There are missing bibliographic references in introductions and results and discussion. I included all the marks in the PDF.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has improved significantly and most of the concerns have been addressed. I still have a few comments, mainly stilistics, but also some matters that the authors should address.

In places, it is hard to follow the timeline of the species co-existence and disappearance and the authors should carefully check that the statements made regarding timelines are logical.

The software that I have been using, is, unfortunately, not fully compatible with the format of the PDF-file, for reasons unknown to me. Thus, the authors should open all comments and markings, as some of the markings have been used in a creative manner (i.e., omit-option sometimes as replace-option, with the suggested in the comment box).

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf