Successful Ultrasonography-Assisted Artificial Reproduction of Critically Endangered Sichuan taimen (Hucho bleekeri)

Round 1

Reviewer 1 Report

In general one concern about this article is that it has been published as a non-peer reviewed paper at the following DOI website: https://doi.org/10.3897/arphapreprints.e85850 . This online publication was dated April 26, 2022. I would leave this up to the Fishes Editor and journal to decide whether this is duplication of work and whether or not this constitutes self-plagiarism.   There are extreme similarities (such as the figures used, for example), in both the current reviewed submission and the 2022 online publication.

There seems to be duplication of work based on online publication with different and similar authors. I would consider this a major concern that I have submitted to the editors of this journal, which is the same as the statement above. Apart from this major concern regarding duplication of reporting on same work (though each with different author names), this paper captures the contribution of ultrasonography in artificial spawning of a 'critically endangered species' and merits further attention once the journal editors and authors verify that the work is indeed not self-plagiarism and manipulation for duplication of work. Work such as this is important in the field of fisheries and aquaculture, and it would be a loss if duplication of work and self-plagiarism contributed to progress in its publication. 

Some recommendations to improve the communication paper are as follows: 

1. the choice of 'continuously' and 'monitoring' line 13 should be replaced and in-text use (e.g. line 59, should be replaced by factual statements (what was actually done, for example....'images were captured every 24 hours for a latency period of 48 to 108 h' or 'images were captured every 24 hours after artificial spawning injection starting at 0 h up to 108h'). 

2. What are optimal spawning temperature and other water quality parameters for this species? This should be clear and explicitly stated, if known, in methods, but if it was something that is unknown, it should be explicitly discussed. 

3. Change line 75 subtitle to: Ultrasound imaging procedures and evaluation. Instead of just specifying the capability range of the probe frequency (12-5 MHz) and depth settings (6 to 24 cm) specify ...be specific. What actual frequency and depth setting was used to capture images and evaluate gonadal maturity? At minimum, the settings that should be reported should include the specific frequency used, depth of ultrasound penetration, focus, and gain settings.  

4. Line 84. What was the procedure or method used to 'precisely identify maturity stages'? What were the definition of the 'stages' used? 

5. Which figure is line 134 referring to? Please put in-text Figure citation at end of that sentence.

6. Lines 139-141. Expand - explicitly state or list the decision made, the criteria used to make the decision in reference to use of ultrasound images' role in artificial collection of gametes.

7. Delete 'smoothly' in lines 147 and elsewhere that it may appear.

8. '...we developed environmental factors...' Line 169. What were environmental factors that were developed? Explain or be explicit in what these factors were.

9. Line 192. It appears that environmental factors were dependent on external hatchery water source (river environment) and not 'controlled' based on Line 196. Line 192 needs to be re-worded/re-written to clarify.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors

This paper presents an innovative methodology to improve the reproduction of Hucho bleekeri, a critically endangered freshwater fish. For this purpose, artificial spawning was performed through hormonal induction, and the progress of maturation was monitored by ultrasonography. The authors were able to apply the methodology in question, thus contributing to the adoption of an efficient tool for fish reproduction and, in this case, also for the restoration of stocks of this endangered species. 

This work is well organized and written, easy to read and understand. In general, there is little need to proceed with changes. 

Here are some more specific comments:

Abstract:

It seems to me that it is well-written and succinctly presents the work done.

Introduction:

It is well-written and easy to understand.

Just one suggestion:

Line 52-55: "These methods can increase the stress of...reproduction". It should be accompanied by a reference

Materials and methods:

It seems appropriate for the objectives of the work. I only point out the second corrections and suggestions:

Line 65: add a space on  “weight: 1.35”

Line 85: Is there a reference for the identification of the maturity stages? Or were you the first authors to use this scale? Or have you adapted a maturity ladder from another species? This should be better explained

Line 104: “ A bright light was avoided”. What does this mean? Was the hatching carried out indoors? Did you reduce the existing artificial light or natural light?

Results:

3.1.

Very interesting. No suggestions.

3.2.

Line 152: "was not significantly different". Did you make several determinations for each year and compare them statistically?

Table 1. Are the values shown averages of replicates? Or is there only one measurement/count? If the values are averages, this should be indicated, and the standard deviation of the various determinations should be shown. The value of the fertilization rate in 2013 does not seem to be correct (should be 83.50 %).

Discussion

I find the discussion interesting and well written

Line 169: “A environmental” should be “An environmental”

• Congratulations and thanks for your work

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Sichuan taimen Hucho bleekeri is a endemic, largely threatened by habitat loss and illegal fishing, and According to IUCN criteria is listed as "critically endangered” species. Therefore, it is very important to refine all stages of artificial reproduction. One of the steps proposed by the authors of the manuscript is the identification of gonadal maturity using ultrasonography.

In my opinion the aim, MM, results and discussion are written very clearly.

I have comments about:

Lines 83-85: “A few incidentally dead specimens were scanned and verified by dissection to precisely identify maturity stages (Figure 1b, c, d).”  - How many fish incidentally died? what is the percentage of fish used in the study? what does ”incidentally” mean?

These questions concern the safety of the method, which is supposed to be safe for an endangered species.

Line 106-107: “…the hatching rate was calculated after release from the membrane.” - I suggest simpler: the hatching rate was calculated on the day of hatching (when 50% of the larvae are hatched), or one day post hatching (1 dph).

Line 120 “stage III and later stage” - please describe and characterize the distinguished stages of gonadal maturity or provide the appropriate literature.

Details:

Line 71: the word “molitor” should be written in lower case.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript is improved all concerns were addressed. Thank you for your authors's response.