The Use of a Double Bottom Trawl Set to Assess the Selectivity of Innovative Codends in Baltic Cod (Gadus morhua) Fishing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

see the attached file

Comments for author File: Comments.pdf

Comments on the Quality of English Language

some words can be improved

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

General comments:

This paper present an interesting, novel study with detailed technical descriptions of gears used and their selectivity. Outcomes of this study might be of great interest for all stakeholders involved in fishery aiming to baltic cod stocks exploitation, as well as in cod stocks preservation by decreasing fishing mortality of juveniles. This is particularly important at this moment when the International Council for the Exploration of the Seas (ICES) has advised that the TAC for cod in the Baltic Sea for 2024 should be zero for the Eastern Baltic and only 24 tonnes for the Western Baltic Sea. Authors can discuss about this issue in the paper also (protection of juveniles, stock recovery,...) in relation to possible gains with inovative codends use.

Materials and Methods section is very detailed (sometimes even too detailed) from technical point of view, but there is nothing about statictical analyses/tests of the results obtained. Please add.

Considering the fact that cod is a highly important fish species in the Baltic Sea, both environmentally and commercially, and that some novel technical solutions described in this paper are potentially useful in other world fisheries too, I would reccomend this paper for publication in Fishes, but only after major revision in line with reviewer's comments.

 

Specific comments:

Line 2 – add scientific name of the species in the title

Line 25-26 – please add description of the term „structure“ (age, length, weight, sex?)

Line 27-28 – this sentence is more appropriate for Acknowledgment or Funding than for Introduction; please move and remove it from reference listopad;

Lines 75-82 – it would be better to move this paragraph to Discussion section;

Lines 83-87 – move this paragraph in Materials and Methods section and a more detailed Table to present clearly detailed info on experimental hauls can be added, perhaps as a supplement (if too large);

At the end of Introduction, add a paragraph with clear description of the purpose / aim of this study, hypotheses, etc.

Lines 91-97 – it is nice to see photos of those fishing vessels, but these Figs 1-3 do not contribute to overall findings of this paper and could be removed or combined in one single Figure; Table 1 describe very well the characteristics of the vessels used in this study;

Figure 4 caption (Line 128) and all other captions need to be sufficiently explanatory – figures with its captions/text need to be fully understandable, without the need to look for some explanations in the paper – this is a general comment (not for Fig 4 only)

Line 149 – please add info on fishing depth also for a such trawl setting, corresponding to 300 warps length;

Line 158-159 – it is unclear how it was measured!? With acoustic devices such as SCANMAR or similar?

Line 168 – add info on trawling speed also

Line 170 – Quality of Figure 8 must e improved; from part a) it is not clear which part corresponds to ICES area 27.3.d.26 and from part b) the codes of fishing squares are not visible and it remained unclear what blue dots on the map represent?

Lines 173 vs. 175 – please note that weight and mass are not synonymous; different units are used for mass and weight; with devices showed in the paper you measured weight, not mass; if you want to change from weight to mass divide values in N by gravity (9.8 m/s^2); if the measuring devices were calibrated in mass units (g, kg), please add info about this;

Line 350 - it is unclear if the % of undersized fish is related to number or weight of fish!?

Lines 351-366 – results presented in different figures are difficult to follow, because of different scales on vertical axes between figures; it is suggested to present detailed numerical results in Table(s) and to remove Figures 16-23; make clear comparisons in selectivity between 3 different codend tested (UC, UC+JD+JK and UC+DD+DK) against T90 and herring codends and statistically test significance of differences observed.

Line 372 – Discussions and conclusions – this section have to be more elaborated, including comparisons with other studies mentioned in Introduction; also, as authors well noted, amounts of undersized cods in the catch is depending on the length structure of Baltic cod population in the sea, and it might be influenced by fishing in different seasons, or... Conclusions should be clear and based on significant results of this study.

Line 375 – authors stated that UC codend „significantly“ reduces the number..., but there were no statistical tests that confirms significant differences between codends; lack of statistical analyses is one important shortcoming of this paper! Please apply appropriate statistical tests in order to test differences between different codends.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The improvements to the text are providing more interest and the graphs are much better now. The additional details are very useful, even if additional comments about the possible running costs of the new methodology should have been useful.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

While I thank the authors for their effort in replying to some of the comments and improving the manuscript, but I was disappointed to see that some impotrant comments I made were largely unaddressed in the manuscript. Below are the pasted comments from my previous review that are still relevant.

Previous unaddressed comments:

1) At the end of Introduction, add a paragraph with clear description of the purpose / aim of this study, hypotheses – such paragraph, indicating clear objective of the study and hypotheses to be tested is still missing at the end of Introduction. The text added in lines 65-76 mentioned by authors, do not explain the aim/objective of study nor hypotheses (comparison of different cod-ends, differences testing,…)

2) figures with its captions/text need to be fully understandable, without the need to look for some explanations in the paper – not considered

3) Line 158-159 – it is unclear how it was measured!? With acoustic devices such as SCANMAR or similar? – text added in the manuscript (rescaled from model testbed in the lake) is not clarifying the issue for article’s readers

4) Line 170 – Quality of Figure 8 must e improved; from part a) it is not clear which part corresponds to ICES area 27.3.d.26 and from part b) the codes of fishing squares are not visible and it remained unclear what blue dots on the map represent? – changes made by authors did not resolve the issues mentioned, but additionally complicate it; now it seems from part c) that hauls were made in coastal area only!?

5) Lines 351-366 – results presented in different figures are difficult to follow, because of different scales on vertical axes between figures; it is suggested to present detailed numerical results in Table(s) and to remove Figures 16-23; make clear comparisons in selectivity between 3 different codend tested (UC, UC+JD+JK and UC+DD+DK) against T90 and herring codends and statistically test significance of differences observed. – not considered

6) lack of statistical analyses is one important shortcoming of this paper! Please apply appropriate statistical tests in order to test differences between different codends. – Material and method section is still missing a clear description of statistical methods/test used to process the results obtained, significance of differences observed between different cod-ends has not been statistically tested; this is a critical issue! Authors also missed to explain conversion they made from weight to mass in this section.

Therefore, in my opinion the manuscript needs further development and improvement, particularly in statistical significance testing of differences observed. Lack of clear hypotheses made in line with paper clear objective and their testing prevented authors to make a clear conclusions also.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf