Assessing the Technical and Economic Viability of Galvanizing Snow Crab (Chionoecetes opilio) Traps

Round 1

Reviewer 1 Report

The authors assess the CPUE of snow crabs using old ungalvanized, new ungalvanized and new galvanized traps. They determine that there is no difference in catch between new ungalvanized versus new galvanized traps, and both perform better than the old traps. They analyze the catch data using a Generalized Linear Mixed-effects Model (GLMM) equation and statistical measures to determine significant differences. They conclude that there is no significant difference between either type of new traps, but they are less clear if the statistical differences between old and new traps are significant because confidence intervals overlap.

They then investigate the cost over time of ungalvanized traps that have a lifespan of three years versus galvanized traps that are expected to last 21 years. They assess the various trap costs under different scenarios of inflation and discount rates using three equations. This analysis was fairly complicated economics and difficult for me to understand, but someone knowledgeable about economics might not find it so.

They determine that in most cases it is economically favorable to galvanize the traps.

This would seem to be a fairly straightforward investigation, but I feel that the extensive data analysis and economics modelling makes it more confusing and the conclusions less clear than need be. I would prefer to see the various statistical and economics discussions relegated to an Appendix and just the summary points presented in the Results and Discussion, but others may want to see the actual analyses.

Several figures are unnecessary and could be dropped. Figure 2 diagrams the galvanization process but it is adequately explained in the Introduction, so the diagram is not needed. Figure 3 is a map showing the study area but the investigation is not site-specific so there is no need to show where the traps were deployed. Figure 4 shows an enlarged section of a trap with dimensions but it is irrelevant to the investigation results. Figure 7 graphically shows the cost analysis in 4 scenarios; this information is presented in the text so this figure could be dropped; if it is retained as more visually instructive, interpretations for each scenario would be helpful.

The paper is well-written, although tedious to get through all of the statistical analyses and economics models. The use of the English language is fine.

The number of references (41) seems reasonable, but I do not know if any are redundant so could be eliminated or if any relevant sources have been omitted. Reference #11 is a Personal Communication – does the journal want this listed as a Reference?

I think that this information could be useful to snow crab fishers but I’m not sure how wide the interest would be outside of that industry The paper is appropriate for publication in Fishes, but I would like to see revisions to tighten up the data analysis and conclusions so it is easier to understand the findings, especially if the target audience is fishers rather than scientific researchers or economists.

Additional specific line by line comments for authors:

Line 12 – what is “mild carbon steel”?

Line 60 – to maintain symmetry in the phrases, change to “…6) allowing the flux solution to dry; …”

Line 64 – place semicolon after (ZnO)

Figure 3 – not needed but if kept, the axis labels do not need to include “(decimal degrees)” because only whole degrees, no decimal values, are included

Lines 88-91 and Figure 4 (not needed) – this information about traps should be in the Introduction

Lines 103-104 – sentence “This was obtained…frames.” Can be deleted

Lines 113-114 – I’m curious why no female crabs were captured. Can you explain this?

Lines 119-130 – I find this information to be tedious, but it can be kept if you feel it is necessary. Could it be moved to an Appendix?

Line 132– you can’t just refer to other work with the reference number. You need to say something like “…similar to other life cycle cost analyses [29-33].”

Line 134 – I am not an expert in economics, so I don’t understand what is meant by “discounted into current dollars” and “discounted rates” mentioned elsewhere. Can you briefly explain what this means?

Lines 141-142 – You have already made this statement re personal communication in lines 44-45 and you repeat it again in lines 218-219 as well as list it as Reference #11. Why not just cite it as “[11]” if you are going to include it in the list of References?

Lines 131-157 – Again, as in lines 119-130, I find this to be excessive and it detracts from the story being told. Can you summarize, move to Appendix, etc. so the reader does not have to wade through all this analysis?

Lines 159-168 – I am concerned that you removed several traps from the analysis when you are comparing CPUE’s for different traps. Perhaps the fact that the same number of each trap type was removed makes it OK? You should address this potential problem.

Figure 5 – This figure is fine when seen in color but if it is printed in black and white the different trap type bars are indistinguishable. Can you make them different fills – one solid and 2 different types of crosshatching for example?

Lines 178-183 – Types and reasons for statistical analysis should be in Methods

Lines 185-188 – It would be interesting to know what CPUE’s you would get with “old galvanized traps”. Any plans to compare them to the other traps when they get older? You might want to mention this as a possible future study.

Lines 201-202 – Are the differences between old traps and either new trap types significant or not? You say the CI’s overlap but you don’t say if they a significantly different.

Lines 223-230 – I find this section confusing. Can you explain it for someone who is not an economist (which presumably would include your target audience of crab fishers).

Lines 241-245 – This information about attractiveness of shinier traps is interesting but you could present it in a clearer way.

Lines 255-258 – same comment as for lines 223-230

Figure 7 – I don’t understand what is meant by “Discount Rate”. For readers such as myself, perhaps you could add some explanation for each graph, eg. “At 0% inflation (A) a galvanized trap is more economical when the discount rate is …” etc.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

General comments

This paper tries to evaluate the technical and economic viability of galvanizing snow crab traps by measuring the CPUE during the commercial fishery and assessing the economic viability by evaluating the life cycle cost over a range of inflation and discount rates.

The objective of the manuscript, in general, is interesting from a fisheries and economic point of view. However, the study needs some improvements to reach the standard of publication. The manuscript should become acceptable for publication pending suitable minor revision considering the comments appended below.

More specific comments:

Title and Keywords: reflect the content of the paper. However, the Abstract needs to be rewritten to reflect the content of the paper following the same paper sequence (introduction, objective of the paper, material and methods, main results, and conclusions). For example, the material and methods used, and discussion or conclusion are missing. Please check.

Introduction:

Please add some information about the fishery in the area (e.g., number of vessels, fishers, employment creation, economic importance of snow crab compared to other fishery resources etc.) to justify the importance of the fishery and therefore of the study.

Material and methods:

Line 95 – 96: " Three different trap treatments were evaluated: 1) new galvanized crab traps, 2) new 95 traditional crab traps, and 3) older traditional crab traps.". Please add an additional table comparing the main characteristics of the 3 types of traps.

Line 108 – 110: "A fleet of 50 traps (16 old, 16 new, and 18 galvanized) was used for the first haul and a fleet of 77 traps (27 old, 25 new and 25 galvanized) was used for the remaining hauls.". Why was a balanced number of traps for each type not used? Is there any reason for this structure of traps? Please clarify.

Line 113 – 114: " No female snow crabs were captured as part of this experiment.". Please clarify that this was not allowed due to management regulations.

Results:

Line 175 – 177: "The observed mean CPUE was 34.4 (±15.8 standard error of the mean (SEM)) for old traps compared with 39.5 (±14.5 SEM) for new traps and 39.4 (±13.9 SEM) for galvanized traps (Figure 5).". Please add the units (e.g., crab per trap). Check the whole manuscript.

Line 181 – 184: "The model with the lowest Second Order Akaike Information Criterion (AICc) score was…". Please add to material and methods that the AIC was used to evaluate how well a model fits the data it was generated from, by comparing different possible models and determining which one is the best fit for the data.

Discussion and conclusion:

The section provides a good summary and explanation of the results in the light of other studies. However, the discussion is too short, and I think it would benefit from comparing with other similar studies in other regions, or by providing recommendations to the fishery managers to support the fishery.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

This paper evaluates the economic feasibility of increasing durability through the application of galvanizing technology to snow crab traps. I believe that this paper will be used as important data in the operation of the snow crab trap fishery.

 I offer the following opinions about this paper and believe that it needs to be revised.

This paper needs to be revised with reference to the review comments below.

Opinion 1;

It is believed that this paper was used for economic analysis by conducting sea trials and using catch data.

However, it is believed that the number of tests in fishing trials is small.

In addition, it is judged necessary to present long-term test results and data in order to suggest that the galvanized fish traps presented by the author in this paper are economical due to increased durability and reduced replacement and maintenance costs.

  In this regard, the author must add data and considerations that can clearly assert that the results are reasonable.

Opinion 2;

In snow crab trap fishing, the frame of the trap has little effect on the catch, and generally the effect on the catch is the material of the trap net, the size of the mesh, the shape of the trap, and the shape of the entrance.

Therefore, it can be generally assumed that there is no significant difference in CPUE between new traps and galvanized traps. In addition, the low catch of old traps is not due to the frame of the trap, but rather to various external factors such as the age of the net and interference with bait attraction by creatures and seaweed living in nets

In this respect, the difference between the three types of catches is a result that can be inferred, and it is judged that there is a lack of sea test data that can more clearly prove these results.

Opinion 3;

Because it can be expected that the durability of snow crab pots will increase if the frame is galvanized, an economic analysis of the maintenance and replacement costs of the crab pots should be comprehensively conducted during economic analysis. In particular, the durability of the trap frame increases, but at the same time, the durability of the net decreases, so it is judged necessary to add data or comprehensively consider the cost of net maintenance.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have addressed all of my comments. They have not agreed with all of them but have provided justification for their decisions. I am satisfied.

Note -- there is a typo in line 273 -- "shiner" should be "shinier"

Reviewer 3 Report

I believe that the author has sincerely revised this text in accordance with the opinions expressed.

I think there are some differences of opinion in terms of evaluating fishing gear performance, but I accept the answers and corrections provided by the author.

I look forward to more diverse research results from the author in the future.