Relationship between the Spatial and Temporal Distribution of Squid-Jigging Vessels Operations and Marine Environment in the North Pacific Ocean
Round 1
Reviewer 1 Report
Dear authors, thank you for this effort in reframing the manuscript and addressing my previous comments. This new version of the manuscript reads better, and the analysis's objective is more precise: i.e. “to evaluate the spatial distribution of fishing vessel operation and its relationship with the marine environment”.
The authors used fishing effort reconstructions from Global Fishing Watch binned monthly on a 0.5x0.5 grid and linked this effort with 4 environmental drivers as well as lon/lat. The results presented are redundant with previous analysis. The authors mainly reproduce observations previously described from the study of logbooks. It is shown by the discussion that reads a lot as an evaluation of the results of this manuscript. To reach a broader audience, it would be preferable that the authors moved beyond reproducing results.
For example, the authors have high resolution (daily/0.1degree) observation of the dynamic of fishing effort with AIS data. It would have been helpful to look more closely at the variability of this effort at distinct temporal scales, or compare seasonal fishing effort between years, or discuss inter-annual differences in the gravity center of monthly fishing effort. Multiple references link the distribution of squid in the North East Pacific to the environment, the novelty here being that the authors use AIS instead of logbooks. It would have been helpful to demonstrate the added value of using AIS for this study.
Here are a few specific comments in response to the authors :
- Regarding the spatio-temporal scales: Indeed, most analyses adopt binning at a monthly scale, and Gong et al. indicate that the optimal temporal and spatial scales with the lowest CV are month and 0.5x0.5. But these results are based on a comparison of a categorical index with SST only, from the authors themselves, “each variable (meaning environmental factors) may have its own optimal scale”. Exploring the sensitivity to spatio-temporal scale might have added content to the manuscript.
- Regarding the lat/lon: Indeed, it is common to use lon/lat as predictors, but environmental drivers strongly correlate with latitude in your domain. To investigate the impact of the environment on squid-jigging vessel operations, it could be useful to assess how the environment alone captures the effort variability. Testing a model where lon and lat are removed could add content to the manuscript.
Finally, while reviewing I found few recent references addressing a similar topic as the present manuscript that could be referenced:
Wang, W., Zhou, C., Shao, Q. and Mulla, D.J., 2010. Remote sensing of sea surface temperature and chlorophyll-a: implications for squid fisheries in the north-west Pacific Ocean. International Journal of Remote Sensing, 31(17-18), pp.4515-4530.
Wang, J., Cheng, Y., Lu, H.J., Chen, X., Lin, L. and Zhang, J., Water temperature at different depths affect the distribution of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean. Frontiers in Marine Science, p.2094.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear author/authors,
It is my pleasure to review the manuscript (MS) with the title of “Relationship between the spatial and temporal distribution of squid-jigging vessels operations and Marine environment in the North Pacific Ocean”. In general, the manuscript contains original and valuable research information. The manuscript is well written and organized, obtaining relevant results that can be applied for fishing pressure on marine resources to improve the knowledge about the fishing operations of fishing vessels. However, are some scientific lacking (see details comments and suggestions in manuscript file).
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The present MS contains very important research on the exploitation of natural resources. The work is well written as it stands. In my opinion, it requires minor revision. My detailed comments are contained in the text. To see them all, open the file in Acrobat Reader.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Thank you for sending me this paper to revise; below I outline my general comments regarding the quality of the manuscript
The manuscript investigates the spatial distribution of squid-jigging vessels using AIS data in the Pacific Ocean and their relationship with the marine environments. While I think the results are of sound and represent a good contribution to the use of remote sensing for identifying fishing activity and the associated environments it deserves to be crafted further to be ready for publication. Introduction and discussions need to be further improved. For a reader that does not know the study area and the fleet dynamics of the species, it is difficult to follow the work. It is not clear for the readers which are the major knowledge gaps in the squid-jigging fishery and the main contribution of this study. The paper is insufficient knowledge of literature. My suggestion is that the article requires a major revision in order to be acceptable for publication
Introduction:
Need to be improved. The subject of the article is not thoroughly reviewed and there is a lack of discussion of the basic references. It is not clear for the readers which are the previous studies focused on the area and the species and which are the major knowledge gaps in this fishery is not clear..for example... publications in line 30 cite “the relation between the spatial distribution of this species......” but the references followed are not focused on the study of O.bartramii. Which are the novel results found in this study in relation to that found in Fan et al Zhu et al Thian et al??. Include a new paragraph based o AIS and VMS studies including relevant references. Some of the references are recommended.
Li et al., 2021 Assessment of environmental stress caused by maritime vessels based on a comprehensive model using AIS data: A case study of the Bohai Sea;van der Reijden et al., 2018 North Sea demersal fisheries prefer specific benthic habitats among others; Sala-Coromina, Joan, et al. "European hake (Merluccius Merluccius, Linnaeus 1758) spillover analysis using VMS and landings data in a no-take zone in the northern Catalan coast (NW Mediterranean)." Fisheries Research 237 (2021): 105870.
Material and methods:
Please include a study area section including the main oceanographic characteristics and the zones cited in the Discussion section (ie. Kuroshio)
Line 76-79: Please explain the database from which the Vessel data in this study came. Also include the methodology used to filter the squid-jigging ship type from the other AIS signal.-
Results
Figure 8. Why not limit the ranges value of Chl 0-1
Discussion
Needs to rewrite in some parts, the authors repeat detailed results that can be found in the Results section (including the specific figure numbers that don’t need). What was the most important result of the study? Please in each paragraph concisely summarize the major result(s) and then describe how the results fit with existing literature. Some examples..
79-Why the fishing effort is concentrated in September?? which may be the main drivers of these results?
Line 303-328 Example lines 303-328 describe the main results found by other authors but without fitting with the results found.
Conclusion
It is not a conclusion paragraph it off just a future studies paragraph, please clarify. What is the main contribution the study makes to the field?
Reviewer 2 Report
This manuscript presents a method to estimate squid fishing effort in the North Pacific from AIS signals over the fishing season from July through November. Once this fishing effort is computed and averaged monthly on a 0.5 x 0.5 grid, the authors compare the distribution of effort with 3 environmental variables, SSH, SST, and Chla. They use the comparison to infer the link between reconstructed effort and environment.
The introduction clearly states the importance of understanding the link of exploited species with their environment. The idea of using fishing observation to assess fish distribution indirectly is worth exploring. But I feel the authors are falling short in demonstrating their objective of “verifying the feasibility of applying fishing vessel trajectory data to the spatial distribution of fishery resources”. Furthermore, the manuscript lacks a clear conclusion and mostly suggests ranges of optimum environmental conditions where fishing occurs. But as far as I understand, these ranges echo the ranges estimated from CPUE presented in other papers, CPUE being a better indicator for evaluating this range.
Following are several general points that would require clarification:
- Where are the AIS data coming from? There are no details about these data besides an acknowledgment of Global Fishing Watch (GFW).
- Since the authors know GFW, why not use the GFW effort reconstructions to study squid fisheries? As far as I know, these reconstructions are based on machine learning methods that might be more accurate than the method presented here. These could be useful to either compare with the effort estimates of the authors and test the precision of the authors' estimations, or used directly to analyze the link between fishing effort and environment? Please clarify.
- It is unclear at what temporal scale the effort estimations are compared with the environment. Is it 15 (3 years x 5 months) monthly maps of effort compared with monthly maps of the environment? Why not use a higher temporal resolution (MODIS provides down to daily SST, Chl, there are also SSH products down to 5 days resolution)? The authors use fine temporal scale fishing observation (derived from AIS); this allows comparing with fine scale environmental data. If I misunderstood, please clarify, or justify why monthly maps are more relevant to address the main objective (i.e. “applying fishing vessel trajectory data to the spatial distribution of fishery resources”).
- Regarding the GAM models, why do the authors use the coordinates lat/lon? If the intent is to link fishing effort to the environment, using only the 3 environmental drivers appears more relevant. If the objective is to have geographical data to include technical limitations on fishing activity, distance to port or the nearest coast might be more appropriate. My point here is that environmental drivers correlate with lat/lon (especially lat) over the domain, so using them as a predictor might weaken the identified link between environment and effort. Please clarify.
In my opinion, the paper's intent and its conclusions must be clarified/strengthened. Addressing the previous points in a subsequent version would contribute to it.
Here are a few additional specific comments:
- L88 and in the method, I feel the word “brightness” is confusing. Squid jigging vessels use light projectors to attract the squids, but it refers to day/night here as I understand. So please clarify, maybe prefer “solar angle” to “brightness”.
- Eq. 1, what are V1 and V2, 0 and 15 knots?
- L116-117, please clarify why “some trajectory points” are deleted.
- Fig.3 , the label seems misplaced.
- L283, typo, ”are mainly mainly consists”
- L321-328: “Young et al. … during the day and night”. I don’t understand why this sentence appears here where the discussion is about the diel vertical migration of squids. Then I don’t understand the link with SSH “Thus, SSH is also an environmental factor…”. Please clarify.
