Preliminary Insights on the Habitat Use and Vertical Movements of the Pelagic Stingray (Pteroplatytrygon violacea) in the Western Mediterranean Sea
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors· In abstract authors mentioned what they did but not what they found.
· Actually, the objectives established in the last paragraph of the Introduction are more concise: “The main aims of the present study were to (1) develop a new tag attachment method to avoid disruption to the ray's natural movements of the pectoral fins, (2) investigate the vertical (and horizontal) behaviour of individuals in the water column on important longline fishing grounds, as this knowledge is thought crucial to develop avoidance strategies such as deploying gear at depths or temperatures less likely to interact with unwanted species and (3) evaluate interactions with the pelagic longline fishery, including information on catch rates, at-vessel mortality (AVM) and post- release mortality (PRM).
· I do not understand why included the word “Prelimnary” in the title. Remove.
· So, I recommend to include a synthetic version of the objectives in the abstract.
· First sentence of the Materials and methods section could be: Between 2016 and 2019 in the western Mediterranean Sea, mainly in the GoL and one from Corsica Island, four different types of pop-up satellite archival transmitting tags (PSATs) from two manufacturers were deployed on pelagic stingray.
· Does the tag attachment follow any previous protocol or a combination of procedures?
· The subsection Data anlyses did not include any statistical test. Please, do include in this subsection which statistical tests were used to compare which variables.
· I am reluctant to accept a beginning sentence in the Results section with something like authors decided to use: “Detailed information on the 17 satellite tags deployed on pelagic stingray is 183 presented in Table 1.” Please, do not do that. Authors can begin mentioning key findings and then call Table 1.
· Were all these rays adults? Please, refer which is the maturation size based on fishbase.
· Why authors decided to include CPUE data in their study? They mentioned it is data from three species, but never mentioned which species (line 280). However, in Fig 7 authors say it is a stingray, blue shark and blue fin tuna. But no mentioned the species.
· In Fig. 4, how many rays are referred to? All 17? Same in Figure 5, how many? All?
· In line 409, where it reads “In this study, the AVM of 0.07%”. I recommend changing that and say, In our study….
· The Discussion must include a comparison of other investigations on ray displacement in other geographic locations of the world.
· The Conclusions section must include conclusions only and no recommendations. If authors want to include recommendations these have to be at the last paragraph of the Discussion section.
· Authors must be restricted in their comments because the work only included 17 fish and it is possible these individuals had their limitations in displacement by many reasons.
Comments on the Quality of English Language
English must be improved.
Author Response
Reviewer 1
Comment: In abstract authors mentioned what they did but not what they found Actually, the objectives established in the last paragraph of the Introduction are more concise: “The main aims of the present study were to (1) develop a new tag attachment method to avoid disruption to the ray's natural movements of the pectoral fins, (2) investigate the vertical (and horizontal) behaviour of individuals in the water column on important longline fishing grounds, as this knowledge is thought crucial to develop avoidance strategies such as deploying gear at depths or temperatures less likely to interact with unwanted species and (3) evaluate interactions with the pelagic longline fishery, including information on catch rates, at-vessel mortality (AVM) and post- release mortality (PRM). So, I recommend to include a synthetic version of the objectives in the abstract
Response: The number of words is limited to 250 in the abstract, nevertheless all the aims of the study are mentioned except item 3 (AVM and PRM), therefore we added the following sentence “At-vessel mortality was low, but there was varying evidence of post-release mortality, indicating the need for further work.”
Comment: I do not understand why included the word “Preliminary” in the title. Remove.
Response: We have retained the word preliminary in the title. Whilst this is the first study of this kind for this species and area, and adds important information on the species (and so will hopefully be published), the data are limited, which is conveyed by the use of the term ‘preliminary’ in the title (see also final comment and response for this reviewer).
Comment: First sentence of the Materials and methods section could be: “Between 2016 and 2019 in the western Mediterranean Sea, mainly in the GoL and one from Corsica Island, four different types of pop-up satellite archival transmitting tags (PSATs) from two manufacturers were deployed on pelagic stingray”.
Response: The proposed sentence has been used, but including reference to Table 1.
Comment: Does the tag attachment follow any previous protocol or a combination of procedures?
Response: The procedure is described in § 2.2. Tag Attachment and illustrated by 2 pictures, and we have also cited reference [30]. It was a protocol developed by the three authors when looking at dead specimens, and is similar to the reference cited.
Comment: The subsection Data analyses did not include any statistical test. Please, do include in this subsection which statistical tests were used to compare which variables.
Response: We do not think that such analyses are needed here, as no statistical analyses were used in this preliminary study
Comment: I am reluctant to accept a beginning sentence in the Results section with something like authors decided to use: “Detailed information on the 17 satellite tags deployed on pelagic stingray is 183 presented in Table 1.” Please, do not do that. Authors can begin mentioning key findings and then call Table 1.
Response: The sentence “Detailed information on the 17 satellite tags deployed on pelagic stingray is presented in Table 1.” has been deleted. A cross reference to Table 1 has been added at the end of the first sentence.
Comment: Were all these rays adults? Please, refer which is the maturation size based on fishbase.
Response: It is not possible to say definitively if females were mature, as their internal reproductive organs could not be examined. Nevertheless, they were likely mature (based on their size). The following sentence has been added “All the individuals tagged were likely mature, as the sizes at first sexual maturity have been estimated at about 45 cm and 34 cm disc width for females and males, respectively [33]”.
The following paper has been added to the references: Véras, D.P.; Branco, I.S.; Hazin, F.H.; Wor, C.; Tolotti, M.T. Preliminary analysis of the reproductive biology of pelagic stingray (Pteroplatytrygon violacea) in the southwestern Atlantic. Collective Volume of Scientific Papers ICCAT 2009, 64, 1755-1764.
Comment: Why authors decided to include CPUE data in their study?
Response: In 2.3. Fishery Data, we introduced the three major species caught by the fishery. The seasonal trends in CPUE have been used in conjunction with the tagging data to discuss potential movements.
Comment: They mentioned it is data from three species, but never mentioned which species (line 280). However, in Fig 7 authors say it is a stingray, blue shark and blue fin tuna. But no mentioned the species.
Response: Scientific names for the three species have been added in the legend, and the scientific names are also in the text, at the first time the species is mentioned.
Comment: In Fig. 4, how many rays are referred to? All 17?
Response: The legend to Figure 4 has been modified to “(b) a histogram showing the daily temperature ranges experienced aggregated across the six individuals”.
Comment: Same in Figure 5, how many? All?
Response: Figure 5 shows tracks of two individuals. The legend specifically states that it shows “(a) estimated path of pelagic stingray (SeaTag-3D tag 151713; 49 cm DW female that travelled an estimated 1531 km (straight-line distance 418 km) and (b) estimated path of pelagic stingray 138296 (a 54 cm DW female) tagged off the east coast of Corsica”. The inclusion of the tag number means that each track can be viewed in conjunction with the details in Table 1.
Comment: In line 409, where it reads “In this study, the AVM of 0.07%”. I recommend changing that and say, In our study….
Response: Change made.
Comment: The Discussion must include a comparison of other investigations on ray displacement in other geographic locations of the world.
Response: There are too many ‘other investigations on ray’ movements to cite in the discussion. Furthermore, pelagic stingray is somewhat unique in terms of it being the only pelagic and oceanic species of stingray. The only other published electronic tagging study for pelagic stingray is already cited and discussed, and relevant papers which have used other information sources to infer shifts in habitat use of pelagic stingray are also discussed.
Comment: The Conclusions section must include conclusions only and no recommendations. If authors want to include recommendations these have to be at the last paragraph of the Discussion section.
Response: The following sentence has been moved from the §Conclusions to the end of §4.5. Mitigation: “The use of circle hooks baited with mackerel should be investigated to determine whether catch rates of the target species are affected, as this could be a potential mitigation solution. Whilst handling time of pelagic stingray should be minimised for crew and animal welfare, the removal of hooks and trailing gear is important in maximising chances of post-release survival.”
Comment: Authors must be restricted in their comments because the work only included 17 fish and it is possible these individuals had their limitations in displacement by many reasons.
Response: We would agree entirely, hence we uses the word ‘Preliminary’ in the title (see above). We have clarified in the conclusions that “The seasonal distribution, as inferred from fishing data, are consistent with these tagging data, although more detailed analyses of movements using electronic tagging data would benefit from larger sample sizes of both sexes.”
Other amendments: In the Introduction, the reference numbers have been added for Mollet (2002)[5], Wang et al. [8], Weidner et al., 2023) replaced by [3]. We have also made a few minor edits to improve the English.
Line 55 the sentence has been modified: “The broad migration patterns of pelagic stingray have been well evidenced in some areas [5]”,
Line 59 the sentence has been modified: Mollet [5] indicated that warm waters of the eastern Pacific are utilised
Line 175 the sentence has been modified: “ bycatch data (species and number, with some data on size and sex also collected)”.
Figures
Figure 2 has been modified
Labels have the dates alongside the tag number like in figure 4a
Figure 4a has been modified
The y-axis on this plot was the wrong way around and needed to be inverted. Lower temperatures at the bottom and higher temperatures at the surface
Figure 5a has been modified
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe research on satellite tagging and release of fish aims to track and understand the migration routes, behavior patterns, and ecological requirements of fish, in order to promote sustainable development of fisheries, protect fish resources, and contribute to the conservation and restoration of aquatic ecosystems.
The paper "Preliminary Insights on the Habitat Use and Vertical Movements of Pelagic Stingray (Pteroplatytrygon violacea) in the Western Mediterranean Sea" provides an interesting and practical study. The paper thoroughly analyzes and discusses various aspects, including the introduction of Pelagic Stingray, tagging methods, data processing and analysis, habitat utilization patterns, and fisheries management and conservation strategies for this bycatch species. The author presents well-supported viewpoints.
However, the paper mentions in line 327 that "The issues of reliability extend beyond the release system, with problems also encountered with data outliers, data transfer and analysis software malfunctions." It would be valuable if the author could summarize experiences and propose improvement methods based on cases of tagging failures, as this would greatly assist similar research on satellite tagging and release of fish.
Author Response
Reviewer 2
Comment: The research on satellite tagging and release of fish aims to track and understand the migration routes, behavior patterns, and ecological requirements of fish, in order to promote sustainable development of fisheries, protect fish resources, and contribute to the conservation and restoration of aquatic ecosystems.
The paper "Preliminary Insights on the Habitat Use and Vertical Movements of Pelagic Stingray (Pteroplatytrygon violacea) in the Western Mediterranean Sea" provides an interesting and practical study. The paper thoroughly analyzes and discusses various aspects, including the introduction of Pelagic Stingray, tagging methods, data processing and analysis, habitat utilization patterns, and fisheries management and conservation strategies for this bycatch species. The author presents well-supported viewpoints.
Response: We thank the reviewer for these supportive comments.
Comment: However, the paper mentions in line 327 that "The issues of reliability extend beyond the release system, with problems also encountered with data outliers, data transfer and analysis software malfunctions." It would be valuable if the author could summarize experiences and propose improvement methods based on cases of tagging failures, as this would greatly assist similar research on satellite tagging and release of fish.
Response: It is beyond the scope of the present work (and competence of the authors) to improve the technological aspects of electronic tags. Tag manufactures and suppliers may have batches of tags that have small defects. Improved quality control of such products would certainly help, but this is clearly beyond the remit of such biological investigations. The high failure rate is a worry, and we have attempted to convey this message in a suitably nuanced way.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe reviewed article is of interest to the scientific community, the review report contains the comments and recommendations, which are attached.
Comments for author File: Comments.pdf
Author Response
Reviewer 3
Manuscript ID – animals-3056127: Preliminary insights on the habitat use and vertical movements of pelagic stingray (Pteroplatytrygon violacea) in the Western Mediterranean Sea
Comment: Abstract: It is well written and synthetically presents the scientific work on pelagic stingray which is a species that utilizes both pelagic and demersal habitats. Keywords: are sufficient and correctly reflect the content of the article. Chapter 1. The introduction is well-written. The chapter refers to the habitats preferred by the pelagic stingray (Pteroplatytrygon violacea) in the surveyed areas as well as in the natural habitats of this species and also presents the possibility of incidental capture of this species in commercial fisheries. The chapter does not require additions or additions.
Response: We thank the reviewer for these supportive comments.
Comment: Chapter 2. Materials and methods are developed in four sub-chapters as follows: 2.1. Tagging; 2.2. Tag Attachment; 2.3. Fishery Data; 2.4. Data Analysis. Materials and methods need to be reworded to make it very clear which materials are used and which methods are used. The four sub-chapters should be reworded so that the chapter responds to the title.
Response: We have made a slight amendment to the titles of the sub-chapters. We have now used 2.1 Tag Types (i.e. relates to materials), and then retained 2.2 Tag Attachment (i.e. relates to methods), 2.3 Fishery Data (relates to materials) and 2.4 Data analysis (relates to methods). We feel that this structure is the most concise approach to show the materials and methods.
Chapter 3 Results is structured in three sub-chapters as follows: 3.1. Tag Deployments; 3.2. Movements (with 3.2.1. Depth Profile; 3.2.2. Temperature Profile; 3.2.3. Horizontal Movements); 3.3. Interactions with the Longline Fishery; Sub-chapter 3.1. Tag Deployments should be redrafted in the sense that this sub-chapter contains elements that enhance Chapter 2 Material and Methods. At the same time, the sub-chapter should be completed with data from which the results are more clearly presented. The remaining part of Chapter 3 Results is relatively well written.
Response: The current structure of the results section is in line with the three aims given towards the end of the introduction, namely:
- “Develop a new tag attachment method to avoid disruption to the ray's natural movements of the pectoral fins” – this is addressed in Methods (2.2) and Results (Sub-chapter 3.1).
- “The vertical (and horizontal) behaviour of individuals in the water column on important longline fishing grounds” – this is addressed in Results sub-chapter 3.2 (Movements, with relevant subheadings).
- “Evaluate interactions with the pelagic longline fishery” – this is addressed in sub-chapter 3.3.
We understand the reviewer comments regarding where information straddles methods and results, and so have updated the initial text for Section 3.1. This now reads “A viable approach to tagging stingrays was developed (See Section 2.2), with this technique allowing for fourteen tags to be deployed on female pelagic stingray (45–60 cm DW), with the remaining three tags attached to males (39–46 cm DW; Table 1)”.
Comment: We consider it necessary that a graph relating water temperature, vertical movement of pelagic stingray (Pteroplatytrygon violacea), and bycatch in fisheries for the commercial species presented should be made in Chapter 3 Results.
Response: We are not sure that this kind of map could bring additional information in this particular study. Dedicated studies investigating CPUEs trends with explanatory variables (e.g., depth, mean depth, distance to coastline) could be conducted, nevertheless the coverage rate of the fishery is very low.
Comment: Chapter 4. Discussions are structured in five sub-chapters as follows: 4.1. Satellite Tag Deployment; 4.2. Vertical Movements; 4.3. Horizontal and Seasonal Movements; 4.4. Interactions with the Longline Fishery; 4.5. Mitigation. The chapter is well-written and does not require additions or reformulations.
Response: We thank the reviewer for these supportive comments.
Comment: Chapter 5. Conclusions is well written and does not require additions or reformulations.
Response: We thank the reviewer for these supportive comments.
Comment: References are sufficient in number and up to date, no additions are needed
Response: We thank the reviewer for these supportive comments.
Author Response File: Author Response.pdf
