Adaptation Strategies to a Changing Resource Base: Case of the Gillnet Nile Perch Fishery on Lake Victoria in Uganda
, Tumi Tómasson 4, Jón Geir Pétursson 2, Anthony Taabu-Munyaho 5, Herbert Nakiyende 1 and Daði Mar Kristófersson 3Round 1
Reviewer 1 Report
Using data on fishing vessels and catch and effort, the paper considers the fishing strategies employed by motorized and paddle canoes on Lake Victoria. The paper seeks to make contributions by demonstrating that fishers adapt their fishing strategies in response to changes in the population structure and abundance of Nile Perch and seeks to classify their responses as ‘specialist’ or ‘generalist’. This subject should be of interest to readers of the journal. Unfortunately this contribution is undermined by the way that the arguments are presented, and the paper needs significant revision to address current shortcomings.
The paper presents the catch and effort data for the two sets of vessels and describes how the fishing strategies have changed over time. The paper describes these as fisher strategies and it would be interesting to know if this is the case or if it is the strategy of the boat owners. This description would benefit from being placed in context, both in terms of the changes in the stock size and structure during this period and in terms of the marketing and processing arrangements that also have important implications for the fishing strategies. The classification of the two types of vessels is as specialist and generalist is currently unconvincing. The evidence presented instead suggests that the paddle vessels have shifted to smaller mesh sizes in order to target smaller Nile perch. This is not necessarily about goals and rationalization but reflects the opportunities that are open to the two sets of fishers, and equally importantly those that are closed. The arguments presented in lines 370-376 were the most convincing. Similarly the evidence suggests that motorized vessels have also had to adapt to changes in abundance of larger fish by increasing effort as they are not able to target the more abundant smaller fish because of the size limits for the export market. This argument is made in lines 401-410. The paper would be improved if it were to just focus on this aspect of how fishers have had to adapt their strategies in response to the opportunities and constraints presented by changing resource abundance and market opportunities and constraints. This could then be discussed in relation to livelihoods and the aims of fisheries management.
There are some more specific issues with the paper that should also be addressed:
1) The title says ‘declining resource base’ yet the smaller fish were increasing so might be better to say ‘changing resource based’
2) Much of the background is concerned with the risks of overfishing and fisheries management. Yet the analysis is not necessarily about managing fisheries but about fisher strategies. It would have been useful to have a background that discusses fisher strategies and why this might be important for managers, essentially expanding on lines 90-94. The section ion Lake Victoria should include the fishing, processing and marketing as well as the management measures. Work by Fiona Nunan, Eyolf Jul-Larsen, Modesta Medard and Christophe Bėnė could all be relevant, and more use could be made of the work of Joost Beuving that the paper cites.
3) Line 39 It would be more appropriate to say that inland fisheries In Africa are largely small-scale some large-scale fisheries do exist.
4) Line 46 I am not sure that FAO requires nations to do anything.
5) Line 106 please provide scientific names for these species.
6) Line 114 please put species names in italics
7) Line 143 – missing the word method?
8) Line 166 the problems associated with the fisheries should either be elaborated on or ignored.
9) In the data analysis section the authors state that they employ the trend analysis recommended by Lorenzen (2016). This is not in the reference list and the rest of the sentence (line 187) seems out of place. More details of the trend analysis method should be provided.
10) Lines 191-195 appear to be a repetition of lines 174-179.
11) Figure 5 and 6: should be ‘triple’ and ‘quadruple’ else label ‘number of vertical gillnet panels’ and use numbers.
12) The discussion works best when relating the strategies to the market arrangements, changes in abundance and response to these two (e.g. line 415-436) and less well when attempting to classify the strategies or discussing open access fisheries.
13) Line 344 I am not sure if the distinction between the two strategies is commercial vs artisanal (in any case these terms should be defined) but about the different markets that the fish enter.
14) Line 372 which waters?
15) Line 380 suggests that it is vessel owner strategies rather than fisher strategies.
16) Lines 437-441 refer to responses to declines, yet in this case while there may be overall declines, and declines of larger fish, it appears that there remained lots of small fish.
17) Line 442 this introduces illegal fishing as an issue, and this could do with more elaboration earlier in the paper as well as a more nuanced assessment in relation to fisheries management – is fishing these small fish with a selective gear something that needs to be regulated? Especially given the implications for livelihoods. This point appears in lines 455-460 and it would be interesting to see this elaborated more.
18) Line 446-448 the reference to fish maws appears here but has not been analysed.
19) Lines 451-452 there are several authors who would disagree with this perspective
20) The conclusions section is something of a continuation of the discussion and would be improved if it were to highlight the key points about fishers’ strategies and implications for managers. Again things like the point made about open access sustainability detract from the key points.
21) Author contributions contains XX.
The paper would benefit from a thorough edit and proofread. Terminology needs to be more consistent, e.g. use of both small-scale and artisanal fisheries. In some places there are double spaces between words, different line spacing, comma delimited thousands and non-comma delimited (e.g. lines 210 and 213), incorrect wording (e.g. line 252 ‘vessels from prominently’ or line 365 ‘adoptive adaptive’). The use of numbered references is fine but when referring to what the authors did (e.g. line 349) the names should be provided. Some references cited are not in the reference list.
Author Response
Point 1: Using data on fishing vessels and catch and effort, the paper considers the fishing strategies employed by motorized and paddle canoes on Lake Victoria. The paper seeks to make contributions by demonstrating that fishers adapt their fishing strategies in response to changes in the population structure and abundance of Nile Perch and seeks to classify their responses as ‘specialist’ or ‘generalist’. This subject should be of interest to readers of the journal. Unfortunately, this contribution is undermined by the way that the arguments are presented, and the paper needs significant revision to address current shortcomings.
Response 1: Thank you for the thorough assessment of the manuscript. We agree that the most important arguments of the paper were undermined in the former submission. We have therefore revised the arguments in the introduction and discussion section, in particular, to reflect on fisher strategies as a response to population structure and abundance and also the economic factors surrounding the exploitation of Nile perch.
Point 2: The paper presents the catch and effort data for the two sets of vessels and describes how the fishing strategies have changed over time. This description would benefit from being placed in context, both in terms of the changes in the stock size and structure during this period and in terms of the marketing and processing arrangements that also have important implications for the fishing strategies.
The classification of the two types of vessels is as specialist and generalist is currently unconvincing. The evidence presented instead suggests that the paddle vessels have shifted to smaller mesh sizes in order to target smaller Nile perch. This is not necessarily about goals and rationalization but reflects the opportunities that are open to the two sets of fishers, and equally importantly those that are closed. The arguments presented in lines 370-376 were the most convincing. Similarly, the evidence suggests that motorized vessels have also had to adapt to changes in the abundance of larger fish by increasing effort as they are not able to target the more abundant smaller fish because of the size limits for the export market. This argument is made in lines 401-410. The paper would be improved if it were to just focus on this aspect of how fishers have had to adapt their strategies in response to the opportunities and constraints presented by changing resource abundance and market opportunities and constraints. This could then be discussed in relation to livelihoods and the aims of fisheries management.
Response 2: Thank you for your comment. We agree that it is important indeed to reflect if the strategies are devised for boat owners or fishers. However, we have maintained the use of fisher strategies and we elaborate on this based on the relationship of boat owners and fishing crew in the introduction lines 206-210 and also given a basis for our argument in lines 467-470. We think that decisions for strategies occur as a collective effort and also references provided indicate that boat owners on the lake are likely to be former fishers or traders thus inclusive as fishers in the study.
The classification of specialist and generalist has been excluded from the discussion, we have replaced this with the insights pointed out in your review comments. We acknowledge that fishers in the Lake Victoria setting are driven by the market opportunities available to them and Nile perch stock constraints other than being their rational choice to do so. The discussion has been refocused to elaborate on this. Thank you for the elaborate insight.
There are some more specific issues with the paper that should also be addressed:
1) The title says ‘declining resource base’ yet the smaller fish were increasing so might be better to say ‘changing resource based’
Response: Thank you for the comment, this has been changed appropriately-line 2.
2) Much of the background is concerned with the risks of overfishing and fisheries management. Yet the analysis is not necessarily about managing fisheries but about fisher strategies. It would have been useful to have a background that discusses fisher strategies and why this might be important for managers, essentially expanding on lines 90-94. The section on Lake Victoria should include the fishing, processing and marketing as well as the management measures. Work by Fiona Nunan, Eyolf Jul-Larsen, Modesta Medard and Christophe Bėnė could all be relevant, and more use could be made of the work of Joost Beuving that the paper cites.
Response: Thank you for this comment. The background section has been revised accordingly; expanding on fisher strategy and implications for fisheries management-line 72-82.
The section on Lake Victoria too has been expanded as indicated to include processing and marketing and management aspects- line 160-182, we hope this briefly gives context to the fisheries sector on the lake.
3) Line 39 It would be more appropriate to say that inland fisheries In Africa are largely small-scale some large-scale fisheries do exist.
Response: This has been changed appropriately- line 51.
4) Line 46 I am not sure that FAO requires nations to do anything.
Response: We have indicated a sentence reflecting on this issue- lines 69-70
5) Line 106 please provide scientific names for these species.
Response: Scientific names have been included- lines 158-159.
6) Line 114 please put species names in italics
Response: Species name changed to italics-line 188
7) Line 143 – missing the word method?
Response: The word is included- line 225.
8) Line 166 the problems associated with the fisheries should either be elaborated on or ignored.
Response: Sentence has been deleted- Line 243
9) In the data analysis section, the authors state that they employ the trend analysis recommended by Lorenzen (2016). This is not in the reference list and the rest of the sentence (line 187) seems out of place. More details of the trend analysis method should be provided.
Response: The reference has been indicated and the method elaborated more in lines 281-285; and 300-301.
10) Lines 191-195 appear to be a repetition of lines 174-179.
Response: Lines 191-195 deleted and sentence clarified- Lines 293-296.
11) Figure 5 and 6: should be ‘triple’ and ‘quadruple’ else label ‘number of vertical gillnet panels’ and use numbers.
Response: These have been adjusted accordingly
12) The discussion works best when relating the strategies to the market arrangements, changes in abundance and response to these two (e.g. lines 415-436) and less well when attempting to classify the strategies or discussing open-access fisheries.
Response: The discussion section has been revised, we refocused the arguments to fisher strategies as a result of Nile perch population structure and abundance; and the economic aspects governing the catches as indicated above.
13) Line 344 I am not sure if the distinction between the two strategies is commercial vs artisanal (in any case these terms should be defined) but about the different markets that the fish enter.
Response: The distinction has been elaborated as suggested, we have also provided references that give further elaboration about artisanal and commercial small-scale fisheries- lines 766-769. We acknowledge that markets too have contributed to the distinction between artisanal and commercial SSFs
14) Line 372 which waters?
Response: This has been edited, word delete and sentence elaborated.
15) Line 380 suggests that it is vessel owner strategies rather than fisher strategies.
Response: The line has been edited, nevertheless this issue was raised in point 2 above and hope that it has been addressed appropriately.
16) Lines 437-441 refer to responses to declines, yet in this case, while there may be overall declines, and declines of larger fish, it appears that there remained lots of small fish.
Response: The sentence has been deleted.
17) Line 442 this introduces illegal fishing as an issue, and this could do with more elaboration earlier in the paper as well as a more nuanced assessment in relation to fisheries management – is fishing these small fish with a selective gear something that needs to be regulated? Especially given the implications for livelihoods. This point appears in lines 455-460 and it would be interesting to see this elaborated more.
Response: We have included the illegal fishing issues in the introduction section -lines 168-172 and lines 228-230. Additionally, in the discussion we indicated the management action being undertaken for fisheries enforcement in Uganda and references attached therein- line 628-629.
18) Line 446-448 the reference to fish maws appears here but has not been analyzed.
Response: More detail on this aspect has been included. Lines 956-961.
19) Lines 451-452 there are several authors who would disagree with this perspective
Response: Thanks for the insight, however, we edited the sentence to reflect the meaning of the argument therein- lines 637-638. We argue that the existing regulation e.g., the gillnet mesh size regulation is primarily based on the biological perspective of fisheries management and this might not give the best fisheries management solution for the case of Lake Victoria which is an open-access fishery resource.
We also reflect on fisheries management on the lake in lines 688-694 in the conclusion section. However, this a good point to reflect on in future studies.
20) The conclusions section is something of a continuation of the discussion and would be improved if it were to highlight the key points about fishers’ strategies and implications for managers. Again, things like the point made about open access sustainability detract from the key points.
Response: The conclusion has been edited accordingly to reflect on the key points of the study.
21) Author contributions contains XX.
Response: This has been removed and rectified accordingly.
The paper would benefit from a thorough edit and proofread. Terminology needs to be more consistent, e.g., the use of both small-scale and artisanal fisheries. In some places there are double spaces between words, different line spacing, comma-delimited thousands and non-comma delimited (e.g., lines 210 and 213), incorrect wording (e.g., line 252 ‘vessels from prominently’ or line 365 ‘adoptive adaptive’). The use of numbered references is fine but when referring to what the authors did (e.g., line 349) the names should be provided. Some references cited are not in the reference list.
Response: The document has been proofread by a native English speaker, Inconsistences with the use of small-scale and artisanal fisheries has been checked and rectified. Consistency in the use of words has also been checked. We hope that the paper is satisfactory for the next round of the review process.
Thank you
Reviewer 2 Report
The submitted paper dwells on a very important issue, fisheries in Lake Victoria. The abstract is not cogently written. Please present briefly the findings there. All the graphs are unclear. Not readable at all. Especially Figure 9.
The literature review is not sufficient. Refer to the role of natural resources in developing countries. Differentiate between renewable and nonrenewable resources. Refer to https://www.mdpi.com/2227-7099/7/4/113
https://onlinelibrary.wiley.com/doi/abs/10.1111/rode.12716
You have to justify the employed methodology. It is not satisfactory that you just refer to Lorenzen et al., 2016 and employ the analogous methodology.
Author Response
Point 1:
The submitted paper dwells on a very important issue, fisheries in Lake Victoria. The abstract is not cogently written. Please present briefly the findings there. All the graphs are unclear. Not readable at all. Especially Figure 9.
Response 1:
Thank you for acknowledging the importance of the research to the Lake Victoria fisheries. We have revised the abstract to reflect the problem, aim of the study, key findings and conclusions. We hope that the revised version of the abstract is cogently written as expected.
We have also adjusted the graphics, specifically, font sizes and figure 9 has been edited appropriately, we hope that the current version of the paper has graphics that are clear enough and readable.
Point 2:
The literature review is not sufficient. Refer to the role of natural resources in developing countries. Differentiate between renewable and nonrenewable resources. Refer to https://www.mdpi.com/2227-7099/7/4/113.
https://onlinelibrary.wiley.com/doi/abs/10.1111/rode.12716
Response 2: Thank you for identifying the gap in the literature review. The papers recommended give a broad reflection of resource dependency and natural resource management, especially in developing countries. We have not adjusted the literature review to differentiate between renewable and nonrenewable resources, however, included https://www.mdpi.com/2227-7099/7/4/113 – line 353-354. We believe the papers recommended give a broad scope to Natural resource management and the study’s scope is limited to fisheries literature. Irrespective, we acknowledge that the narrative suits Uganda as a commodity-based economy and will consider this as an area of interest in future research.
Point 3:
You have to justify the employed methodology. It is not satisfactory that you just refer to Lorenzen et al., 2016 and employ the analogous methodology.
Response: Thank you for this insight. The methodology has been revised accordingly. We have explained in detail the methodology and justification therein- lines 281-285; and 300-301. We hope the current methodology is satisfactory as expected.
Thank you.
Reviewer 3 Report
The manuscript fits within the scope of open access journal Sustainability, but after considering all the perspectives of the submitted manuscript this MS did not manage to reach the level of this journal. First of all, I have to say that the English is so bad that the main problem for me was to understand the meaning of the written text (e.g. the authors used odd expressions - mesh size/slot size; fisheries exploitation rate/pace of fisheries exploitation..). Regarding the obtained results for me, it was quite strange that authors for a description of the catch samples used total body weight instead of total body length even though within the discussion paragraph they reflect total body length of collected specimens. I would suggest the authors to provide length-frequency distribution of target specimens for each year of investigation since it will be much easier, in the future, to convert length to age (data needed for many stock assessments) and thus enable stock assessments that will rely on scientific data. Furthermore, obtained results were more or less expected and discussed within the Discussion paragraph but this need to be shortened as authors were repeating themselves. All the references were not given in the form of numbers (Lines: 186,188, 499,500).
Finally, the authors put the effort in processing and analysing collected data but I think that they need to improve their data set and proceed the paper to some proofreading service that will check their English. Overall, I do not find this paper suitable for this journal.
Author Response
The manuscript fits within the scope of open access journal Sustainability, but after considering all the perspectives of the submitted manuscript this MS did not manage to reach the level of this journal. First of all, I have to say that the English is so bad that the main problem for me was to understand the meaning of the written text (e.g., the authors used odd expressions - mesh size/slot size; fisheries exploitation rate/pace of fisheries exploitation.).
Regarding the obtained results for me, it was quite strange that authors for a description of the catch samples used total body weight instead of total body length even though within the discussion paragraph they reflect total body length of collected specimens. I would suggest the authors to provide length-frequency distribution of target specimens for each year of investigation since it will be much easier, in the future, to convert length to age (data needed for many stock assessments) and thus enable stock assessments that will rely on scientific data. Furthermore, obtained results were more or less expected and discussed within the Discussion paragraph but this need to be shortened as authors were repeating themselves. All the references were not given in the form of numbers (Lines: 186,188, 499,500).
Finally, the authors put the effort in processing and analyzing collected data but I think that they need to improve their data set and proceed the paper to some proofreading service that will check their English. Overall, I do not find this paper suitable for this journal.
Response:
Thank you for your comments. They are indeed valuable and we have considered them for greater understanding, for this and future manuscripts. Irrespective, we had a native English speaker read through the manuscript before the second round of submission and we will appreciate it if you considered looking at the manuscript in the second stage. The inconsistencies too including the odd expressions highlighted above have been checked and clarified throughout the manuscript.
Regarding the results we acknowledge that the use of the length-frequency distribution than the total body weight of the target specimen would give appropriate scientific findings, however, we could not consider length-frequency distribution since the original data set [commercial catches] did not include the length measurements during data collection. We, therefore, found it reasonable to estimate total body weight instead of total length since the weight estimating variables, total fish specimen and total weight were recorded for this period. Irrespective, this is an issue of great concern and we hope to raise it to the necessary authorities and improve on stock assessment data collected on Lake Victoria.
We have cross-checked all the references and provided them in form of numbers accordingly and thank you again for your comments.
Round 2
Reviewer 1 Report
Thank you for the opportunity to consider the revisions to this paper. I appreciate that the authors have made a good deal of effort to refocus the paper on the strategies that fishers have adopted. However, there remain some important shortcomings. The first is in the results relating to the fishing characteristics and catch and effort data and how these relate to the adaptive strategies that are described. It is not clear what fishing is included or excluded from the analysis (e.g. dagaa and tilapia fishers) to enable the strategies to be identified. The second shortcoming is that there is not enough information regarding the changes in the stock size and structure over this period and how this related to the changes in both landings and strategies. These shortcomings need to be addressed to be able to clearly observe these strategies. In terms of the implications, lines 460-466 would benefit from clarifying that it is from the perspective of the commercial export-oriented fishery that potential benefits are squandered if fish are instead going to local markets and food chains, leading to the question raised at the end of the section.
Author Response
Point 1:
Thank you for the opportunity to consider the revisions to this paper. I appreciate that the authors have made a good deal of effort to refocus the paper on the strategies that fishers have adopted. However, there remain some important shortcomings.
The first is in the results relating to the fishing characteristics and catch and effort data and how these relate to the adaptive strategies that are described. It is not clear what fishing is included or excluded from the analysis (e.g., dagaa and tilapia fishers) to enable the strategies to be identified.
Response: Thank you for the response and for the observation made concerning the results section, we have thus included the required clarification as follows;
With the fishing characteristics [section 3.1], we introduce this as a general outlook of the vessel characteristics on Lake Victoria in Uganda, included in lines 230 and 231.
Secondly, with regards to the fishing in the analysis, we have included an additional sentence in lines 243-244 indicating the species considered for analysis i.e., the Nile perch which is also the dominantly targeted species on the lake. We hope that this is will be clear for the readers of the paper.
Point 2
The second shortcoming is that there is not enough information regarding the changes in the stock size and structure over this period and how this related to the changes in both landings and strategies. These shortcomings need to be addressed to be able to clearly observe these strategies…….
Response: Thank you for the comment, we note this as a key point thus have included biomass estimates provided in the hydroacoustic survey report 2015 in lines 461-465. In there, the estimated biomass of Nile perch increased greatly from 2007 to 2015, the increase was rather for small fish (> 95%). We hope that the explanation presented is sufficient to relate the estimated stock size and structure of Nile perch in the hydroacoustic survey to the two fishing strategies presented in the paper.
Point 3
In terms of the implications, lines 460-466 would benefit from clarifying that it is from the perspective of the commercial export-oriented fishery that potential benefits are squandered if fish are instead going to local markets and food chains, leading to the question raised at the end of the section.
Response: Thank you for this insight. This has been clarified as suggested in lines 469-470.
Reviewer 2 Report
Congrats!
Author Response
We appreciate your time and the comments earlier provided that have shaped the paper to this stage.
