Human Trophic Level and Trade Openness: Insights from Global Seafood Consumption Patterns

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this study, the authors examine the relationship between Human Trophic Level (HTL) and trade openness by focusing on seafood consumption patterns. The authors use panel dataset spanning 1990 to 2019 and covering 168 countries. The empirical analyses apply fixed effects and random effects models to uncover the dynamics between trade openness, seafood diversity, and socioeconomic factors. The primary results are intuitive suggesting a significant positive correlation between trade openness and HTL, showing that increased access to diverse and high-trophic-level seafood products fosters improvements in national HTL.

Below are a few issues to be address.

1. The study uses data from Zhao et al. (2024). In fact, this study seems to be an extension of the work by Zhao et al. (2024) on the effect of trade on global aquatic food consumption patterns. However, this reference is somewhat suspicious as my internet search shows it as K. Zhao, not Y. Zhao as referenced in this paper. Also, the co-authors do not match.

2. Explain how you have arrived at Eq. (3). It seems to be a derivative of Eq. (1) or Eq. (2) in Zhao et al. (2024).

3.  Explain how trade openness from the World Bank is measured.

4. In Figure 2, explain the reason for the shift in HTL measure in late 1980s. In fact, in late 1980s’ and early 1990s’, there was a great reduction in the global trade barriers. I suggest adding a figure depicting HTL against the TO variable by geographic categories as in Figure 2. This figure could produce a visual depiction of the effect of trade openness findings in Table 4.

5. Repeated introduction of HTL acronym. On the other hand, while DC acronym is described, it is not introduced.

Author Response

Comment #l. The study uses data from Zhao et al. (2024). In fact, this study seems to be an extension of the work by Zhao et al. (2024) on the effect of trade on global aquatic food consumption patterns. However, this reference is somewhat suspicious as my internet search shows it as K. Zhao, not Y. Zhao as referenced in this paper. Also, the co-authors do not match.

• Response: As the reviewer pointed out, the typographical error in the reference has been corrected as follows:

Zhao, K.; Gaines, S.; García Molinos, J.; Zhang, M.; Xu, J.. Effect of trade on global aquatic food consumption patterns. Nat Commun 15, 1412 (2024).

Comment #2: Explain how you have arrived at Eq. (3). It seems to be a derivative of Eq. (1) or Eq. (2) in Zhao et al. (2024).

• Response: Equation (3) represents the method for calculating the human trophic level (HTL). HTL is calculated by applying weights to predetermined Trophic Level (TL) values based on the consumption quantity (Q) of each seafood item. In other words, the trophic levels of more frequently consumed seafood items have a greater influence on the final HTL value. As suggested by the reviewer, equation (3) has been modified as follows to express this more clearly.

Comment #3: Explain how trade openness from the World Bank is measured.

• Response: As the reviewer suggested, we added the following definition of trade openness (p.2):

“Trade openness is quantified as the ratio of a country's total trade volume—comprising the sum of its exports and imports of goods and services—to its GDP. This metric offers an intuitive approach to assessing the relative significance of trade in relation to a country's economic size.”

Comment #4: In Figure 2, explain the reason for the shift in HTL measure in late 1980s. In fact, in late 1980s’ and early 1990s’, there was a great reduction in the global trade barriers. I suggest adding a figure depicting HTL against the TO variable by geographic categories as in Figure 2. This figure could produce a visual depiction of the effect of trade openness findings in Table 4.

• Response: Following the reviewer’s suggestion, we have added Figure 4 (p.5), which compares trends in HTL and trade openness (TO). This addition underscores a close relationship between HTL and TO, particularly in landlocked countries.

Comment #5: Repeated introduction of HTL acronym. On the other hand, while DC acronym is described, it is not introduced.

• Response: In response to the reviewer’s suggestion, the text has been revised to provide a more explicit definition of HTL, as expressed in equation (3), along with supplementary descriptive details on page 2 (see response #2 above).

Reviewer 2 Report

Comments and Suggestions for Authors

This is an excellent and well presented paper, with a succinct Introduction, an appropriate literature review, clear enunciation of the methodology, results well illustrated with tables, and a clear discussion and conclusion.

It is suggested that the paper be supplemented by a map illustrating the three-foled classification of countries into landlocked, island and peninsula with a supporting critical paragraph of the suitability of this classification for the purposes of the paper.This would clarify the resujlts of the paper for many readers, especially those unfamiliar with the modelling approaches being used in the paper. It may also be useful to provide some more detail/definition of trade openness and human tropic level for the benefit of readers unfamiliar with exactly what these terms mean.

Author Response

Comment #l: It is suggested that the paper be supplemented by a map illustrating the three-foled classification of countries into landlocked, island and peninsula with a supporting critical paragraph of the suitability of this classification for the purposes of the paper.This would clarify the results of the paper for many readers, especially those unfamiliar with the modelling approaches being used in the paper.

• Response: As the reviewer suggested, the newly created Figure 2 on page 4 shows a map illustrating the three-fold country classification used in this study.

Comment #2: It may also be useful to provide some more detail/definition of trade openness and human tropic level for the benefit of readers unfamiliar with exactly what these terms mean.

• Response: Following the reviewer’s suggestion, we have added definitions of the human trophic level (HTL) and trade openness on page 2 as follows:

“This study investigates the relationship between trade openness and the Human Trophic Level (HTL) within the context of seafood consumption. Trade openness (TO) is quantified as the ratio of a country's total trade volume—comprising the sum of its exports and imports of goods and services—to its GDP. This metric offers an intuitive approach to assessing the relative significance of trade in relation to a country's economic size. On the other hand, HTL is calculated as the weighted average trophic level of seafood consumed in a given country, drawing on methodologies established in prior research. This measure provides valuable insights into the trophic positioning of seafood items within national consumption patterns.”

Reviewer 3 Report

Comments and Suggestions for Authors

Report of reviewing manuscript “Human Trophic Level and Trade Openness: Insights from Global Seafood Consumption Patterns”

The idea of the manuscript is very important and introduced well.

The study investigated the relationship between HTL and trade openness within the context of seafood consumption patterns.

In the present research the authors utilized a comprehensive panel dataset spanning 1990 to 2019 and covering 168 countries. The authors applied fixed effects and random effects models to uncover the dynamics between trade openness, seafood diversity, and socioeconomic factors.

The study showed that econometric models (POLS, REM and FEM) supporting trade openness promotes HTL at a national scale through the pivotal role taken by global trade networks and its impact on seafood consumption patterns.

The results revealed that geographical classification plays an important influence in HTL. In the case of landlocked countries, trade openness is the most critical factor to improve HTL to compensate for their disadvantage of not having access to marine resources. Island countries have natural geographical advantages, but their dependency on traditional fisheries may impede further improvement in HTL.

The study gives important points of view to policymakers for better development methods by which dietary improvement and environmental sustainability can take place, hence ensuring that the global seafood system is viable long into the future.

Dear authors, the text contains many editing mistakes you can find in the attached file.

Comments for author File: Comments.pdf

Author Response

Comment: Dear authors, the text contains many editing mistakes you can find in the attached file.

• Response: As the reviewer pointed out, we have corrected the identified errors to the best of our ability. Please see the revised manuscript.

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript focuses on the relationship between human trophic level and trade openness regarding the consumption of seafood. It provides new information and conclusions.

I think two basic aspects could be taken into account in order to give the study a wider interest and being less general than in the present case.

1. Although in some cases the cultivated seafood are mentioned, the study does not consider separately both kind of products, i.e., wild and farmed. The composition, and therefore, the nutritional value of both kinds of products for a single species can be very different. Also the economic value and the availability for a possible consumer.
2. Five different “regions” have been considered (Figure 1). Surely, within each of the regions, wide differences can be detected, so that the average value presented can give a too general information. My opinion is that the different regions could be separated into several ones, i.e., North-Europe/South Europe, North/Central/South America, etc. This fact will give the study a reinforced interest and more realistic information.

 

Minor aspects:

Lines 62 and 71: Perform the reference citation. Also in many other parts of the manuscript.

Conclusions: This section is normally shorter than in the present case. Maybe some aspects include now would correspond to the discussion section.

Author Response

Comment #1: Although in some cases the cultivated seafood are mentioned, the study does not consider separately both kind of products, i.e., wild and farmed. The composition, and therefore, the nutritional value of both kinds of products for a single species can be very different. Also the economic value and the availability for a possible consumer.

• Response: We utilized trophic level data from the Food and Agriculture Organization (FAO) and FishBase, consistent with prior studies. However, these data sources do not account for variations in trophic levels based on production methods, such as wild-caught versus aquaculture products, which introduces a limitation to the dataset. In the conclusion section (page 12), we addressed these data limitations as follows:

“However, several data limitations must be addressed to enhance the robustness of such analyses. For instance, existing trophic level datasets do not differentiate between production methods (e.g., wild-caught versus aquaculture), which can lead to inaccuracies in assessing sustainability and dietary impacts [40]. Additionally, only 49% of blue food is currently certified or rated for sustainability, leaving a significant portion of seafood with unknown sustainability status [41]. Certification systems themselves face challenges such as conflicts of interest, high costs, and limited criteria that fail to capture nuances like carbon footprints or small-scale producer variability. Addressing these limitations would allow policymakers and stakeholders to better develop methods by which dietary improvement and environmental sustainability can take place, ensuring  the global seafood system remains viable into the the future.”

Comment #2: Five different “regions” have been considered (Figure 1). Surely, within each of the regions, wide differences can be detected, so that the average value presented can give a too general information. My opinion is that the different regions could be separated into several ones, i.e., North-Europe/South Europe, North/Central/South America, etc. This fact will give the study a reinforced interest and more realistic information.

• Response: Following the reviewer’s suggestion, the previous continent-based regional classification was further refined into nine regions: East Asia, Latin America, MENA, Northern America, Northern Europe, Oceania, Other Asia, Southern Europe, and Sub-Saharan Africa. Accordingly, Figure 1 has been updated to illustrate the long-term trends of HTL for these detailed regions (p. 4). Additionally, the empirical results reflecting these refined regions are presented in Table 3 (pp. 9-10).

Comment #3: Lines 62 and 71: Perform the reference citation. Also in many other parts of the manuscript.

Response: In response to the reviewer’s comment, additional reference citations have been incorporated. For example:

“The role of international seafood trade in global resource distribution has been widely explored in existing literature [6,11,12,26,38]” (p.2)

“The relationship between trade liberalization and fisheries sustainability is highly dependent on governance and management frameworks [11,27,28, 39].” (p.2)

“However, several data limitations must be addressed to enhance the robustness of such analyses. For instance, existing trophic level datasets do not differentiate between production methods (e.g., wild-caught versus aquaculture), which can lead to inaccuracies in assessing sustainability and dietary impacts [40]. Additionally, only 49% of blue food is currently certified or rated for sustainability, leaving a significant portion of seafood with unknown sustainability status [41].” (p.12)

Comment #4: Conclusions: This section is normally shorter than in the present case. Maybe some aspects include now would correspond to the discussion section.

Response: As the reviewer suggested, the conclusion section has been expanded. Specifically, the policy implications of the empirical analysis results are now described in greater detail, and the significance of the regionally disaggregated empirical findings has been discussed. The data limitations of this study are also explicitly presented (pp.11-12).

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript has been performed taking into account most of the comments previously provided. I tghink it can be accepted for publication.

Author Response

Comment: The manuscript has been performed taking into account most of the comments previously provided. I think it can be accepted for publication.

Reply: Many thanks for your time and insights.