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Cited by 2Marine and fisheries researchFish Ecology and Management StudiesAquaculture Nutrition and Growth

Impacts of phytoplankton availability on bigeye tuna (Thunnus obesus) recruitment in the Indian Ocean

Open access
Wang, Yang, Zhang, Yuying, Geng, Zhe, Zhu, Jiangfeng·2024·Frontiers in Marine Science
DOI 10.3389/fmars.2024.1392273
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Abstract

A sustainable fishery relies on consistent and substantial recruitment. There is, however, considerably high mortality among fish larvae during their early development. One of the most important factors determining larval survival is foraging success. Bigeye tuna is among the most important commercial species in the Indian Ocean. Despite being routinely researched and assessed, it remains unclear how food availability affects the recruitment success of bigeye tuna.In this study, we used phytoplankton size (MD50) as an indicator of prey availability and investigated the connection between MD50 and bigeye tuna recruitment from 2000 to 2018 through the Beverton-Holt stock-recruitment function. The Indian Ocean was divided into four regions to accommodate spatial differences. As a result, larger MD50 could bring higher recruitment, particularly in the eastern and southern Indian Ocean. Based on the analysis, we inferred that for bigeye tuna, the eastern Indian Ocean is the primary spawning ground, and the peak spawning period falls in Season 2 (April-June). The conclusions provide valuable insights for understanding the recruitment characteristics of bigeye tuna in the Indian Ocean.

AI snapshot

Written from the paper’s full text.

TL;DR

This study uses median phytoplankton size (MD50) as a proxy for larval food availability and links it to bigeye tuna recruitment in the Indian Ocean via the Beverton–Holt stock–recruitment function. It finds that larger MD50 is associated with lower density-independent mortality (β) and therefore higher recruitment, supporting the “critical period” hypothesis.

Key findings

  • MD50 was negatively related to β, implying that larger phytoplankton size (more food for zooplankton prey) corresponds to lower mortality and higher bigeye tuna recruitment.
  • In all-season model 1, significant negative relationships occurred in R1S (p = 0.003, r = -0.333), R2 (p < 0.001, r = -0.371), and R3 (p < 0.001, r = -0.546), but not in R1N (p = 0.152, r = -0.166).
  • After excluding anomalous seasons, model 2 correlations strengthened and were significant in all regions (p < 0.001): r = -0.544 in R1N, -0.561 in R1S, -0.665 in R2, and -0.677 in R3; adjusted r² values were 0.28, 0.31, 0.43, and 0.45, respectively.
  • The authors infer that the eastern Indian Ocean is the primary spawning ground and that peak spawning occurs in Season 2 (April–June).

Methods

  • The Indian Ocean was divided into four regions based on the bigeye tuna stock assessment: south-western equatorial (R1S), north-western equatorial (R1N), eastern equatorial (R2), and southern (R3).
  • MD50 was derived from satellite chlorophyll-a and sea surface temperature data for 2000–2018; β was back-calculated from the Beverton–Holt stock–recruitment function using seasonal spawning biomass and recruitment from the IOTC Stock Synthesis assessment (1975–2018).
  • Linear regression and Pearson correlation were used on Z-transformed MD50 and β, with two models: one using all seasons and one excluding anomalous seasons (R1N excluding season 2, R1S excluding season 3, R2 excluding season 2, R3 excluding season 2); residual diagnostics were shown as Q–Q plots.

Limitations

  • The paper states that stock assessment data cannot be shared due to permission restrictions, and that recruitment estimates from tuna stock assessments carry considerable uncertainty, including assumptions of constant growth, selectivity, and natural mortality, process and observation errors, and controversial settings for steepness and σR.
  • The paper states that the model’s arbitrary seasonal time step may not accurately reflect complex spawning behavior, that inaccuracies in growth function estimation may bias recruitment timing, and that egg quality of Indian Ocean bigeye tuna is poorly verified; previous spawning-season estimates are inconsistent with this study’s findings.
  • Evident from the text: the analysis period is limited to 2000–2018 because continuous chlorophyll-a records before 2000 were limited; time-lag effects were disregarded; and excluding anomalous seasons in model 2 may remove biologically meaningful variability.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3389/fmars.2024.1392273

Cites

43 of 47 references verified0 citation errors · 4 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

22 of 67 cited sources checked · 10 supported · 1 flagged · accuracy not yet measured

  • Premisecitation
    § Discussion

    The 'critical period' hypothesis was also borne out in the study of Woodworth-Jefcoats and Wren (2020).

    “The “critical period” hypothesis was also borne out in the study of Woodworth-Jefcoats and Wren (2020).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Woodworth-Jefcoats and Wren, 2020 source

      The Results report significant correlations between phytoplankton size four years earlier and bigeye tuna catch rates in Hawaii’s longline fishery. The Discussion links this finding to the hypothesis that food availability during early life affects survival, but the study did not directly measure survival during that critical period. The finding is consistent with the hypothesis rather than a direct demonstration of it. (LLM, conf=0.83)

      Experimental — accuracy not yet measured
  • Premisecitation
    § Introduction

    For bigeye tuna, which primarily spawn in tropical regions, prey availability is more relevant than temperature to larvae.

    “In particular, for species such as bigeye tuna, which primarily spawn in tropical regions, prey availability is more relevant than temperature to larvae (Reglero et al., 2014; Shropshire et al., 2022).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites Reglero et al., 2014 source

      The Results place predicted bigeye larval occurrence in equatorial waters and find that both temperature and eddy kinetic energy significantly predict its occurrence (page not available in our copy). The ocean triad hypothesis section suggests that local food enrichment may help tuna larvae survive, but does not establish that prey availability matters more than temperature for bigeye larvae. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites Shropshire et al., 2022 source

      The Results (Habitat suitability; page unavailable) say declining prey biomass increased food limitation for Atlantic bluefin tuna larvae, while increased temperature had an approximately neutral effect on food limitation. This supports the prey-versus-temperature comparison for the species studied, but the paper does not establish it for bigeye tuna or describe bigeye spawning regions. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation
    § Introduction

    Tuna larvae depend on zooplankton availability after yolk sack absorption.

    “To meet their metabolic requirements, tuna larvae hinge on the zooplankton availability after the yolk sack absorption (Llopiz and Hobday, 2015; Shropshire et al., 2022).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Llopiz and Hobday, 2015 source
    • cites Shropshire et al., 2022 source
  • Premisecitation
    § Introduction

    The median phytoplankton size (MD50) is a proxy for larval food quality.

    “The median phytoplankton size (MD50) was used as a proxy for the larval food quality (Barnes et al., 2011).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Barnes et al., 2011 source

      The Methods section defines a phytoplankton cell-mass measure at which 50% of total biomass is reached, supporting the median-size component of the claim. The Discussion links phytoplankton size to food-chain structure, but the paper does not identify median size as a proxy for larval food quality. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Findingown data
    § Discussion

    Recruitment is higher during seasons 2 and 3.

    “Recruitment is higher during seasons 2 and 3.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.
  • Classified as probably not a substantial claim. 42
  • May combine two claims. 29

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation
    § Methods

    In the Beverton-Holt function, α is mainly linked to density-dependent mortality rates, whereas β pertains to mortality caused by external (density-independent) factors such as temperature, wind, currents, and food availability.

    “The parameters α and β are related to two types of mortality: α is mainly linked to density-dependent mortality rates, whereas β pertains to the mortality caused by external (or density-independent) factors, such as temperature, wind, currents, and food availability (Beverton and Holt, 1957; Miller and Brooks, 2021).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Beverton and Holt, 1957

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Miller and Brooks, 2021 source

      Section 2 assigns the mortality relationships in the opposite direction: the Beverton–Holt term governing recruitment at zero spawning biomass depends on density-independent mortality, while the second term includes density-dependent mortality and also depends on the first. The paper does not give temperature, wind, currents, or food availability as examples of factors governing β in this passage. Page numbers are unavailable in our copy. (LLM, conf=0.90)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    In Woodworth-Jefcoats and Wren (2020), MD50 was identified as an environmental driver of bigeye tuna recruitment and can be an informative predictor of bigeye tuna catch rates in Hawaii's deep-set longline fishery with a 4-year forecast window.

    “In their study, MD50 was identified as an environmental driver of bigeye tuna recruitment and can be an informative predictor of bigeye tuna catch rates in Hawaii’s deep-set longline fishery with a 4-year forecast window, aligning with the results of our study.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Woodworth-Jefcoats and Wren, 2020 source

  • Classified as probably not a substantial claim.

    Premisecitation
    § Introduction

    The feeding success of larvae is one of the most important processes in their survival.

    “The feeding success of larvae is one of the most important processes in their survival (Anderson, 1988; Llopiz and Hobday, 2015).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Anderson, 1988 source
    • cites Llopiz and Hobday, 2015 source

  • May combine two claims.

    Premisecitation
    § Introduction

    Tuna larvae have a very narrow diet and are highly selective in consuming limited species of zooplankton in the shallow mixed layer.

    “They have a very narrow diet and are highly selective in their consumption of limited species of zooplankton inhabiting the shallow mixed layer (such as appendicularians, cladocerans, and cyclopoid copepods in the genera Farranula and Corycaeus) (Llopiz and Hobday, 2015; Artetxe-Arrate et al., 2021).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Llopiz and Hobday, 2015 source
    • cites Artetxe-Arrate et al., 2021 source

      Section 3.2, p. 9 states that larvae and small juveniles eat planktonic organisms in the shallow mixed layer. It does not say that larvae have a very narrow diet, are highly selective, or consume only a limited set of zooplankton species; it does not name the taxa in the citing sentence. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    The importance of food availability on recruitment is also found in other marine fishes, e.g., Pomacentrus amboinensis, Sardina pilchardus, and North Sea cod.

    “The importance of food availability on recruitment is also found in other marine fishes, e.g., Pomacentrus amboinensis (Jones, 1986), Sardina pilchardus (Guisande et al., 2001), and North Sea cod (Olsen et al., 2011).”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites Jones, 1986 source
    • cites Guisande et al., 2001 source
    • cites Olsen et al., 2011 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Introduction

    The period after endogenous yolk feeding and first exogenous feeding has been hypothesized as a 'critical period' that determines recruitment success, but the hypothesis remains controversial.

    “This period has been hypothesized as a “critical period” (Hjort, 1914) that determines recruitment success, but the hypothesis remains controversial (Sifa and Mathias, 1987; Robert et al., 2013).”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites Hjort, 1914

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Sifa and Mathias, 1987 source
    • cites Robert et al., 2013 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Introduction

    Bigeye tuna eggs hatch into larvae about 3 mm in length in a few days, develop foraging and swimming organs quickly, and grow into juveniles within the first month of life.

    “Eggs laid typically hatch into larvae (about 3 mm in length) in a few days, develop foraging and swimming organs quickly, and then grow into juveniles within the first month of life (Miyashita et al., 2001; Reglero et al., 2014).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Miyashita et al., 2001

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Reglero et al., 2014 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    The lipid composition of fish eggs improves due to the alteration of habitat that adults are exposed to during the spawning seasons.

    “Some researchers have shown that the lipid composition of egg improved due to the alteration of habitat that adults are exposed to during the spawning seasons (Navas et al., 1997; Yanes-Roca et al., 2009).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Navas et al., 1997 source

      The Abstract and Discussion (page numbers unavailable) report that broodstock diet affected egg fatty acid composition and that higher fatty acid ratios were associated with better egg quality. They do not study habitat alteration during spawning; the Lipid class composition of the eggs section also reports no significant differences in lipid classes between diet groups. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
    • cites Yanes-Roca et al., 2009 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    The eastern Indian Ocean (R2) serves as the principal spawning area, and the temperate region (R3) functions as the feeding grounds for bigeye tuna.

    “It is generally believed that the eastern Indian Ocean (R2) serves as the principal spawning area, and the temperate region (R3) functions as the feeding grounds for bigeye tuna (Reglero et al., 2014; Muhling et al., 2017; Fu, 2019).”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites Reglero et al., 2014 source

      The Results (page unavailable) place bigeye tuna larvae throughout the tropics in every ocean, which supports spawning in the Indian Ocean but not the eastern Indian Ocean as its principal spawning area. The paper does not identify a temperate region as bigeye tuna feeding grounds; its statement about larvae in the tropical East Indian Ocean concerns southern bluefin tuna. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites Muhling et al., 2017 source
    • cites Fu, 2019

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation
    § Methods

    The Beverton-Holt stock-recruitment function describes the relationship between recruit abundance and spawning biomass of the stock.

    “The B–H stock–recruitment function describes the relationship between the recruit abundance and the spawning biomass of the stock (Miller and Brooks, 2021).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Miller and Brooks, 2021 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Introduction

    Bigeye tuna recruits experience exceedingly high mortality throughout the hatching and early life stages.

    “It is worth noting that the recruits experience exceedingly high mortality throughout the hatching and early life stages (Anderson, 1988; Russo et al., 2022; Shropshire et al., 2022).”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites Anderson, 1988 source

      The Size dependent mortality section says mortality generally decreases as marine fish grow, and Present Understanding Starvation reports very high mortality among first-feeding larvae of some species. The paper does not establish that bigeye tuna specifically experience exceedingly high mortality throughout hatching and early life stages. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites Russo et al., 2022 source

      The Introduction says tuna eggs and larvae have high mortality, and the Discussion calls early life the period with the highest mortality rates (pages unavailable). But the paper's three studied species are Atlantic bluefin, bullet, and albacore tuna, not bigeye tuna; it does not establish the claim specifically for bigeye recruits. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites Shropshire et al., 2022 source

      The Introduction says broadcast-spawning fish such as Atlantic bluefin tuna experience exceedingly high mortality upon hatching and throughout early life. The Results section, “Temporal variability in larval survival,” also reports very low early survival for Atlantic bluefin tuna. The paper does not establish this specifically for bigeye tuna recruits. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    The mid-Atlantic cold pool was an important predictor of yellowtail flounder recruitment, but projections were less than ideal due to uncertainty in the projected cold pool.

    “Although the results suggest that the cold pool was an important predictor of recruitment, the projections were less than ideal due to the uncertainty associated with the projected cold pool.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Miller et al. (2016) source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    Miller et al. (2016) proposed a state-space approach treating environmental covariates as stochastic processes and estimated the effects of environment variables on southern New England yellowtail flounder recruitment.

    “Miller et al. (2016) proposed a state-space approach that treats environmental covariates (the mid-Atlantic cold pool) as stochastic processes and estimated the effects of the environment variables on southern New England yellowtail flounder (Limanda ferruginea) recruitment.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Miller et al. (2016) source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    High-quality eggs generally lead to higher hatching rates, improving recruitment success.

    “Consequently, high-quality eggs generally lead to higher hatching rates, improving the recruitment success (Kjørsvik et al., 2003; Ienaga et al., 2021).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Kjørsvik et al., 2003 source
    • cites Ienaga et al., 2021 source

      The Introduction (page unavailable) says low-quality eggs generally have poor hatching success and produce larvae with lower growth and survival, supporting the claim about egg quality and hatching. It links egg quality to efficient hatchery seed production, but does not establish an improvement in recruitment success. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data
    § Results

    In model 2 after removal of the anomalous season, β and MD50 had significant correlations (p < 0.001) in all regions, with correlation coefficients -0.544 in R1N, -0.561 in R1S, -0.665 in R2, and -0.677 in R3.

    “Upon the removal of the anomalous season, model 2 exhibited enhanced correlations. β and MD50 had significant correlations (p < 0.001) in all regions, with correlation coefficients being -0.544 in R1N, -0.561 in R1S, -0.665 in R2, and -0.677 in R3, respectively.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Findingreasoning
    § Discussion

    The highest values of correlation coefficients were discovered in R3, closely followed by R2.

    “Accordingly, the highest values of correlation coefficients were discovered in the R3 and closely followed by R2.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Findingown data
    § Results

    In model 1 using all-season data, MD50 showed significant negative linear relationships with β in regions R1S (p = 0.003, r = -0.333), R2 (p < 0.001, r = -0.371), and R3 (p < 0.001, r = -0.546), but no significant correlation in region R1N (p = 0.152, r = -0.166).

    “According to model 1, MD50 showed significant negative linear relationships with β in regions R1S (p = 0.003, r = -0.333), R2 (p < 0.001, r = -0.371), and R3 (p < 0.001, r = -0.546). However, no significant correlation was found in region R1N (p = 0.152, r = -0.166).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Findingown data
    § Results

    The majority of MD50 is negatively related to β as hypothesized, although there are some outliers.

    “According to Figure 2, the majority of MD50 is negatively related to β as hypothesized, although there are some outliers.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Findingown data
    § Results

    In regions R1N, R2, and R3, outliers predominantly occurred in season 2 (April-June); in region R1S, outliers were primarily attributed to season 3 (July-September).

    “In the regions R1N, R2, and R3, outliers predominantly occurred in season 2 (April–June). In the region R1S, outliers were primarily attributed to season 3 (July–September).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Findingown data
    § Discussion

    Recruitment is lower during seasons 1 and 4 and corresponds to the lower MD50 in all regions.

    “The recruitment is lower during seasons 1 and 4 and corresponds to the lower MD50 in all regions.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • Classified as probably not a substantial claim.

    Premisenone given
    § Abstract

    It remains unclear how food availability affects the recruitment success of bigeye tuna.

    “Despite being routinely researched and assessed, it remains unclear how food availability affects the recruitment success of bigeye tuna.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Langley et al., 2009 source
    • cites Zhu et al., 2010 source
    • cites Muhling et al., 2018 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Introduction

    The precise timing and location of bigeye tuna recruitment in the Indian Ocean remain uncertain.

    “Although bigeye tuna has been regularly assessed in the Indian Ocean, the precise timing and location of recruitment are still uncertain (Fu, 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Fu, 2019

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given
    § Discussion

    R3 is located in the temperate Indian Ocean where the temperature is presumably cooler for bigeye tuna spawning or larval survival.

    “and R3 is located in the temperate Indian Ocean where the temperature is presumably cooler for bigeye tuna spawning or larval survival.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    Accurately accounting for population structure in stock assessments can improve model performance and reduce bias.

    “Accurately accounting for population structure in stock assessments can improve model performance and reduce bias (Punt, 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Punt, 2019 source

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given
    § Introduction

    High mortality rate often follows the strictly endogenous yolk feeding period as well as the first exogenous feeding phase.

    “High mortality rate often follows the strictly endogenous yolk feeding period as well as the first exogenous feeding phase.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Introduction

    Bigeye tuna spawning exhibits both seasonal and year-round characteristics.

    “The spawning of bigeye tuna exhibits both seasonal and year-round characteristics (Muhling et al., 2017).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Muhling et al., 2017 source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationreasoning
    § Discussion

    The high correlation coefficient in R3 could be ascribed to increased metabolic demands in lower-temperature environments.

    “The high correlation coefficient in R3 could be ascribed to the increased metabolic demands in lower-temperature environments.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Interpretationreasoning
    § Discussion

    In addition to temperature reported by literature, food availability also strongly influences recruitment success.

    “The results of this study indicate that, in addition to temperature reported by literature, food availability also strongly influences recruitment success.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given
    § Introduction

    A higher MD50 signifies larger phytoplankton and, in turn, more food available for the zooplankton upon which larval bigeye tuna feed.

    “A higher MD50 signifies larger phytoplankton and, in turn, more food available for the zooplankton upon which larval bigeye tuna feed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Discussion

    Despite insufficient food supply, numerous eggs may also contribute to higher recruitment.

    “Despite the insufficient food supply, numerous eggs may also contribute to higher recruitment.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § Discussion

    The 'critical period' hypothesis posits that the survival rate of newly hatched larvae is highly sensitive to feeding conditions during the first feeding stage.

    “which posits that the survival rate of newly hatched larvae is highly sensitive to feeding conditions during the first feeding stage (Hjort, 1914).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hjort, 1914

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Discussion

    Based on the previous hypothesis that more food could bring more recruitment, season 2 with opposite trends may be anticipated to be the spawning season.

    “Based on the previous hypothesis that more food could bring more recruitment, season 2 with opposite trends may be anticipated to be the spawning season.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • May combine two claims.

    Interpretationown data
    § Discussion

    Food availability plays a crucial role in bigeye tuna recruitment, thereby supporting the 'critical period' hypothesis.

    “The results highlight that food availability plays a crucial role in bigeye tuna recruitment, thereby supporting the hypothesis of the “critical period”, which posits that the survival rate of newly hatched larvae is highly sensitive to feeding conditions during the first feeding stage (Hjort, 1914).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hjort, 1914

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • The authors state this as an assumption: β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationown data
    § Discussion

    This heterogeneity emphasized the importance of spatially structured stock assessment.

    “This heterogeneity emphasized the importance of spatially structured stock assessment.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Introduction

    Only a limited amount of research has explored the influence of larval foraging success on bigeye tuna recruitment, with most information on tuna recruitment and reproduction confined to the Pacific Ocean.

    “Thus, only a limited amount of research has been conducted to explore the influence of larval foraging success on the recruitment of bigeye tuna, with most information being related to tuna recruitment and reproduction confined to the Pacific Ocean (Langley et al., 2009; Zhu et al., 2010; Muhling et al., 2018; Woodworth-Jefcoats and Wren, 2020).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Langley et al., 2009 source
    • cites Zhu et al., 2010 source
    • cites Muhling et al., 2018 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Introduction

    Bigeye tuna spawning occurs in tropical and sub-tropical waters when surface water temperature exceeds 24°C.

    “It occurs in tropical and sub-tropical waters when the surface water temperature exceeds 24°C (Nishikawa and Kenkyūjo, 1985; Schaefer, 2001).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Nishikawa and Kenkyūjo, 1985

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Schaefer, 2001 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    A higher lipid composition of fish eggs enhances their survival and development by providing energy reserves, essential fatty acids for structural integrity, and resilience against environmental stressors.

    “A higher lipid composition of fish eggs enhances their survival and development by providing energy reserves, essential fatty acids for structural integrity, and resilience against environmental stressors (Singh et al., 2021).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Singh et al., 2021 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    Bigeye tuna spawn in the western Indian Ocean between January and April and in the eastern Indian Ocean from December to January and in June.

    “previous studies have demonstrated that bigeye tuna spawn in the western Indian Ocean between January and April and in the eastern Indian Ocean from December to January and in June (Nootmorn, 2004; Zudaire et al., 2022)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Nootmorn, 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Zudaire et al., 2022

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning
    § Conclusion

    Larger MD50 could bring lower mortality and therefore higher recruitment.

    “MD50 was negatively related to β, suggesting that larger MD50 could bring lower mortality and therefore higher recruitment.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Langley et al. (2009) developed a generalized linear model to predict variation in yellowfin tuna recruitment across the western and central Pacific Ocean in relation to environmental variables.

    “Langley et al. (2009) developed a generalized linear model (GLM) to predict the variation in yellowfin tuna (Thunnus albacares) recruitment across the western and central Pacific Ocean in relation to a multitude of environmental variables.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Langley et al. (2009) source

  • May combine two claims.

    Premisecitation
    § Discussion

    Both the additive-error and survey-index methods of including environmental covariates generated relatively high-quality estimates.

    “Both methods generated relatively high-quality estimates, either by including environmental covariates as an additional component of the S–R function or by fitting covariates in the model as a survey index of recruits outside the S–R function.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Galindo-Cortes et al. (2010) source
    • cites Crone et al. (2019) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Recruitment exhibits considerable temporal variation because egg production and subsequent larval survival are highly sensitive to biotic and abiotic factors.

    “recruitment exhibits considerable temporal variations owing to the egg production and the subsequent larvae survival being highly sensitive to both biotic and abiotic factors (Maunder and Thorson, 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Maunder and Thorson, 2019 source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Study design and conductnone given
    § Discussion

    The model time step is arbitrarily divided and may lack the flexibility to accurately reflect complex spawning behavior in nature.

    “Given that the model time step is arbitrarily divided, it may lack the flexibility to accurately reflect the complex spawning behavior in nature.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationown data
    § Conclusion

    It is important to incorporate environmental oceanographic variables, such as those related to pre-recruit feeding, into recruitment estimates in the stock assessment of bigeye tuna in the Indian Ocean.

    “This research strongly suggests the importance of incorporating environmental oceanographic variables, such as those related to pre-recruit feeding, into recruitment estimates in the stock assessment of bigeye tuna in the Indian Ocean.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Integrating recent GLM recruitment indices into stock assessment may enhance the precision of estimates of current and projected biomass and exploitation.

    “They reported that integrating the recent GLM recruitment indices into stock assessment may enhance the precision of estimates of the current and projected (in the next 1 to 2 years) biomass and exploitation.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Langley et al. (2009) source

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationcitation
    § Discussion

    These methods could potentially pave the way for incorporating chl-a data into the bigeye tuna S-R function.

    “These methods could potentially pave the way for incorporating chl-a data into the bigeye tuna S–R function.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Fishery-independent recruitment monitoring programs remain rare in tuna management due to high cost and logistical challenges.

    “due to the high cost and logistical challenges, they remain rare in tuna management (Kolody et al., 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kolody et al., 2019 source

  • Classified as probably not a substantial claim.

    Premisecitation
    § Discussion

    Environmentally informed recruitment forecasting would be more successful for species whose population dynamics are dominated by recruitment and where recruitment is driven by strong environmental factors.

    “Haltuch et al. (2019) suggested that environmentally informed recruitment forecasting would be more successful for species whose population dynamics are dominated by recruitment and where recruitment is driven by strong environmental factors.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Haltuch et al. (2019) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Galindo-Cortes et al. (2010) explored the effect of environmental variables on the Pacific sardine stock-recruitment relationship by incorporating these variables into the S-R function as additive random errors.

    “Galindo-Cortes et al. (2010) explored the effect of environmental variables on the Pacific sardine (Sardinops sagax) stock–recruitment (S–R) relationship by incorporating these variables into the S–R function as the additive random errors.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Galindo-Cortes et al. (2010) source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Discussion

    The recruitment variability parameter σR is frequently overestimated and there is controversy regarding the setting of σR in tuna stock assessments.

    “Several studies have pointed out that σR is frequently overestimated, and there are still controversies regarding the setting of σR in tuna stock assessments (ISSF, 2011; Kolody et al., 2019).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites ISSF, 2011

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Kolody et al., 2019 source

  • Classified as probably not a substantial claim.

    Premisecitation
    § Discussion

    Crone et al. (2019) proposed including environmental information in integrated stock assessments to inform S-R dynamics.

    “Crone et al. (2019) proposed including environmental information in the integrated stock assessments to inform the S–R dynamics.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Crone et al. (2019) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    The marginal likelihood approach possesses superior statistical properties compared to the penalized likelihood approach.

    “researchers have found that, compared to the penalized likelihood approach, the marginal likelihood approach possesses superior statistical properties (Maunder and Deriso, 2003; Valpine and Hilborn, 2005).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Maunder and Deriso, 2003 source
    • cites Valpine and Hilborn, 2005 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Discussion

    If there are inaccuracies in the growth function estimation, the recruitment timing may be biased.

    “if there are inaccuracies in the growth function estimation, the recruitment timing may also be biased.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § Discussion

    Growth, selectivity, and natural mortality are typically assumed to be constant over time in stock assessments.

    “While growth, selectivity, and natural mortality are typically assumed to be constant over time in stock assessments”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Maunder and Thorson, 2019 source
54 of 54

  • The authors state this as an assumption.

    β is a vector of random effects whose seasonal values can be back-calculated from observed seasonal spawning stock biomass and recruitment time series.

    “Assuming that β is a vector of random effects, its seasonal values can be back-calculated according to the observed Sy and Ry time series (Equation 4).”

  • The paper relies on this without support.

    Very limited studies have verified the egg quality of bigeye tuna in the Indian Ocean.

    “However, very limited studies verified the egg quality of bigeye tuna in the Indian Ocean, more efforts still need to be conducted.”
2 of 2

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • All-region significance claim conflicts with the R1N result

    Minor

    The paper says β and MD50 have significant opposite trends in all regions, including comparisons using the original data. It later reports that their correlation in R1N is not significant for those data (p = 0.152).

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 12

  1. Fu, 2019, Preliminary Indian Ocean Bigeye Tuna Stock Assessment 1950-2018 (Stock Synthesis)
  2. Huang, 2017, NOAA Extended Reconstructed Sea Surface Temperature (ERSST), Version 5
  3. 2011, Report of the 2011 ISSF Stock Assessment Workshop Rome, Italy, March14-17, 2011, ISSF Technical Report 2011-02
  4. 2022, Status of the world fisheries for tuna. Nov. 2022, ISSF Technical Report 2022-15
  5. Lowe, 1839, A Supplement to “A Synopsis of the Fishes of Madeira”: Communicated May 1839
  6. Mace, 1988, A Generalised Bioeconomic Simulation Model for Fish Population Dynamics
  7. Miyashita, 2001, Morphological development and growth of laboratory-reared larval and juvenile Thunnus thynnus (Pisces: Scombridae), Fish Bull, 99, 601
  8. 2018, MODIS-TERRA Level 3 Mapped Chlorophyll Data Version R2018.0
  9. Nishikawa, 1985, Average distribution of larvae of oceanic species of Scombroid fishes 1956-1981
  10. Secretariat, 2022, Review of Indian Ocean bigeye tuna statistical data Indian Ocean Tuna Commission
  11. Vincent, 2018, Incorporation of updated growth information within the 2017 WCPO bigeye stock assessment grid and examination of the sensitivity of estimates to alternative model spatial structures
  12. Zudaire, 2022, Preliminary estimates of sex ratio, spawning season, batch fecundity and length at maturity for Indian Ocean bigeye tuna

Cited by

Sorted by citations

Related

Authors
Wang, Y., Zhang, Y., Geng, Z., & Zhu, J.
Affiliations
  • Shanghai Ocean University (CN)
  • Florida International University (US)
  • Ministry of Agriculture and Rural Affairs (CN)
Corresponding author
Zhu, Jiangfeng
Venue
Frontiers in Marine Science
Publisher
Frontiers Media SA
Published
2024-07-19
Volume
11
ISSN
2296-7745 (ISSN-L)
DOI
10.3389/fmars.2024.1392273
OpenAlex
W4400838433
Cited by
2
References
46
Citations by year
2025: 2
FWCI
0.36
Type
journal article
Language
en
Open access
Licence
Locations
  • Frontiers in Marine Science (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
Topics
  • Physical Sciences › Environmental Science › Global and Planetary Change › Marine and fisheries research
  • Physical Sciences › Environmental Science › Nature and Landscape Conservation › Fish Ecology and Management Studies
  • Life Sciences › Agricultural and Biological Sciences › Aquatic Science › Aquaculture Nutrition and Growth
Keywords
bigeye tuna, larval recruitment, phytoplankton cell size, prey availability, foraging success, spawning grounds, spawning season, larval mortality, Indian Ocean

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-16.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-16.

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