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Cited by 106Marine and fisheries researchFish Ecology and Management StudiesOceanographic and Atmospheric Processes

Worldwide distributions of tuna larvae: revisiting hypotheses on environmental requirements for spawning habitats

Open access
Reglero, P, Tittensor, DP, Álvarez-Berastegui, D, Aparicio-González, A, Worm, B·2014·Marine Ecology Progress Series
DOI 10.3354/meps10666
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Abstract

Tuna are among the most ubiquitous oceanic predators, and range globally from the equator to temperate regions (0 to 55° latitude).While the distribution of adult fish has been mapped from fishing records, the extent of tuna spawning and larval habitats is less well understood.We compiled and analyzed data on the global distributions of larval occurrence for 7 major oceanic tuna species to investigate environmental predictors of larval habitat.Our results showed that tuna larvae occur within the adults' distributional range, but were restricted to lower latitudes and higher water temperatures than adults, largely consistent with Schaefer's 'temperature hypothesis'.Temperature requirements explained much of the variation in larval occurrence, though temperature by itself tended to over-predict the extent of larval habitats.We also demonstrate that tuna larvae have an elevated probability of occurrence at intermediate values of eddy kinetic energy, generally supporting Bakun's 'ocean triad hypothesis', which relates tuna larval habitats to mesoscale oceanographic activity.However, some deviations in this pattern were also observed, such as for albacore.Regions of suitable larval habitats were most commonly found in western boundary currents, where warm water masses coincide with intermediate eddy kinetic energy.Bluefin tuna species are exceptional though, in that their spawning habitats tended to be much more confined than predicted from oceanographic conditions.Our results provide support for a combination of the 2 hypotheses to explain global environmental requirements for tuna larvae.We have identified oceanographic parameters that can easily be measured by remote sensing and features that should be considered when determining areas of critical habitat for tuna larvae.

AI snapshot

Written from the paper’s full text.

TL;DR

This study compiled global larval occurrence records for 7 tuna species and modeled presence/absence against sea-surface temperature (SST) and eddy kinetic energy (EKE). It found support for a combination of the temperature and ocean triad hypotheses, with larvae restricted to warmer, lower-latitude waters than adults and generally peaking at intermediate EKE, except for bluefin tunas and albacore.

Key findings

  • Tuna larvae occupied a much narrower range than adults: generally 30°S–30°N, except Mediterranean larvae above 35°N, whereas adults ranged from 60°S to 60°N. Larvae preferred warmer waters, with maximum temperature tolerances ≥28.5°C for all species; minima were <22°C for skipjack, yellowfin, albacore, bigeye and Pacific bluefin, but >24°C for Atlantic and southern bluefin. Maximum larval occurrence probabilities were mostly at SSTs of 27.4–27.8°C, except Atlantic bluefin (26.5°C) and Pacific bluefin (25.3°C).
  • Temperature was positively related to larval occurrence in all species analyzed, with a lower tolerance around 20°C, lower than Schaefer’s 24°C spawning boundary; however, temperature alone over-predicted plausible larval habitats for all species, especially bluefin tunas.
  • EKE effects varied: skipjack, yellowfin and bigeye larvae had highest occurrence at intermediate EKE of 0.01–0.06 m² s⁻²; Atlantic bluefin showed a linear positive relationship; albacore showed a negative linear relationship; southern bluefin EKE was not significant. Model deviance explained was 39.6% for skipjack, 38.9% for yellowfin, 32% for bigeye and 29.3% for albacore.
  • Suitable larval habitats were most common in western boundary currents where warm water masses coincide with intermediate EKE; bluefin tuna spawning habitats were much more spatially confined than predicted from oceanographic conditions.

Methods

  • The authors reviewed scientific and grey literature on tuna larval surveys, retaining 150 articles, of which 92 reported georeferenced tuna larval catches. They mapped presence/absence for 7 oceanic tuna species in 1678 5° × 5° grid cells between 70°S and 70°N, excluding land; absence data came from geo-referenced absences in targeted cruises and historical ichthyoplankton surveys.
  • Seasonal SST from satellite remote sensing and EKE calculated from satellite-altimetry-derived geostrophic velocity components were averaged to 5° cells. Larval presence/absence was modeled with binomial generalized additive models (GAMs) using smoothing splines for SST and EKE, with an area term added for wide-ranging species; stepwise backwards selection chose best models.
  • Larval temperature tolerances were estimated from probability density histograms of observed occurrences by SST; adult temperature tolerances were taken from Boyce et al. (2008). Adult ranges for comparison came from Worm & Tittensor (2011).

Limitations

  • Stated in the paper: the combined database had good spatial coverage but individual surveys were spatially and temporally fragmented, not internationally coordinated, and often covered only restricted areas within main spawning grounds; presence-absence data provide occurrence but not relative abundance or density; larval species identification from morphology can be problematic, especially in the Gulf of Mexico; sampling years ranged from the 1920s to the 2000s; EKE values were missing for the Mediterranean, so no predictions were obtained there; bigeye tuna data are few and interpretations should be cautious.
  • Evident from the text: the GAMs are correlative and cannot establish the mechanisms linking SST/EKE to larval survival; EKE is used as a proxy for mesoscale activity and frontal density; the 5° grid may miss smaller-scale or topographically induced mesoscale structures in confined seas; adult range comparisons rely on contemporary ranges from Worm & Tittensor (2011), which may not match the temporal coverage of larval surveys.

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

Integrity signals

Registry

Crossref · 10.3354/meps10666

Cites

84 of 84 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

13 of 56 cited sources checked · 6 supported · 0 flagged · accuracy not yet measured

  • Interpretationown data

    The results support the ocean triad hypothesis.

    “This supports the ocean triad hypothesis (Bakun 2006).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Bakun 2006 source
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.
  • Premisecitation

    Growth rates of tuna increase with temperature.

    “Regarding favorable temperatures for growth, the compilation of data from different tuna species suggests increasing growth rates with temperature (Reglero et al. 2011), but further studies are needed at the species level.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Reglero et al. 2011 source

      The “Maximum specific growth rate” section reports that specific growth rates of Pacific bluefin tuna larvae increased with temperature, and the “Mortality effect of size-surfing cannibalism” section likewise describes faster larval growth in warmer water. The cited paper supports the temperature–growth relationship for larvae, but the cited passage does not establish it from a compilation of growth data across different tuna species. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
  • Study design and conductcitation

    Surveys often covered restricted areas within the limits of the main spawning areas, a common issue in icthyoplankton surveys.

    “Surveys often covered restricted areas within the limits of the main spawning areas, a common issue in icthyoplankton surveys (Bernal et al. 2007).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Bernal et al. 2007 source
  • Findingcitation

    Physiological temperature limits for gonad development and egg development obtained from experiments matched the spatially observed larval temperature tolerance limits well.

    “Physiological temperature limits for biological processes such as gonad development and egg development obtained from experiments (Sawada et al. 2005, Margulies et al. 2007, Masuma et al. 2008) matched the spatially observed larval temperature tolerance limits well.”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Sawada et al. 2005 source

      The spawning and rearing sections report temperatures at which Pacific bluefin tuna spawned and larvae were raised in captivity. They do not establish physiological temperature limits for gonad or egg development, or compare those temperatures with spatially observed larval tolerance limits. The indexed passages provide section labels but no specific page numbers. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
    • cites Margulies et al. 2007

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

    • cites Masuma et al. 2008 source
  • Premisecitation

    Temperature is a key factor in determining the distributions of adult tuna.

    “Temperature is a key factor in determining the distributions of adult tuna (Worm et al. 2005, Boyce et al. 2008, Tittensor et al. 2010), as well as of larvae (present study).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Worm et al. 2005 source
    • cites Boyce et al. 2008 source
    • cites Tittensor et al. 2010 source
  • Classified as probably not a substantial claim. 27
  • May combine two claims. 37

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

    Interpretationcitation

    Higher temperatures are expected to increase metabolic costs in tuna larvae, as observed in scombrid larvae.

    “The temperature effects on meta bolism have not been specifically studied in tuna larvae; however, higher temperatures are ex pected to increase metabolic costs, as has been observed in scombrid larvae (Giguère et al. 1988).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Giguère et al. 1988 source

  • Classified as probably not a substantial claim.

    Premisecitation

    The ocean triad hypothesis suggests tuna spawning generally occurs in areas with mesoscale oceanographic features such as fronts and eddies.

    “The ocean triad hypothesis suggests tuna spawning generally occurs in areas with mesoscale oceanographic features such as fronts and eddies (Bakun 2006).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Bakun 2006 source

      The “Illustration: North Atlantic bluefin tuna” section links bluefin spawning areas to fronts and mesoscale eddies, and the “Illustration: North Pacific albacore tuna” section describes another favourable eddy-associated larval habitat. The paper presents these as examples of ocean-triad processes, but does not establish that tuna generally spawn in such areas across species. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S1 (asserted). May combine two claims.

    Premisecitation

    Eddies are associated with high productivity, increasing the chances of larval survival.

    “Bakun (2006) proposed that eddies are associated with high productivity, increasing the chances of larval survival.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Bakun 2006 source

      The MESOSCALE EDDIES section says eddy processes can produce high biological productivity and reproductive success. But OPPORTUNITY AND ADVANTAGE (p. 117) cautions that food-rich conditions can also attract predators: improved larval survival depends on adequate food coinciding with sufficiently low predation, not productivity alone. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    Peaks of food abundance during both the planktivorous and the piscivorous stages of larval development may be a determinant of survival in these oligotrophic areas.

    “Peaks of food abundance during both the planktivorous and the piscivorous stages of larval development may be a determinant of survival in these oligotrophic areas (Reglero et al. 2011).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Reglero et al. 2011 source

      The Model simulations section links zooplankton density to food limitation during planktivory, and Summary and broader potential implications links prey density to mortality during piscivory. The paper therefore supports a role for food availability, but the passages do not identify peaks of food abundance at both stages as a determinant of survival. Page numbers were not provided in our copy. (LLM, conf=0.78)

      Experimental — accuracy not yet measured

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

    Premisecitation

    A preference for similar ranges of EKE has been reported for adult breeding Atlantic bluefin tuna distributions in the Gulf of Mexico, and mesoscale activity is commonly found in areas with larvae.

    “A preference for similar ranges of EKE has been re ported for adult breeding Atlantic bluefin tuna distributions in the Gulf of Mexico (Teo et al. 2007), and mesoscale activity is commonly found in areas with larvae (Muhling et al. 2013).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Teo et al. 2007 source
    • cites Muhling et al. 2013 source

  • May combine two claims.

    Premisecitation

    Tuna species show a preference for mesoscale structures with moderate activity to spawn, but avoid high EKE.

    “In general, tuna species show a preference for mesoscale structures, with moderate activity to spawn, but avoid high EKE (Teo et al. 2007, Reglero et al. 2012, Muhling et al. 2013); one factor involved could be the opportunity to disperse during the larval stage.”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites Teo et al. 2007 source
    • cites Reglero et al. 2012 source

      The Spatial portioning section says western-stock bluefin tuna breed close to mesoscale structures, and the Results report the best albacore model fit at slow to intermediate geostrophic velocities. But the Results also report a preference for high frontal activity in bluefin tuna and a positive relationship with high geostrophic velocities in bullet tuna. The paper does not establish that tuna species generally avoid high eddy kinetic energy (EKE). (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites Muhling et al. 2013 source

      The Discussion (page unavailable) reports that Atlantic bluefin tuna larvae in both study areas were most likely to occur in regions of moderate mesoscale activity, not strong directional flow; it also infers that adults concentrated spawning in moderate currents away from large energetic eddies. The paper does not establish this preference for tuna species generally or specifically measure avoidance of high eddy kinetic energy (EKE). (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data

    Skipjack, yellowfin and bigeye tuna were distributed throughout the tropics in every ocean, both as adults and larvae.

    “Skipjack, yellowfin and bigeye tuna were, in contrast, distributed throughout the tropics in every ocean, both as adults and larvae (Fig. 3a-c), while albacore larvae were also found at higher latitudes in the Mediterranean Sea with low occurrences in the equatorial zone (Fig. 3d).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Maximum probabilities of occurrence of larvae for most species were predominantly in SSTs between 27.4 and 27.8°C, whereas Atlantic and Pacific bluefin tuna were, on average, found at slightly colder temperatures (26.5 and 25.3°C, respectively).

    “Maximum probabilities of occurrence of larvae for most of the species were pre dominantly in SSTs between 27.4 and 27.8°C, whereas Atlantic and Pacific bluefin tuna were, on average, found at slightly colder temperatures (26.5 and 25.3°C, respectively).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Bigeye tuna were predicted to occur in every ocean, being distributed in the equatorial area, but predicted probabilities of occurrence were lower than those for skipjack and yellowfin tuna.

    “Bigeye tuna were predicted to occur in every ocean, being distributed in the equatorial area, but predicted probabilities of occurrence were lower than those for skipjack and yellowfin tuna (Fig. 7c).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Tuna larvae occur within the adults' distributional range, but are restricted to lower latitudes and higher water temperatures than adults.

    “Our results showed that tuna larvae occur within the adults' distributional range, but were restricted to lower latitudes and higher water temperatures than adults, largely consistent with Schaefer's 'temperature hypothesis'.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schaefer 2001 source

  • May combine two claims.

    Findingown data

    The prediction for albacore matched well with the absence of larvae in the equatorial zone, predominantly in areas with lower EKE and higher temperature, which was also found at northern latitudes.

    “The prediction for albacore matched well with the absence of larvae in the equatorial zone, predominantly in areas with lower EKE and higher temperature, which, in addition, was also found at northern latitudes (Figs.7d, 8 & 9).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

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

    Findingown data

    Atlantic bluefin tuna larvae were present in the Mediterranean Sea, but no predictions were obtained for this area because EKE values were not available.

    “Atlantic bluefin tuna larvae were also present in the Mediterranean Sea, but no predictions were ob tained for this area, since EKE values were not available.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Tuna larvae preferred warmer waters and tended to have narrower temperature tolerances, on average, than adults.

    “Tuna larvae preferred warmer waters and tended to have narrower temperature tolerances, on average, than adults (Table 3).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingnone given

    For albacore and southern bluefin tuna, the larval thermal range was found to extend above the upper thermal range of adults (25.2°C compared to 30°C in albacore, 28.4°C compared to 30.2°C in southern bluefin tuna).

    “For albacore and southern bluefin tuna, the larval thermal range was found to extend above the upper thermal range of adults (25.2°C compared to 30°C in albacore, 28.4°C compared to 30.2°C in southern bluefin tuna).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Spatial patterns of skipjack and yellowfin tuna were predicted well by the model, with larvae distributed broadly throughout the tropics.

    “Spatial patterns of skipjack and yellowfin tuna were predicted well by the model, with larvae distributed broadly throughout the tropics (Fig. 7a,b).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Tuna larvae generally occupy latitudes between 30°S and 30°N, except in the Mediterranean Sea where larvae are found upwards of 35°N, whereas adults range from 60°S to 60°N.

    “In general, tuna larvae were found to occupy latitudes between 30°S and 30°N (with the exception of the Mediterranean Sea where larvae are found upwards of 35°N), whereas adults were found to have a much larger range, from 60°S to 60°N (Figs. 2 & 3).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The probability of larvae occurring in a cell increased with EKE, linearly in Atlantic bluefin tuna, and plateauing around intermediate values of 0.01 to 0.06 m2 s-2 in Pacific bluefin tuna, but EKE was not significant in explaining the occurrence of southern bluefin tuna.

    “The probability of larvae occurring in a cell increased with EKE, linearly in Atlantic bluefin tuna (Fig. 4c), and plateauing around intermediate values of 0.01 to 0.06 m 2 s -2 in Pacific bluefin tuna (Fig. 4d), but were not significant in explaining the occurrence of southern bluefin tuna (Table 1).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    All tuna species showed similar maximum temperature tolerances of ≥28.5°C, but different minima: <22°C in skipjack tuna, yellowfin tuna, albacore, bigeye tuna and Pacific bluefin tuna and >24°C in Atlantic bluefin tuna and southern bluefin tuna.

    “All species showed similar maximum temperature tolerances of ≥28.5°C, but different minima: < 22°C in skipjack tuna, yellowfin tuna, albacore, bigeye tuna and Pacific bluefin tuna and > 24°C in Atlantic bluefin tuna and southern bluefin tuna (Fig 10, Table 3).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    The probability of larval occurrence was positively and linearly related to temperature in Atlantic bluefin tuna and southern bluefin tuna, but temperature did not significantly explain the occurrence of Pacific bluefin tuna.

    “The probability of larval occurrence was positively and linearly related to temperature in Atlantic bluefin tuna (Fig. 4a) and southern bluefin tuna (Fig. 4b) larvae, but did not significantly explain the occurrence of Pacific bluefin tuna (Table 1).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Albacore larvae were also found at higher latitudes in the Mediterranean Sea with low occurrences in the equatorial zone.

    “Skipjack, yellowfin and bigeye tuna were, in contrast, distributed throughout the tropics in every ocean, both as adults and larvae (Fig. 3a-c), while albacore larvae were also found at higher latitudes in the Mediterranean Sea with low occurrences in the equatorial zone (Fig. 3d).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Tuna larvae are not typically found in areas of low EKE, and have the highest probability of occurrence at intermediate values of EKE.

    “According to our results, tuna larvae are not typically found in areas of low EKE, and have the highest probability of occurrence at intermediate values of EKE.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingown data

    Albacore showed the completely opposite pattern: their larvae are distributed above and below 10°N and 10°S, avoiding the equatorial waters, a spatial pattern that is well modeled when the negative influence of EKE in the occurrence of albacore larvae is taken into account.

    “However, albacore showed the completely opposite pattern.Their larvae are distributed above and below 10°N and 10°S, avoiding the equatorial waters, a spatial pattern that is well modeled when the negative influence of EKE in the occurrence of albacore larvae is taken into account.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Findingreasoning

    Here we have identified oceanographic parameters (mesoscale eddies and SST) that can easily be measured by remote sensing and features (eastern boundary currents, semi-enclosed seas) that should be considered when determining areas of critical habitat for tuna larvae.

    “Here we have identified oceanographic parameters (mesoscale eddies and SST) that can easily be measured by remote sensing and features (eastern boundary currents, semi-enclosed seas) that should be considered when determining areas of critical habitat for tuna larvae.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.
    • Rests on an assumption: The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.
    • Rests on an assumption: The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

  • May combine two claims.

    Findingnone given

    Eastern boundary currents have EKE values < 0.01 to 0.02 m2 s-2 and are associated with colder temperatures.

    “In contrast, eastern boundary currents have EKE values < 0.01 to 0.02 m 2 s -2 and are associated with colder temperatures.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.
    • Rests on an assumption: The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.
    • Rests on an assumption: The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

  • May combine two claims.

    Findingown data

    A combination of temperature > 20°C and intermediate EKE provided the greatest explanatory power for most larval distributions, except for the 3 bluefin tuna species and albacore.

    “A combination of the 2 hypotheses (areas delineated both by temperature > 20°C and with an intermediate EKE) provided the greatest explanatory power for most larval distributions, except for in the 3 bluefin tuna species, which had more restricted spawning locations, and albacore, which preferred low EKE values.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.
    • Rests on an assumption: The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.
    • Rests on an assumption: The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

  • May combine two claims.

    Findingown data

    The probability of larval occurrence was linear and positively related to EKE in Atlantic bluefin tuna, but linear and negatively related in albacore.

    “The probability of larval occurrence was linear and positively related to EKE in Atlantic bluefin tuna, but linear and negatively related in albacore.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.
    • Rests on an assumption: The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.
    • Rests on an assumption: The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

  • May combine two claims.

    Findingown data

    The distributional range in tunas during the larval phase was related to temperature, with a lower limit of 20°C.

    “The distributional range in tunas during the larval phase was related to temperature (temperature hypothesis), though with a lower limit (20°C) than the 24°C traditionally used to delineate tuna spawning-ground boundaries (Schaefer 2001).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.
    • Rests on an assumption: The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.
    • Rests on an assumption: The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

  • May combine two claims.

    Interpretationown data

    Both SST and EKE were major predictors for the spatial distribution of tuna larvae, but the trends of the 2 environmental predictors differed among species.

    “Both SST and EKE were found to be major predictors for the spatial distribution of tuna larvae, but the trends of the 2 environmental predictors differed among species.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Interpretationown data

    The lower temperature tolerance for tuna larvae appears to be 20°C, at least for some species, though most positive occurrences were observed in warmer temperatures.

    “According to our results, the lower temperature tolerance for tuna larvae appears to be 20°C, at least for some species, though most positive occurrences were observed in warmer temperatures.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

  • May combine two claims.

    Interpretationcitation

    Broader larval distributions were found for species that mature early in life and do not attain a large size, in contrast to the larger tuna species, which mature at an older age and have a narrower distribution as larvae, a pattern that correlates with tropical versus temperate tuna.

    “Broader larval distributions were found for species that mature early in life and do not attain a large size, in contrast to the larger tuna species, which mature at an older age and have a narrower distribution as larvae (Fromentin & Fonteneau 2001), a pattern that correlates with tropical versus temperate tuna.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Fromentin & Fonteneau 2001 source
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

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

    Study design and conductnone given

    Skipjack tuna benefits from the most extensive sampling at large and regional scales.

    “This species benefits from the most extensive sampling at large and regional scales.”
    Quote in the paperNot a substantial claim

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

    Study design and conductcitation

    Yellowfin tuna can usually be identified using the works by Matsumoto (1958) and Matsumoto et al. (1972).

    “This species can usually be identified using the works by Matsumoto (1958) and Matsumoto et al. (1972).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Matsumoto (1958)
    • cites Matsumoto et al. (1972)

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

    Study design and conductreasoning

    In some areas, albacore is usually included in the group Thunnus sp.

    “Therefore, in some areas, it is usually in clud ed in the group Thunnus sp.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Skipjack tuna larvae have a forebrain pigment that helps separate them from Thunnus species.

    “This species has a forebrain pigment that helps to separate them from Thunnus species (Richards 2006).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Richards 2006

      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).

    Study design and conductcitation

    Albacore larvae have been described by Matsumoto et al. (1972), Alemany (1997) and Richards (2006).

    “Albacore larvae have been de scribed by Matsumoto et al. (1972), Alemany (1997) and Richards (2006).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Matsumoto et al. (1972)
    • cites Alemany (1997)

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

    • cites Richards (2006)

      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).

    Premisecitation

    An increase of water temperatures before and during spawning is needed for adult tunas to release eggs.

    “An increase of water temperatures before and during spawning is needed for the adult tunas to release eggs (Margulies et al. 2007).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Margulies et al. 2007

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

  • May combine two claims.

    Study design and conductcitation

    Bigeye tuna larvae have been reported in the Gulf of Mexico, but further molecular analyses did not identify bigeye tuna in the Strait of Florida.

    “Bigeye tuna larvae have been reported in the Gulf of Mexico (Nishikawa et al. 1985, Estévez et al. 1993), but further molecular analyses did not identify bigeye tuna in the Strait of Florida (Richardson et al. 2006).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Nishikawa et al. 1985

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

    • cites Estévez et al. 1993

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

    • cites Richardson et al. 2006

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

  • May combine two claims.

    Interpretationown data

    Global patterns in larval distribution were easier to predict in skipjack and yellowfin tuna than in bluefin tuna species, where spawning areas and larval habitats appear much more spatially constrained.

    “However, the global patterns in larval distribution were easier to predict in skipjack and yellowfin tuna than in bluefin tuna species, where spawning areas and larval habitats appear much more spatially constrained.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.
    • Rests on an assumption: Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.
    • Rests on an assumption: Species-level morphological identifications in the source articles are accurate enough for the analyses.

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

    Study design and conductcitation

    Molecular markers have confirmed skipjack tuna identifications based on morphological traits in the Pacific Sea and the Gulf of Mexico.

    “The use of molecular markers is rare but has confirmed skipjack identifications based on morphological traits in the Pacific Sea (Paine et al. 2008) and the Gulf of Mexico (Richardson et al. 2010).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Paine et al. 2008 source
    • cites Richardson et al. 2010 source

  • May combine two claims.

    Study design and conductnone given

    The combined database shows good spatial coverage, though individual surveys were very fragmented spatially and temporally and were not coordinated internationally.

    “The combined database shows good spatial coverage, though individual surveys were very fragmented spatially and temporally and were not coordinated internationally.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    Temperature has a consistent and dominant role in structuring broad-scale marine diversity patterns.

    “In general, temperature has a consistent and dominant role in structuring broad-scale marine diversity patterns (Tittensor et al. 2010).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Tittensor et al. 2010 source

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

    Study design and conductcitation

    Albacore may be a problem where both species co-occur, but not in the Mediterranean where only albacore is present and readily identified.

    “This may be a problem where both species co-occur, but not in the Mediterranean where only albacore is present and readily identified (Alemany 1997).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Alemany 1997

      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). May combine two claims.

    Premisecitation

    Oceanographic discontinuities have been suggested to limit the range distribution of marine species by acting as a boundary, but also through their influence on larval dispersal and recruitment.

    “In addition, oceanographic discontinuities have been suggested to limit the range distribution of marine species by acting as a boundary, but also through their influence on larval dispersal and recruitment (Gaylord & Gaines 2000).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Gaylord & Gaines 2000 source

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

    Study design and conductnone given

    Matsumoto et al. (1972) is usually used for species identification of bigeye tuna and to determine its distribution in regional studies in the Pacific and Indian Oceans.

    “Matsumoto et al. (1972) is usually used for species identification of bigeye tuna and to determine its distribution in regional studies in the Pacific and Indian Oceans.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Matsumoto et al. (1972)

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

    Study design and conductcitation

    Identifications of yellowfin tuna benefit from descriptions of individuals cultured in the laboratory.

    “Identifications of yellowfin tuna also benefit from the descriptions of individuals cultured in the laboratory (e.g.Margulies et al. 2007).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Margulies et al. 2007

      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

    The preference of albacore for regions with low EKE values may be an adaptation to separate their larval habitat from that of the other species.

    “The preference of albacore for regions with low EKE values may be an adaptation to separate their larval habitat from that of the other species.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    A trade-off between predation and food availability may be the reason why larvae prefer mesoscale structures within broad-scale oligotrophic areas.

    “A trade-off between predation and food availablity may be the reason why larvae prefer mesoscale structures within broad-scale oligotrophic areas.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisenone given

    This study provides the first compilation of published data for tuna larvae on a broad spatial scale.

    “This study provides the first compilation of published data for tuna larvae on a broad spatial scale.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Regions of high EKE could be less suitable for spawning if larvae end up in less optimal areas for later growth and survival as a result of the influence of strong currents on transport.

    “Regions of high EKE could be less suitable for spawning if larvae end up in less optimal areas for later growth and survival as a result of the influence of strong currents on transport.”
    Quote in the paperSubstantial claim

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

    Interpretationreasoning

    If intermediate EKE values associated with mesoscale structures influence the spatial distribution of feeding resources, this may increase larval survival.

    “If intermediate EKE values associated with mesoscale structures influence the spatial distribution of feeding resources, this may increase larval survival.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    There is very limited scientific information on the spatio-temporal spawning patterns of tuna species and strong uncertainties in knowledge of many biological parameters, including reproduction, of tuna species.

    “There is very limited scientific information on the spatio-temporal spawning patterns of tuna species (Schaefer 2001) and strong uncertainties in our knowledge of many biological parameters, including reproduction, of tuna species.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schaefer 2001 source

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

    Interpretationcitation

    There would be low food availability and, consequently, low predator abundances, as suggested by the loophole hypothesis.

    “Thus, there would be low food availability and, consequently, low predator abundances, as suggested by the socalled 'loophole hypothesis ' (Bakun & Broad 2003, Irigoien et al. 2007).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Bakun & Broad 2003 source
    • cites Irigoien et al. 2007 source

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

    Premisecitation

    One constraint on the implementation of HSMPAs is limited knowledge regarding the biodiversity of oceanic species and the identification of the parameters that should be measured.

    “One constraint on the implementation of HSMPAs is limited knowledge regarding the biodiversity of oceanic species and the identification of the parameters that should be measured (UNEP-WCMC 2008).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites UNEP-WCMC 2008

      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). May combine two claims.

    Interpretationreasoning

    EKE obtained from sea-surface height anomalies may be a good indicator of mesoscale activity in most of the oceans, but in confined areas mesoscale structures can be induced by topography or occur at a smaller scale than the grid size used in this study.

    “EKE obtained from sea-surface height anomalies may be a good indicator of mesoscale activity in most of the oceans.But in such confined areas mesoscale structures can be induced by topography or occur at a smaller scale than the grid size used in this study.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    One factor involved in the preference for mesoscale structures could be the opportunity to disperse during the larval stage.

    “In general, tuna species show a preference for mesoscale structures, with moderate activity to spawn, but avoid high EKE (Teo et al. 2007, Reglero et al. 2012, Muhling et al. 2013); one factor involved could be the opportunity to disperse during the larval stage.”
    Quote in the paperNot a substantial claim
55 of 55

  • The paper relies on this without support.

    Seasonal SST and EKE averaged over 5° × 5° grid cells represent the environmental conditions relevant to tuna larval occurrence.

    “Both monthly EKE and SST values were averaged at each 5° × 5° cell of the analysis grid to obtain seasonal (3 mo) data.”

  • The paper relies on this without support.

    Larval presence/absence records compiled from different years and sources are comparable enough to model global environmental relationships.

    “Standardized data on larval densities were not available for comparison across studies and oceans; hence, we were forced to focus on larval presence records only.”
    “Furthermore, larval sampling cruises were not routinely recorded over the years in different areas, so we have combined different sampling years, with the earliest cruises dating from the 1920s and the latest from the 2000s.”

  • The paper relies on this without support.

    Species-level morphological identifications in the source articles are accurate enough for the analyses.

    “Larval tuna identification at species level can be problematic when based on morphological descriptions, especially in the Gulf of Mexico (Richards et al. 1990).”
    “We have carefully reviewed the basis for taxonomical descriptions in the articles used as data sources for our analyses.”

  • The paper relies on this without support.

    Sampled cells where no tuna larvae were caught represent true absence of tuna larvae.

    “Sampled cells where no tuna larvae were obtained from geo-referenced icthyoplankton surveys are shown in dark orange.Areas with missing data are shown in white”

  • The paper relies on this without support.

    The compiled larval data from different sources and time periods are comparable and can be combined into a single global analysis.

    “A total of 1678 grid cells, excluding land cells, between 70°S and 70°N were mapped according to the available information on the presence or absence of tuna larvae for every species.”

  • The paper relies on this without support.

    The generalized additive models with SST and EKE capture the main environmental drivers of larval occurrence.

    “predicted values were derived from a generalized additive model including SST and EKE as predictor variables when significant.”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • 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).”

    From Impacts of phytoplankton availability on bigeye tuna (Thunnus obesus) recruitment in the Indian Ocean (2024) · cites this paper as Reglero et al., 2014

    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

  • 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).”

    From Impacts of phytoplankton availability on bigeye tuna (Thunnus obesus) recruitment in the Indian Ocean (2024) · cites this paper as Reglero et al., 2014

    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

  • To spawn, all tuna species return to tropical or subtropical locations, which are typically oligotrophic and warm.

    “However, to spawn, all tuna species return to tropical or subtropical locations, which are typically oligotrophic and warm (Sund et al., 1981;Reglero et al., 2014).”

    From Evolutionary and ecological constraints of fish spawning habitats (2015) · cites this paper as Reglero et al., 2014

  • 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).”

    From Impacts of phytoplankton availability on bigeye tuna (Thunnus obesus) recruitment in the Indian Ocean (2024) · cites this paper as Reglero et al., 2014

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.

  • Temperature is called significant for every species despite the Pacific bluefin result

    Major

    The discussion claims a significant temperature effect in all species, whereas the results explicitly say temperature did not significantly explain Pacific bluefin larval occurrence.

  • Southern bluefin EKE is called nonsignificant despite its reported p-value

    Major

    The results say EKE was not significant for southern bluefin tuna, but Table 1 reports an EKE probability of 0.003.

  • Skipjack model table lists SST twice

    Minor

    Table 2 gives two different SST rows for skipjack tuna, although the stated model contains one SST term alongside area and EKE. The table does not explain which SST result applies.

  • The final sampling season has two different end months

    Minor

    The methods define the last sampling season as October to November, while the seasonal environmental-data figure defines it as October to December.

4 of 4

Cites

Flagged first, then by citations

3 of the 87 references couldn’t be matched to a known paper.

Research works printed but not linked: 3

  1. Alemany F (1997) Ictioplancton del Mar Balear. PhD thesis, University of Illes Balears, Palma de Mallorca
  2. 10.3989/scimar03759.28A · DOI
  3. UNEP-WCMC (2008) National and regional networks of marine protected areas: a review of progress. UNEP-WCMC, Cambridge

Cited by

Sorted by citations

Related

Authors
Reglero, P., Tittensor, D., Álvarez-Berastegui, D., Aparicio-González, A., & Worm, B.
Venue
Marine Ecology Progress Series
Publisher
Inter-Research Science Center
Published
2014-03-31
Volume
501
Pages
207-224
ISSN
  • 0171-8630 (ISSN-L)
  • 1616-1599
DOI
10.3354/meps10666
OpenAlex
W2312411547
Semantic Scholar
93d5321db6e8f91ce9daddbb68801a21955350a2
Cited by
106
References
87
Citations by year
2026: 12 · 2025: 9 · 2024: 9 · 2023: 6 · 2022: 9 · 2021: 14 · 2020: 11 · 2019: 7 · 2018: 11 · 2017: 6 · 2016: 6 · 2015: 3 · 2014: 3
FWCI
3.02
Type
journal article
Language
en
Open access
Locations
  • Marine Ecology Progress Series (publishedVersion)
  • DIGITAL.CSIC (Spanish National Research Council (CSIC)) (submittedVersion, cc-by-nc-nd)
Funders
  • California Institute of Technology
  • National Oceanic and Atmospheric Administration
  • Jet Propulsion Laboratory
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
  • Physical Sciences › Earth and Planetary Sciences › Oceanography › Oceanographic and Atmospheric Processes
Keywords
tuna larvae, spawning grounds, larval distribution, eddy kinetic energy, western boundary currents, bluefin tuna, albacore tuna, critical habitat, water temperature, remote sensing

About these checks

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.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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