Research ArticleCONSERVATION ECOLOGY

Predatory fish depletion and recovery potential on Caribbean reefs

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Science Advances  01 Mar 2017:
Vol. 3, no. 3, e1601303
DOI: 10.1126/sciadv.1601303
  • Fig. 1 Biomass of reef fishes by sites and trophic level.

    Mean biomass of trophic guilds per reef site + 1 SE for total fish biomass. Sites are organized from low to high total fish biomass. Note that the observed biomass distribution is not meant to be representative of the Caribbean because sites were not randomly selected, that is, the higher biomass sites were specifically targeted to quantify reef fish structure at locations with limited fishing. Moreover, we did not sample the Caribbean regions where overfishing is the most severe, for example, Jamaica. Trophic categories were based on dietary information. No-take zones (NTZs) and minimum fished marine protected areas (MPAs) are noted as reserves (gray dots). For site abbreviations and protection level information, see table S2. For species list in each group, see table S3.

  • Fig. 2 Coefficient estimates of generalized mixed-effects models.

    Mean coefficient estimates (±95% confidence interval) of top models (ΔAICc < 2, where ΣwAICc > 0.95) for apex predators, piscivore-invertivores (Pisc-invertivores), and total predators. Longer confidence intervals are truncated to improve visualization. Black circles and lines are estimates of the models that included all study sites (model set A). Blue squares and lines are for models within marine reserves (model set B). Gray horizontal lines divide variables by anthropogenic (A), physical (B), biological (C), and management categories (D). Only estimates that improved model fit are shown. Poaching high, high level of poaching.

  • Fig. 3 Estimated biomass of predatory reef fish in the absence of human activities.

    Boxplot of the observed (orange) and predicted (light blue) median (50 and 99% quartiles) of predatory reef fish biomass across survey sites (ordered from lowest to highest biomass). Horizontal dashed lines are the observed (orange) and predicted (light blue) regional means. Predicted biomass was based on the best explanatory model given, with no coastal development within 50 km (that is, in the absence of humans) and every site considered as an NTZ (that is, no fishing). On the basis of the predictive models, 60 to 90% of the potential predatory fish biomass has been extracted in three of four reefs. NTZs and MPAs with minimum fishing are noted as marine reserves (gray dots). For better representation, y axis is in log scale. For site codes, see table S2.

  • Fig. 4 Distribution of survey locations.

    For site abbreviations, survey dates, coordinates, and protection level, refer to table S2. NTZs and minimum fished MPAs are represented with solid symbols. MBR, Mesoamerican Barrier Reef.

  • Table 1 Summary of generalized linear mixed-effects models.

    Results of the generalized linear mixed-effects model (GLMM) comparisons using Akaike’s information criterion corrected for small sample sizes (AICc) for apex predators, piscivore-invertivores, and total predators. Only the null model, an exploratory model that outperformed the null model, and final models (ΔAICc < 2, where ΣwAICc > 0.95) are shown. Model set A included all sites, whereas model set B included sites within reserves. Parameters are as follows: model maximum log-likelihood (LL), degrees of freedom (df), change in AICc (ΔAICc), AICc weights (wAICc), and pseudocoefficient of determination for GLMMs (R2). Models are ordered by increasing wAICc, and the final models show bolded wAICc. Model covariates include the following: Ag, reserve age; Al, macroalgae; Db, distance to reef break; De, depth; Dm, distance to mangrove; Cd, coastal development within 50 km; Cl, cultivated land within 50 km; Co, corals; He, herbivores; Hu, human population density within 50 km; In, invertivores; Go, gorgonians; Ma, mangrove perimeter within 5 km; Tp2, quadratic term of minimum monthly mean sea surface temperature; Om, omnivores; Pi, piscivore-invertivores; Pl, planktivores; Po, poaching level within reserve; Pp, net primary production; Pr, protection level; Ra, reef area within 5 km; Ru, reef complexity; Si, reserve size; We, wave exposure. See table S4 for units.

    ModelsLLdfΔAICcwAICcR2
    Apex predators
    Set A
      Null−324.9620.160.00
       Cd + Tp2 + Ma + Co + Go + Pi + Pr−312.41412.000.000.49
       Cd + Ru + Co + Pi + Pr−309.1121.100.180.49
       Cl + Pp + Ru + Co + Pi + Pr−307.7130.400.250.50
       Cl + Ru + Co + Pi−310.9100.350.260.49
       Cd + Tp2 + Ru + Co + Pi−309.6110.000.310.49
    Set B
      Null−129.5614.30.00
       Cd + Ru + Ma + Go + Pi + In + Om−121.31314.00.000.45
       Ru + Ma + Co + Pi + Po−117.2111.090.140.42
       Hu + Ru + Pi−119.490.680.170.42
       Cl + Ru + Co + Pi−118.0100.280.210.42
       Pp + Ru + Co + Po−117.9100.120.230.43
       Cd + Ru + Co + Go + Pi−116.7110.000.240.44
    Piscivore-invertivore
    Set A
      Null−252.6565.680.00
       Cd + Pp + Tp2 + We + Ru + Ma + Co + Al + Go + In + Om + Pl + He + Pr−207.1206.740.030.57
       Cd + Tp2 + Ru + Co + Go + In + Om + Pl + He + Pr−208.1160.000.970.56
    Set B
      Null−85.91518.810.00
       Cd + Tp2 + We + Ru + Co + Go + In + Om + Pl + He + Po−65.69177.960.010.58
       Hu + Ru + Ma + Co + In + Om + Po−68.29120.640.420.54
       Cd + Ru + Co + In + Om + Po−69.85110.000.570.55
    Total predators
    Set A
      Null−249.0545.690.00
       Cd + Pp + Tp2 + We + De + Ru + Db + Dm + Ma + Co + Al + Go + In + Om + Pl + He + Pr−219.22119.770.000.60
       Cd + Tp2 + Ru + Co + Go + In + Om + Pl + He + Pr−214.9160.001.000.61
    Set B
      Null−84.2958.140.00
       Cd + Ru + Ma + Co + Go + In + Om + Pl + He + Si + Ag + Po−71.49156.700.000.56
       Hu + Ru + Co + In + Om + Po−73.24112.300.230.53
       Cd + Ru + Co + In + Om + Po−74.39110.000.770.55

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1601303/DC1

    table S1. Estimates of current and potential average biomass (±SE) (in g m−2) of predatory reef fishes in the absence of humans (that is, coastal development) while categorizing every site as an NTZ (that is, no fishing).

    table S2. Study sites, site codes, regions, and protection level.

    table S3. Fish trophic guilds, species taxonomic information, and allometric parameters used to calculate biomass.

    table S4. Summary of preliminary, anthropogenic, physical, biotic, and management-related predictors used in the analysis.

    table S5. Spearman’s rank-order (rs) correlation matrix for response and explanatory variables.

    table S6. Covariate selection procedure for closely related variables for all predators and each predator group based on AICc (AIC-corrected for small samples).

    section S1. Detailed description of reef fish biomass spatial variation.

    section S2. Detailed results of the relationships between predatory fish biomass and cofactors.

    section S3. Detailed discussion of the relationships between predatory fish biomass and cofactors and their potential underlying mechanisms.

    section S4. Detailed description of covariates.

    section S5. Analysis and R code to predict total predator biomass in the absence of humans, considering all sites as no fishing areas based on the best explanatory model from Table 1.

    fig. S1. Boxplot of total fish.

    fig. S2. Scatterplots of the mean proportion of trophic guilds per site and survey year.

    fig. S3. Scatterplots of the mean biomass of predators (apex predator + piscivores-invertivore) and lower trophic guilds across sites.

    fig. S4. Main drivers of spatial variation in predatory reef fish biomass.

    fig. S5. Relationship between reef structural complexity and fish trophic guilds.

    fig. S6. Plots of residuals versus fitted values (left) and normal scores of standardized residual deviance (right) for the final models (sets A and B) of total predator biomass.

    fig. S7. Plots of the spline correlogram function against distance.

    References (75132)

  • Supplementary Materials

    This PDF file includes:

    • table S1. Estimates of current and potential average biomass (±SE) (in g m−2) of predatory reef fishes in the absence of humans (that is, coastal development) while categorizing every site as an NTZ (that is, no fishing).
    • table S2. Study sites, site codes, regions, and protection level.
    • table S3. Fish trophic guilds, species taxonomic information, and allometric parameters used to calculate biomass.
    • table S4. Summary of preliminary, anthropogenic, physical, biotic, and management-related predictors used in the analysis.
    • table S5. Spearman’s rank-order (rs) correlation matrix for response and explanatory variables.
    • table S6. Covariate selection procedure for closely related variables for all predators and each predator group based on AICc (AIC-corrected for small samples).
    • section S1. Detailed description of reef fish biomass spatial variation.
    • section S2. Detailed results of the relationships between predatory fish biomass and cofactors.
    • section S3. Detailed discussion of the relationships between predatory fish biomass and cofactors and their potential underlying mechanisms.
    • section S4. Detailed description of covariates.
    • section S5. Analysis and R code to predict total predator biomass in the absence of humans, considering all sites as no fishing areas based on the best explanatory model from Table 1.
    • fig. S1. Boxplot of total fish.
    • fig. S2. Scatterplots of the mean proportion of trophic guilds per site and survey year.
    • fig. S3. Scatterplots of the mean biomass of predators (apex predator + piscivores-invertivore) and lower trophic guilds across sites.
    • fig. S4. Main drivers of spatial variation in predatory reef fish biomass.
    • fig. S5. Relationship between reef structural complexity and fish trophic guilds.
    • fig. S6. Plots of residuals versus fitted values (left) and normal scores of standardized residual deviance (right) for the final models (sets A and B) of total predator biomass.
    • fig. S7. Plots of the spline correlogram function against distance.
    • References (75–132)

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