Research ArticleAPPLIED ECOLOGY

The historical development of complex global trafficking networks for marine wildlife

See allHide authors and affiliations

Science Advances  27 Mar 2019:
Vol. 5, no. 3, eaav5948
DOI: 10.1126/sciadv.aav5948
  • Fig. 1 Derived tortoiseshell morphometrics show modern trade was dominated by juvenile turtles.

    (A) Lateral and central scutes of the hawksbill carapace, widely marketable in the tortoiseshell trade, are shown in color. (B) The relationship between SCL of an individual and the area (square centimeter) of each scute. (C) The relationship between individual length and total tortoiseshell mass. (D) On the basis of these relationships, the frequency of hawksbill turtle sizes recorded in one-seized shipment from the 1980s contained 1741 individuals and consisted of mostly large juveniles (average = 63.1-cm, SD = 10.3 SCL). See table S2 for model parameters.

  • Fig. 2 Demographically explicit exploitation scenarios roughly double estimates of population impact.

    Understanding the biological impact of tortoiseshell trade requires converting trade records (listed in mass of tortoiseshell) into number of turtles. We do this in four ways, left to right: (A) only large adults taken (size fixed at 80-cm SCL), (B) mixed adults taken (average = 80-cm SCL, SD = 4.3), (C) mixed-age classes dominated by juvenile turtles (reflects Fig. 1D; average = 63.1-cm SCL, SD = 10.3), and (D) fishing down the population [demographic depletion from scenarios (A) to (C) over the time series]. Median estimates (points) and locally estimated smoothing scatterplot (LOESS) models (curves) are shown with 95% confidence intervals for annual exports, total individuals exported (in 1000 turtles) under each scenario listed (with confidence interval) for three countries representative of each ocean basin—Indian (Madagascar), Atlantic (Costa Rica), and Pacific (New Caledonia).

  • Fig. 3 Over 150 years, approximately 9 million hawksbill turtles were traded globally.

    Stacked area curves of the estimated number of individuals harvested under the fishing down scenario (Fig. 2D) are shown for (A) pre-WWII and (B) over the entire time series for each ocean basin. (C) Basin-wide harvested totals over the time series. This shows the geographic expansion of the global trade in tortoiseshell and the marked increase in trade coinciding with the establishment of international wildlife protections.

  • Fig. 4 Historical patterns of tortoiseshell trade networks reflect modern IUU fishing.

    Chord diagrams show the increasing complexity of tortoiseshell trade routes from (A) 19th century, (B) before WWII 20th century, and (C) after WWII. Arrows are from source to destination country, arrow width is proportionate to the number of hawksbill sea turtles traded (10,000 turtles). Export-only countries are labeled in lower case, and all other countries are labeled in bold and are capitalized (two-letter United Nations country codes; full list provided in table S3). (D) Total number of hawksbill sea turtles exported under the fishing down scenario, shown for each country’s EEZ, and constrained to the species’ geographic range (30°N to 30°S). (E) Top 10 tortoiseshell-exporting countries, listed by descending rank, in millions of turtles. (F) Modern IUU fishing in million metric tons (MT) per year per EEZ, derived from published assessments (60). (G) The top 10 countries with the highest estimates of IUU fishing in their EEZs (from 2005 to 2010), ranked in descending order, in million metric tons per year. Countries in the top 10 for both (D) and (F) are bold in (E) and (G).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/3/eaav5948/DC1

    Fig. S1. Japan was the major importer of tortoiseshell from 1844 to 1992.

    Fig. S2. Turtle exports per country varied in relation to CITES trade ban.

    Fig. S3. Illegally trafficked hawksbill sea turtle parts and products are seized entering the United States from more than 70 countries.

    Fig. S4. Seized hawksbill sea turtles are trafficked to the United States largely by air transportation and in raw forms more frequently than processed tortoiseshell.

    Fig. S5. Power law models show the relationship between calculated precise and crude areas for individual scutes and scute groupings from hawksbill sea turtles.

    Fig. S6. Hawksbill sea turtle specimens used in this study were a range of sizes.

    Fig. S7. Demographically explicit scenarios produce different estimates of the number of hawksbill sea turtles harvested.

    Table S1. Hawksbill sea turtle export data curation methods.

    Table S2. Model parameters for tortoiseshell morphometric relationships in Fig. 1.

    Table S3. Complete list of United Nations country abbreviations (alpha 2) used in Fig. 4 and figs. S1 and S3.

    Dataset S1. Hawksbill sea turtle historical trade records.

    Dataset S2. Hawksbill sea turtle scute morphometrics.

    Dataset S3. U.S. seizure records of hawksbill sea turtles.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Japan was the major importer of tortoiseshell from 1844 to 1992.
    • Fig. S2. Turtle exports per country varied in relation to CITES trade ban.
    • Fig. S3. Illegally trafficked hawksbill sea turtle parts and products are seized entering the United States from more than 70 countries.
    • Fig. S4. Seized hawksbill sea turtles are trafficked to the United States largely by air transportation and in raw forms more frequently than processed tortoiseshell.
    • Fig. S5. Power law models show the relationship between calculated precise and crude areas for individual scutes and scute groupings from hawksbill sea turtles.
    • Fig. S6. Hawksbill sea turtle specimens used in this study were a range of sizes.
    • Fig. S7. Demographically explicit scenarios produce different estimates of the number of hawksbill sea turtles harvested.
    • Table S1. Hawksbill sea turtle export data curation methods.
    • Table S2. Model parameters for tortoiseshell morphometric relationships in Fig. 1.
    • Table S3. Complete list of United Nations country abbreviations (alpha 2) used in Fig. 4 and figs. S1 and S3.
    • Legends for dataset S1 to S3

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Dataset S1 (.csv format). Hawksbill sea turtle historical trade records.
    • Dataset S2 (Microsoft Excel format). Hawksbill sea turtle scute morphometrics.
    • Dataset S3 (Microsoft Excel format). U.S. seizure records of hawksbill sea turtles.

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article