Data Visualization

Following the Science Is Critical for Atlantic Fish Stocks

Backsliding by ICCAT on science-based management threatens valuable fisheries, including prized bluefin tuna

Atlantic Ocean fish stocks


The methodology used to determine whether the International Commission for the Conservation of Atlantic Tunas followed scientific advice for 15 key Atlantic fish stocks* (plus sharks) consisted of a comparison of the advice against management measures over a 46-year period. Pew first consulted ICCAT’s Standing Committee on Research and Statistics (SCRS) report for each year from 1970 to 2016 to determine the scientific advice for each stock annually. Analysts then reviewed all stock-specific management measures (“Recommendations”) for each year, compared them with the scientific advice for the relevant year, and categorized the management action as one of the following:

  • Followed scientific advice. Recommendation was consistent with the SCRS management advice that year. If there was any question about whether it was consistent with the advice, it was recorded as “followed scientific advice.”
  • Did not follow scientific advice. The Commission adopted a Recommendation, but it was entirely or partially inconsistent with specific SCRS management advice that year.
  • No action: The SCRS gave specific management advice for a stock, but the Commission did not adopt any Recommendation for that stock.

For each year, Pew calculated the number and percent of Recommendations across all stocks that were consistent or inconsistent with the scientific advice (see bar chart and pie chart). The years before 1990 were excluded from the chart because of space constraints and because there were fewer Recommendations from 1970 to 1989. To develop the graphics showing population trends compared with adherence to the scientific advice for eastern bluefin tuna and North Atlantic swordfish, we used the population trend data directly from the most recent SCRS assessments (i.e., 2014 for eastern bluefin, 2013 for North Atlantic swordfish). Because these two stocks have been under quota management since 1996, years with no new Recommendation that were under quota management were classified and shaded based on whether the quota that year was consistent with the scientific advice.

*The 15 stocks were western Atlantic bluefin tuna, eastern Atlantic and Mediterranean bluefin tuna, bigeye tuna, yellowfin tuna, East Atlantic skipjack tuna, West Atlantic skipjack tuna, northern albacore, southern albacore, North Atlantic swordfish, South Atlantic swordfish, Mediterranean swordfish, blue marlin, white marlin, East Atlantic sailfish, and West Atlantic sailfish.

Download the full infographic (PDF).

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Leah Weiser

Senior Associate, Communications