The number of seabirds and sea mammals killed by marine plastic pollution is quite small relative to the catch of fish

Disclaimer: plastic pollution may well kill way more animals besides seabirds and sea mammals. There are 6.20*10^14 wild fish and 1.00*10^20 wild marine arthropods, but only 6.75*10^11 wild mammals.

Summary

  • 1 kg of plastic is emitted to the ocean per capita per year[1].

  • 0.0001 seabirds and 0.00001 sea mammals are killed by marine plastic pollution per capita per year.

  • 200 wild fish are caught per capita per year.

  • The catch of wild fish is 2 M times as large as the number of seabirds, and 20 M times as large as the number of sea mammals killed by marine plastic pollution.

The data and calculations are presented below.

Data

  • The plastic emitted to the ocean in 2010 was 8 million tonnes according to OWID (PEO = 8 Mt).

  • The world population in 2010 was 6.92 billion according to The World Bank (WP = 6.92 G).

  • Marine plastic debris kills up to 1 million seabirds and 100 thounsand sea mammals each year according to the United Nations (SB = 1 M, and SM = 100 k).

  • The catch of wild fish is 0.97 to 2.7 trillion/​year according to fishcount.org (WFL = 0.97 T/​year to WFH = 2.7 T/​year).

Calculations

  • Plastic emitted to the ocean per capita in 2010 (PEOpC): PEO /​ WP = 8 Gkg /​ (6.92 G) = 1.16 kg.

  • Plastic emitted to the ocean to cause one death of a seabird (PEOpDSB): PEO /​ SB = 8 Mt /​ (1 M) = 8 t.

  • Plastic emitted to the ocean to cause one death of a sea mammal (PEOpDSM): PEO /​ SM = 8 Mt /​ (0.1 M) = 80 t.

  • Seabirds killed by plastic marine pollution in 2010, per capita (DSBpC): PEOpC /​ PEOpDSB = 1.16 /​ (8 k) = 145 μ (145 seabirds killed per million people).

  • Sea mammals killed by plastic marine pollution in 2010, per capita (DSMpC): PEOpC /​ PEOpDSM = 1.16 /​ (80 k) = 14.5 μ (14.5 sea mammals killed per million people).

  • Wild fish caught per year (WF): (WFL * WFH)^0.5 = (0.97 * 2.7)^0.5 T = 1.62 T.

  • Catch of wild fish per capita per year (WFpC): WF /​ WP = 1.62 T /​ (6.92 G) = 234.

  • Ratio between the catch of wild fish and the number of seabirds killed by marine plastic pollution: WFpC /​ DSBpC = 234 /​ (145 μ) = 1.62 M.

  • Ratio between the catch of wild fish and the number of sea mammals killed by marine plastic pollution: WFpC /​ DSMpC = 234 /​ (14.5 μ) = 16.2 M.

This work is licensed under a Creative Commons Attribution 4.0 International License.

  1. ^

    1 kg is the global value, and it is much smaller for many countries. Most of the countries emit less than 0.1 % of the plastic waste to the ocean (see this map), although 3 % of the global plastic waste is emitted to the ocean.