Over the past 100 years, large predator fish such as cod, tuna and groupers have declined by two-thirds, according to a new study by University of British Columbia researchers.

As humans have caught and consumed the large fish, small fish such as sardine, anchovy and capelin have more than doubled over the last century in the absence of the predators that feed on them. This has a huge impact on ecosystems globally.

In a statement, Prof. Villy Christensen of UBC’s Fisheries Centre said: “If the fishing-down-the-food-web trend continues, our oceans may one day become a ‘farm’ to produce feeds for the aquaculture industry.”

The study was presented recently at the American Association for the Advancement of Science (AAAS) Annual Meeting in Washington, DC. A team of scientists used more than 200 marine ecosystem models from around the world and extracted more than 68,000 estimates of fish biomass from 1880 to 2007.

Read more:
The Washington Post: Predator fish in oceans on alarming decline, experts say
The Fisheries Secretariat: New study highlights upset ecosystems in world oceans