Our oceans are emptying at an alarming rate. Oceanographers who monitor the Marine Trophic Index—a measure of the stability of the ocean’s food chain—have discovered a disturbing trend over the past 50 years: Humans are consuming marine animals in such massive numbers that the balance of ocean life has already been drastically upset since the beginning of large-scale industrial fishing in the 1950s.
The culprit for this sudden change in the ocean’s ecosystem is what University of British Columbia scientist Daniel Pauly describes as “fishing down the marine food webs.”1 What this means is that overfishing of alpha-predators like tuna and salmon—whose populations are rapidly dwindling—has caused us to begin eating lower down the ocean’s food chain. In the absence of their predators, species a step further down the chain experience a temporary population boom, creating an illusion of abundance for fishers, who begin the process of fishing them out of existence—and so on, all the way down to bottom-feeders and, eventually, plankton.
If this trend continues unabated, Pauly suggests, the future of seafood will be an unvarying supply of “jellyfish sandwiches.”2 An initially skeptical scientific community has confirmed Pauly’s fears, even going so far as to project an approximate date by which the world’s seafood supply will have run out based on the current rate of ocean fishing: That date could be as soon as 2050, according to a 2006 paper on the effects of overfishing published in the journal Science.3
And fish are not the only marine animals to suffer from aggressive commercial fishing practices. Techniques such as “bottom trawling” (in which nets are dragged thousands of miles across the ocean floor) and longlining (using large numbers of baited hooks on an extended line) indiscriminately destroy entire habitats of deep-sea species and devastate populations of dolphins, whales, sea turtles, seabirds, and other marine animals who are trapped in the nets or hooks as “bycatch.”
Unless we take immediate steps to change our fish-consumption habits, the long-term damage to our oceans’ ecosystems may well be irreversible.
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- 1. Daniel Pauly et al., “Fishing Down Marine Food Webs,” Science, February 6, 1998.
- 2. Robert McClure, “Jellyfish for Lunch? It's No Joke, Says Scientist,” Seattle Post-Intelligencer, May 4, 2004, http://seattlepi.nwsource.com/local/171765_fish04.html.
- 3. Boris Worm et al., “Impacts of Biodiversity Loss on Ocean Ecosystem Services,” Science, November 3, 2006.