Fisheries and Global Warming: Impacts on Marine Ecosystems and Food Security

author: Daniel Pauly, Fisheries Centre, University of British Columbia
published: Aug. 29, 2011,   recorded: October 2007,   views: 3807

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Downward swooping lines on the graphs say it all: The world’s fish populations, and hence its fisheries, are collapsing. Daniel Pauly has analyzed reams of data -- including number of boats fishing, their reported catch, the amount of fish thrown overboard -- from every significant fishing area of the world over 50-plus years, and has concluded that today, 30% of our fisheries have crashed, and that by 2048, if the trend continues, most will have disappeared.

This dismal turn of events comes courtesy of rampant over fishing, as well as wantonly wasteful fishing methods, says Pauly. Trawling rigs with miles of bottom-scraping nets may yield tons of desirable table fish, but also tons of byproduct—fish that don’t bring as much in the market. These get tossed overboard. In the early 90s, according to Pauly, 30 million tons of fish -- fully 1/4 of the world’s catch- -- was discarded. Improvements in technology such as GPS have only made matters worse.

There’s little awareness of the magnitude of the problem among Western countries, because there’s no sign of it in supermarkets, with fish department displays still spilling over. That’s because Europe and America have moved south for their fish, says Pauly. Europe is now plying the waters off Africa, leaving Guinea-Bissau, for instance, with only 7% of its fish. Americans increasingly eat South American and Asian fish. “The only place with no massive depletion is Brunei,” says Pauly, because “the Sultan doesn’t want boats between his oil wells.”

This collapse isn’t just a matter for fish eaters. As the top-paying table fish disappear, humans begin “fishing down the marine food web,” taking immature fish, and the fish that are prey to other species. Trawling in these already ecologically disturbed waters churns up sediment and takes out bottom dwelling fish, invertebrates and corals, which are essential to a healthy marine system. Biomass disappears, leaving dead zones. These ecosystems are primarily good for jellyfish and harmful algal blooms, says Pauly. The dead zone in the Gulf of Mexico is already the size of the state of Delaware.

Asked what fish it’s alright to eat, Pauly recommends chicken. In fact, he doesn’t believe “it’s an issue that can be fixed by private initiatives.” Effective action would mean eliminating fuel and other subsidies from the world’s fisheries, and permitting only small scale fisheries that engage in sustainable harvesting. But even this may not save certain species from extinction, as global warming pressures the world’s remaining fish species.

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