Why should we worry about overfishing?

Why worry about overfishing? Why work on developing aquaculture and fish farming? To keep up with world appetites the global fish-farming industry will have to increase its growth. The reason is simple, current projections suggest that by 2030 the world’s population will have exceeded 8 billion people. Maintaining today’s consumption rates, of around 17 kilograms per person per year would require an extra 29 million tons of fish. Meanwhile, around half of all fish stocks have been deemed “fully exploited” by the FAO, with those deemed “over-exploited, depleted or recovering” now around 30%.

Studies by the University of British Columbia Fisheries Center show that globally we have run out of room to expand existing fisheries, due to past systematic expansion by industrialized fishing. The study showed that since 1950, fisheries expanded at the rate of one million sq. kilometers per year from 1950-1970, and tripled in the 1980’s and early 1990’s. Reduction in the growth rates during and after the 1990’s reflects a lack of space to grow in, rather than a greater awareness of the ecological impact. Chris Costello and Steve Gaines of the University of California, Santa Barbara have developed a method to gauge the health of fishery stocks and applied it to more than 7000 fisheries. They estimate that the fisheries are gravely depleted and have less than half the biomass they need to maintain their maximum annual yield. They also estimate 2% of fisheries have fully collapsed, with less than a 10th of the historical levels of biomass and that incidents of collapse are rising.

So not only have we run out of places to find fish, but the places we do have are already losing the ability to keep up with our current needs. 

Cressey, D. (2009) Future Fish. Nature 458(26) pp398-400

The world's fisheries are in an even worse state than feared, The Economist