[show abstract][hide abstract] ABSTRACT: Up to one-third of commercial fishery stocks may be overfished at present. By analyzing catch trends and applying an empirical relationship derived from stock assessments, this article tracks the geographic spread of overfishing at the country level in terms of lost catch and lost revenue, from the start of industrialized fishing in 1950–2004. The results tell a cautionary tale of serial depletion to meet the ever-rising demand for fish. Examining country losses with respect to fishery management reveals that overcapacity and excess fishing effort are widespread, but also that recent trends towards sustainability can stabilize or reverse losses (e.g. for Norway, Iceland, the US, Canada, Australia, and New Zealand). Global trade effectively masks the successive depletion of stocks, so that without decisive action to reduce fishing effort, many more stocks will suffer and undernourishment impacts for the major exporting, food-deficit nations will only magnify.
[show abstract][hide abstract] ABSTRACT: As human impacts to the environment accelerate, disparities in the distribution of damages between rich and poor nations mount. Globally, environmental change is dramatically affecting the flow of ecosystem services, but the distribution of ecological damages and their driving forces has not been estimated. Here, we conservatively estimate the environmental costs of human activities over 1961-2000 in six major categories (climate change, stratospheric ozone depletion, agricultural intensification and expansion, deforestation, overfishing, and mangrove conversion), quantitatively connecting costs borne by poor, middle-income, and rich nations to specific activities by each of these groups. Adjusting impact valuations for different standards of living across the groups as commonly practiced, we find striking imbalances. Climate change and ozone depletion impacts predicted for low-income nations have been overwhelmingly driven by emissions from the other two groups, a pattern also observed for overfishing damages indirectly driven by the consumption of fishery products. Indeed, through disproportionate emissions of greenhouse gases alone, the rich group may have imposed climate damages on the poor group greater than the latter's current foreign debt. Our analysis provides prima facie evidence for an uneven distribution pattern of damages across income groups. Moreover, our estimates of each group's share in various damaging activities are independent from controversies in environmental valuation methods. In a world increasingly connected ecologically and economically, our analysis is thus an early step toward reframing issues of environmental responsibility, development, and globalization in accordance with ecological costs.
Proceedings of the National Academy of Sciences 03/2008; 105(5):1768-73. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although an ecosystem's response to biodiversity loss depends on the order in which species are lost, the extinction sequences generally used to explore such responses in food webs have been ecologically unrealistic. We investigate how several extinction orders affect the minimum number of secondary extinctions expected within pelagic food webs from 34 temperate freshwater lakes. An ecologically plausible extinction order is derived from the geographically nested pattern of species composition among the lakes and is corroborated by species' pH tolerances. Simulations suggest that lake communities are remarkably robust to this realistic extinction order and highly sensitive to the reverse sequence of species loss. This sensitivity is not well explained by the known sensitivity of networks to the loss of highly connected species but appears to be better explained by our observation that trophic specialists preferentially consume widely distributed species at low risk of extinction. Our results highlight an important aspect of community organization that may help to maintain biodiversity amidst changing environments.
[show abstract][hide abstract] ABSTRACT: Excess fishing capacity and the growth in global demand for fishery products have made overfishing ubiquitous in the world’s
oceans. Here we describe the potential catch losses due to unsustainable fishing in all countries’ exclusive economic zones
(EEZs) and on the high seas over 1950–2004. To do so, we relied upon catch and price statistics from the Sea Around Us Project as well as an empirical relationship we derived from species stock assessments by the U.S. National Oceanic and Atmospheric
Administration. In 2000 alone, estimated global catch losses amounted to 7–36% of the actual tonnage landed that year, resulting
in a landed value loss of between 6.4 and 36 billion (in 2004 constant US6.4 and 36 billion (in 2004 constant US). From 1950–2004, 36–53% of commercial species
in 55–66% of EEZs may have been overfished. Referring to a species-level database of intrinsic vulnerability (V) based on life-history traits, it appears that susceptible species were depleted quickly and serially, with the average V of potential catch losses declining at a similar rate to that of actual landings. The three continental regions to incur
greatest losses by mass were Europe, North America, and Asia—forming a geographic progression in time. But low-income and
small island nations, heavily dependent on marine resources for protein, were impacted most profoundly. Our analysis shows
that without the inexorable march of overfishing, ~20 million people worldwide could have averted undernourishment in 2000.
For the same year, total catch in the waters of low-income food deficit nations might have been up to 17% greater than the
tonnage actually landed there. The situation may be worst for Africa, which in our analysis registered losses of about 9–49%
of its actual catches by mass in year 2000, thus seriously threatening progress towards the UN Millennium Development Goals.
KeywordsCatch loss-Food security-Undernourishment-Landed values