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Measuring the biological sustainability of marine fisheries: property rights, politics, and science

  • Author(s): Michael DeAlessi
  • et al.

While nearly everyone favors sustainability, few agree on what the term actually means. In the case of marine fisheries, what first appears simple – exploiting species at a level that does not diminish their productivity in the future – is confounded by the possible inclusion of social, cultural, and economic notions of sustainability, as well as the effects of fishing practices on the wider ecology (that is, on both non-target species and habitats) of the seas. These approaches are all important, but this paper will focus on measuring the biological sustainability

of targeted species, which must precede (but certainly not preclude) all other measures of sustainability. While determining what is sustainable is tricky, it is not difficult to find examples of biologically unsustainable fisheries.

From the dramatic collapse of the once prolific cod fisheries of New England and Eastern Canada to the decline of subsistence fisheries throughout the developing

world, marine fisheries are a classic case where the sustainable development of a resource has been the exception

rather than the rule. According to the Food and Agriculture Organization of the United Nations (FAO 2007), worldwide marine fish catches have declined over the last ten years and most marine capture fisheries are now either depleted or hovering at the brink of overexploitation.

In the United States, the National Marine Fisheries Service (NMFS 2002) reports that almost one-third of U.S. fish stocks are overfished, or that 75% of U.S. commercial fish stocks are either overexploited or fully exploited. Some academics have suggested that the problem is even worse, estimating in the journal Science that since the advent of industrial fishing more than 90% of large predatory fish have been removed from the world’s oceans (Worm and Myers 2003). Subsequently, Nature published one extrapolation of current trends in loss of diversity and ecosystem function that predicted a global collapse of all commercial fisheries by 2048 (Worm et al 2006).

This research succeeded admirably in raising eyebrows,

as well as criticism. Fisheries scientist Ray Hilborn (2007a) depicts the 2048 prediction as “ridiculed by most fisheries scientists”, and describes similar studies, including the precipitous decline of large predatory fish, as “either outright wrong or serious distortions of reality” (citing, for example, Hampton et al 2005). In addition, pronouncements from agencies such as FAO that seem dire at first glance – such as listing the majority of fisheries

as either fully or overexploited – belie the fact that for many countries, full exploitation is the stated goal of fisheries policy. The list also says nothing about whether overfished stocks are recovering or not. Finally, Hilborn (2003) notes that in the U.S. context, most fisheries classified

as overfished are still producing significant catches, so that even if they were pessimistically producing only half of their potential yield, “U.S. production would [still] be at 84% of maximum” – which sounds very different

than 75% overfished or fully exploited.

The issue is not whether depletion is a widespread problem, but just how bad things have become, and what might be done to fix the problem. Part of this difference

of opinion stems from the fact that fisheries can be managed for economic, biological, or social objectives.

Not only are the criteria for success different in each of these cases, but also within similar fields, as is the case with fisheries scientists such as Hilborn and marine ecologists such as Myers and Worm. That social scientists are even less likely to agree on measures, let alone desired outcomes, only highlights the complexity of the issue.

Measuring performance is crucial to understanding which fisheries are being successfully managed. This paper will focus on biological sustainability, as it lies at the heart of the sustainable development of marine resources. It will address the ways that institutional and political causes of depletion and the uncertain nature of fisheries science have undermined measures of biological

Measuring the biological sustainability of marine fisheries: property rights, politics, and science

Michael De Alessi*

* Michael De Alessi, Department of Environmental Science, Policy, and Management at UC Berkeley,

and a Senior Fellow at the Reason Foundation in Los Angeles.

Email: (replace =a= with @)


Measuring the biological sustainability of marine fisheries

sustainability; explore ways that success may be better measured; and conclude with a proposal for a new approach to measuring biological sustainability.

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