ABSTRACT
Until late in the twentieth century, many people thought that the world’s oceans were so big and fish so numerous that human activity could never have any substantial impact. What is clear now is that people have profoundly affected the world’s oceans both directly and indirectly. This chapter focuses on how people’s efforts to capture fish and shellfish have caused rapid declines all over the world in the abundance of many species and in the mix of species. For example, fisheries scientists recently estimated that over the past 50 years the global biomass of large predatory fish – such as tuna and swordfish – has declined by 90 percent, and that the diversity of these fish has declined 10-50 percent (Myers and Worm 2003; Worm et al. 2005). The decline of fish populations is often particularly hard on poor coastal communities – in both the global North and South – where many people depend on fishing (and fishing related industries, such as boat building and fish processing) for food and employment. The crisis of overfishing, then, has both environmental and socio-economic dimensions: overfishing is a problem for fish, their ecosystems, and people that depend on them.
