Large Fish are First to Go

Large fish, those that live a long time and those that are slow to reproduce are among the most vulnerable. Unfortunately, this includes some of our favorite seafoods. For instance 17 percent of all shark species—slow growing, slow reproducing fish—are endangered or threatened. Rockfish, a west coast species that can live to be over 100 years old, were severely depleted by years of overfishing. Emergency closure of the fishery is a step in the right direction, but it will be decades before these long-lived fish begin to recover.

Fishing Down the Food Web

When one kind of fish is no longer plentiful, fishermen may move on to new species. Scientists have documented a gradual transition in fisheries landings over the last 30 years from high-level predators such as tuna and cod, to species lower in the food web, like crabs, sardines and squid. Since these species are important prey for other fish as well as seabirds and marine mammals, their removal impacts species throughout the ecosystem. Known as "fishing down the food web," this trend can spell trouble for the remaining high-level fish, who find increased competition for preferred prey.

Finding a Solution for Fishermen

The ocean ecosystem—and the food on our tables—aren't the only things affected by overfishing. Along the way, it becomes more and more difficult for fishermen to make a living. Many fisheries have already suffered. Some—like New England cod—have already "collapsed," meaning the population is at 10 percent or less of their historic levels, a point at which recovery may be impossible. When this happens, coastal economies can be devastated.