scienceyoucanlove:

Overfishing—catching fish faster than they can reproduce—is an urgent and devastating issue, and may be the single biggest threat to ocean ecosystems. Today, 85 percent of the world’s fisheries are either fully exploited, overexploited or have collapsed. The global fishing fleet is operating at 2.5 times the sustainable level—there are simply too many boats chasing a dwindling number of fish.

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, of the 307 shark species assessed by the International Union for Conservation of Nature, 50 are listed as vulnerable, endangered or critically endangered. Several species of rockfish—a group of Northeast Pacific fish also known as snapper that can live to be over 100 years old—were severely depleted by years of overfishing. Despite new fishing restrictions, 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 few decades from high-level predators such as tuna and cod, to species lower in the food web, like crabs, sardines and squid—a phenomenon known as “fishing down the food web.” Since these species are often important prey for other fish, as well as seabirds and marine mammals, their removal impacts species throughout the ecosystem. 

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,