Sustainable fishing is a set of practices that prevents overfishing. It guarantees there will be populations of ocean and freshwater wildlife for the future. The world's oceans and rivers are home to countless species of fish and invertebrates such as crabs, lobsters and shrimp, most of which are consumed as food. For thousands of years, people have fished to feed families and local communities.

Demand for seafood and advances in technology have led to fishing practices that are drastically reducing fish and shellfish populations around the world. Fishers remove more than 77 billion kilograms (170 billion pounds) of wildlife from the sea each year. Scientists fear that continuing to fish at this rate may soon result in a collapse of the world's fisheries. In order to stop this from happening, fishers will need to start using sustainable fishing practices.

Consider the example of the bluefin tuna, which is known for its delicious meat. High demand for this fish has threatened its population. Today, there are only around one-quarter as many spawning bluefin tuna — those releasing eggs — as there were in 1970.

Since about that time, commercial fishers have caught bluefin tuna using purse seining and longlining. Purse seine fishing uses a net to herd fish together and then trap them by pulling the net's drawstring. The net can scoop up many fish at a time. It is typically used to catch schooling fish traveling in large groups or fish that come together to spawn. Longlining is a type of fishing in which a very long line up to 100 kilometers (62 miles) is set and dragged behind a boat. These lines have thousands of baited hooks attached to smaller lines stretching downward.

Both purse seining and longlining can catch hundreds or thousands of fish at a time.

Overfishing

For fishers, catching so many fish at once is very profitable. However, over time this type of fishing leaves few fish of a particular species left in the ocean. If a fish population becomes too small, it cannot easily replenish itself, or grow back to or close to its original size. Fish populations replenish through reproduction, or the birth of new fish.

Taking wildlife from the sea faster than populations can reproduce is known as overfishing. Purse seining, longlining and many other types of fishing can also result in a lot of bycatch, or the catching of species that weren't purposely targeted. Longlines intended to catch bluefin tuna (Thunnus thynnus), for instance, also catch other fish, such as swordfish (Xiphias gladius). In addition, they can trap birds and sea turtles.

Chilean seabass (Dissostichus eleginoides) is another fish species that has been overfished. In the 1990s, this fish became extremely popular in restaurants, causing an increase in demand. Seabass is native to the South Pacific and South Atlantic Oceans. It is typically caught by longline in international waters. Fishing in international waters is regulated by international agreements, which are very difficult to enforce. Illegal fishing of seabass — in this case catching many more than was allowed — became widespread. Over time, the number of seabass caught and the average size of the fish decreased, leading to even higher prices and greater motivation for illegal fishing. Chilean seabass is a long-lived, slow-growing fish. Smaller seabass are likely younger, and may not have spawned yet. As fishers caught smaller seabass, healthy replenishment of the population became unlikely, because more and more young fish never grew old enough to spawn.

Today, import of Chilean seabass into the United States is highly regulated. However, illegal fishing still continues.

Overfishing also occurs with freshwater fish. One example is the beluga sturgeon (Huso huso), a large, slow-growing fish. Beluga sturgeon can grow up to 4.5 meters (15 feet) and 1,135 kilograms (2,500 pounds). They take about 20 years to reach maturity, at which point females release their eggs (called roe), although they only do so every three to four years. Beluga sturgeon are best known for roe — also known as caviar. In fact, Caspian Sea sturgeon are the source of about 90 percent of the world's caviar. The fish are slow-moving and easy prey for fishers. When their eggs are harvested, the fish cannot maintain their populations.

Rules regulate the caviar harvest and imports in countries worldwide, but illegal fishing and international demand are huge threats. The fish's population continues to decline.

Sustainable Fishing Practices

There are ways to fish sustainably. Such practices allow us to enjoy seafood while ensuring that populations remain for the future. In many traditional cultures, people have fished sustainably for thousands of years. Today's sustainable fishing practices reflect some lessons learned from these cultures.

In the Philippines, for example, the Tagbanua people have traditionally used fishing practices that maintain fish populations. They continue to follow these practices today. Tagbanuas fish for specific species only during certain times of the year, allowing fish stocks to replenish themselves. They set aside certain areas as protected spots in which fishing is forbidden. When they do fish, these traditional fishers primarily use hook-and-line methods. They catch only what they need to feed themselves and their communities.

If you have ever gone fishing, chances are you used a rod and reel. Rod-and-reel fishing is a modern version of traditional hook-and-line. Rods and reels come in different shapes and sizes, allowing recreational and commercial fishers to target a wide variety of fish species. Rod-and-reel fishing results in less bycatch because non-targeted species can be released immediately. Additionally, only one fish is caught at a time, preventing overfishing. For commercial fishers, rod-and-reel fishing is a more sustainable alternative to longlining.

Another way to prevent overfishing and bycatch is to simply stop eating fish and other seafood. Dr. Sylvia Earle, a famous and well-respected marine scientist, has taken that step. She suggests people need to take a break from eating seafood until we learn to maintain healthy fish populations.

"I personally have stopped eating seafood," Earle says. "I know too much. I know that every fish counts at this point." Fish, she says, are critical to maintaining the health of ocean systems, which in turn "make the planet work."

Those of us who continue to eat fish should try to choose seafood from well-managed, sustainable fisheries. To do so, we should educate ourselves about where our fish comes from and how it is caught. Resources such as the Seafood Decision Guide can help us make the best choices for our ocean's future.