Overfishing is when a particular type of fish is harvested so often and in such great numbers that the population of that fish is severely depleted, resulting in endangerment and potential extinction. This generally is the result of commercial, rather than recreational, fishing. Overfishing has implications well beyond marine life; it affects the human food supply, the fishing industry, and the environment.
The worldwide fishing industry may use many different types of technology in order to locate and catch fish. Some fishing liners can remain at sea for weeks and can freeze and process the fish they catch on board. This means that they only have to come to port when their stores are full. Fishermen on such ships are able to harvest more fish in a shorter period of time. The fishing industry can experience greater catches this way, and as a result more species can be overfished.
As the fish are reduced in number, fishermen may use smaller nets trying to catch smaller fish. The result is that younger fish are often caught. Catching young fish can be problematic if they are caught before they are able to breed and contribute to replenishing the population. The use of nets can also lead to bycatching, which is the trapping of non-target species. For example, porpoises can get caught in salmon nets, and dolphins can get caught in tuna nets.
Overfishing can also affect species that fishermen never catch. If one type of fish is eliminated, the entire ecosystem can collapse. For example, cod fish prey on herring. If a fisherman harvests all the herring in a particular area, then the cod starve. Overfishing can also affect other non-marine animals, such as birds, that rely on fish for food.
Not only can overfishing have an impact on marine life, it can also have an impact on human life. An example of this is an incident that occurred in Newfoundland, Canada in 1992. At the start of the fishing season, the cod that usually frequented the water did not appear. Many of the people who depended on catching the cod lost their livelihood.
The problem of overfishing is one that could result in serious economic and environmental implications for the world at large. Governments worldwide have conducted studies and enacted laws to reduce or outlaw overfishing. Advocate groups exist that encourage consumers to reduce the demand for overfished species by purchasing fish that are harvested in a sustainable manner.