Fish have been a food source for humans since the very beginnings of our species. It is the 3rd major source of food for humans, after grain and meat, and in coastal areas, especially Asia and Africa, fish accounts for all animal protein consumed. In the olden days, people used to use small, wooden fishing boats, single fishing poles, and manually use nets to catch fish. Now, however, technological advances have provided us with gasoline-powered fishing ships and mile-long nets to catch as many fish as possible. Human population growth and the popularity of fish delicacies have heavily contributed to this increased demand for fish.
A fishery is a commercially harvestable population of fish within a particular ecological region. Examples include the salmon fishery of Alaska and the tuna fishery of the eastern Pacific Ocean.
Overfishing is defined as catching more fish than the ecosystem is able to naturally reproduce. Fishers are working harder and catching less fish as a result of overfishing. Overfishing causes problems such as resource depletion, the extinction of whole species , and the upset of entire marine and terrestrial ecosystems. By catching too many fish now, we gain food in the short term, but we lose this food source in the future. From a human-centric view, if overfishing continues, one of the largest protein sources will disappear, exacerbating the food shortage crisis. When the fish from a fishery disappear from overfishing, the fishers of that specific fishery lose their jobs.
From a more ecological standpoint, just like what the European sailors did with the dodo bird in the 17th century, we will drive certain species of fish to extinction. This is a very big deal because the extinction and even the decreased population of fish will cause huge imbalances to the ecosystem. Take a typical food chain in the oceans.
By overfishing tuna, for example, we rid a certain ecosystem of a top predator, or level 4 organism. We leave the fish below that in the 3rd level without a major predator. Without this population control mechanism, the level 3 fish thrive and overpopulate. Because these fish also need food, they feed on the level 2 organisms. The increased pressure on the level 2 organisms cause a depopulation. The level 3 fish population, as a result, also decreases. This snowballing effect leaves even more species of fish on the verge of extinction. This also further lowers the amount of fish that we can catch, eat, and sell on the market.