Society and the Environment: Changing Seas

catching fish

Overfishing from higher trophic levels means commercial fishers must harvest from lower trophic levels to meet demand.

Most of the food we eat comes from agriculture and farming, but we also rely on the fishing industry. About 15% of the animal protein consumed in the world comes from fish and other marine and aquatic organisms. But many fish species have been overharvested. The swordfish and cod fisheries of the North Atlantic and the salmon fishery off the northwestern coast of the United States are examples of depleted fisheries. In many parts of the world, sharks are disappearing rapidly because of the demand for shark fin soup. Some fisheries now contain so few fish that harvesting them is not economical. And the size of some of the harvested fish that remain are now smaller because they don’t survive long enough to grow.

Fishing Down the Food Chain
Fish such as sharks, tuna, and cod are top carnivores in ocean food chains and food webs. As populations of these fish have declined, species from lower trophic levels that were once swept back into the sea have become more common in fish markets. Organisms from lower trophic levels such as mullet, squid, and herring, which often are used as bait, now appear on restaurant menus. Also, the high prices for large fish have encouraged fisheries to catch these predators. In 2012, one bluefin tuna weighing almost 273 kg sold for over $700,000! At prices that high, it is economical to keep fishing even after populations are scarce.

Scientists are working to determine what species are most at risk of overfishing and what will happen to ecosystems if overfishing continues. If the food webs of ocean ecosystems are altered too much, the commercial fishing industry will be in trouble so it makes economic sense for fishers to protect the oceans.

Creating Sustainable Fisheries
One aim of environmental science is to determine how fisheries can be managed so that they are sustainable or capable of supplying the same number of fish to be harvested each year. One solution is to establish “no-take” zones. These are areas of the sea where no fishing is permitted. Fish populations grow rapidly in these zones. When a population grows in a “no-take zone,” some organisms leave the zone and become available to fishers. “No-take” zones help populations recover and allow food chains and food webs to remain intact.


  1. Bo H Whitteker says

    Fish is the best meat for humans to eat in my opinion because of the nutritional value that it holds and over fishing creates a problem for the ecosystem the no fish zones will help over time as the fish realize which areas are safe for the. A solution to this would be to open more fish farms for humans to eat and to put fish back into the ocean.

  2. Austin Baker says

    Over fishing is a danger to many aquatic ecosystems. fish species are rapidly declining and the demand for these fish are declining for the time. shark numbers are rapidly declining because of a demand for their fins for food. blue fin tuna are declining but the price for them is increasing drastically. in the end overfishing needs to be stopped to let the fish numbers replenish.

  3. Scientists have recently discovered some of the types of fish that are at risk due to overfishing. We rely on the fishing industry for some of our food, and it is shown that people still fish even if the populations are scarce. The “No-take” zone is a good idea because it allows fish to not be caught until the population has grown big enough and it is okay. This helps people manage their fishing and also helps populations recover to allow the food chains and food webs remain intact.

  4. Brandyn Brewer says

    Over fishing is not a good thing. Lots of people rely on fishing companies and the companies cant do much if other people are over fishing. If it continues the fishing industries will be in big trouble. I think there should be more rules to prevent over fishing and i agree that we need no fishing zones to help.

  5. If the fish population goes down then there will not be an abundent of the fish to keep the sea clean so then the sea will over flow with several different things that can cause harm to the ocean and the animals in it .

  6. Tyler Rigsby says

    I think in order to have the fish populations go back to normal, we need to have bigger zones where there is no fishing allowed. That way the area where there is no fishing the more room they have to re-populate.

  7. Over fishing is a problem that needs to be dealt with. People need to be made aware of the danger aquatic ecosystems are in. Fishing industries rely on fish and over fishing will eventually put these industries out of business. There needs to be more strict rules on fishing zones.

  8. Brandon Hunsaker says

    Over fishing is putting multiple species close to the endangered list. High demand fish species are declining in population very rapidly. There will have to be a law on what may be caught or there will be some species that will leave the earth forever, and it will be humans fault.

  9. Many species are becoming endangered due to over fishing. I think that limiting the amount of fishing allowed will help the numbers go back up to normal. A lot of people rely on fish for food and many people continue to fish when numbers are so low. I think the “No-Take” zone will be very beneficial for these endangered species. I think once numbers are high enough fishing should be allowed.

  10. Cassidy Russell says

    Over fishing is causing many of the oceans species to become endangered. Certain laws should be in place to help those species numbers rise back up. The “no-take zone”, is a good way to help the numbers rise, but more laws should be set in place if we want the animals to thrive and prosper.

  11. Lauren Baird says

    The populations of certain species of fish are becoming endangered due to the overfishing of cheaper fish. If we continue down this path, the food chains and webs will begin to fall apart. The implementation of regulations and “no fishing zones” would stabilize the populations and allow the food chains to be revitalized. More laws should be put in plave, but only until the populations are regulated.

What Do You Think?