Trawl fishing is one of the most destructive fishing methods, yet is still commercially allowed to continue world wide. There are some limitations in different countries, such as certain areas being banned, or certain times of year in certain places.
Bottom trawling affects the seabed, the net drags along the bottom stirring up the sediment, moving sessile species, turning over large rocks, and destroying habitats such as coral reefs, seagrass and seaweed beds. This can modify the ecosystem structure meaning a shift towards more opportunistic organisms which take advantage of the change in the seabed.
The re-suspension of sediment can sometime be seen from space, these huge plumes put chemical and other particles back into the water column. The amount of particles re-suspended per year by bottom trawling is thought to equal the amount introduced to the ocean by rivers. These chemicals can return to our food chain by first being absorbed by plankton. Light can be blocked by the increased turbidity, carbon dioxide is released causing oxygen deficient ocean dead zones and harmful algal blooms.
A recent study has shown trawl fishing can release more carbon dioxide back into the oceans and the atmosphere than air travel did at pre-pandemic levels.
Pelagic trawl fishing is thought to be less harmful to the environment, however is still not a selective method of fishing. It is thought to be one of the major causes of by-catch, retaining huge volumes of non-target species including sharks, turtles and cetaceans. The size of the mesh affects what is retained in the net. Juveniles of many different species are often retained. Pelagic trawl fishing is thought to be a major cause of cetacean deaths. Shrimp trawling is one of the worst methods, thought to be responsible for the highest amount of by-catch. In the UK there are 5 most common types of seafood eaten: cod, haddock, tuna, salmon and prawns. Trawling catches over 77 different species and most of these are discarded. Most fish stocks around the UK are over fished, including a number of species which are classified as endangered.
The only way I eat fish now is if I have caught it myself, which we did a few times crossing the Atlantic. It meant we could go from Ocean to plate within minutes, giving us the freshest fish possible. It also meant we could return any fish that was too small.
There are ways you can choose fish yourself to eat which is better for the environment. You can use the MCS good fish guide or the MSC sustainable fish to eat list to guide you when shopping. My recommendation would be to try and go to a local fishmonger and look for freshness in the whole fish, e.g glassy clear eyes, a good smell, firmness to the flesh. If you are uncomfortable with cutting the fish up yourself ask the fishmonger to do it in front of you. Unfortunately often in supermarkets pre-packaged fish can be mis-sold, e.g labelling something as white fish is nondescript and may even be shark being sold.
