What causes fishing to be unsustainable?
You may have heard the word ’unsustainable’ used in relation to fossil fuels. Coal, oil and gas are non-renewable energy sources — meaning there are limited supplies of them. This means that high rates of extraction of these resources is a process that cannot be continued for very long — it cannot be sustained. Although fish are not considered a non-renewable resource, as they are able to replenish their numbers, humans have made the task of population sustenance increasingly difficult, as we deplete the oceans of individuals faster than they can reproduce.
What makes large-scale fishing an even bigger problem is the issue surrounding bycatch.
What is bycatch?
Bycatch is the unwanted capture of other animals when fishing for particular species. For example, a fishing operation with the aim to catch Yellowfin Tuna also catches a number of Common Dolphins. The dolphins that were caught are referred to as bycatch.
Why is this a problem?
Often, when unwanted species are brought onboard a fishing boat, the simplest option for fishermen is to kill the animal and dispose of it back into the sea. It will not bring them any profit, so they have no reason to keep or save the animal. Because of this, experts estimate that 38 million tonnes of unnecessary individuals are caught annually. That is nearly 50% of the entire annual marine catch.
This has extreme consequences on the oceanic environment. It means that rare and endangered species fall victim to large fishing operations, causing a further decline in their population, and possibly extinction. In turn, this causes a host of other issues, such as biodiversity loss and the disruption of food webs. This can harm the very beginning of the food chain and damage groups such as coral, seaweed, algae and plankton.
Furthermore, the oceans act as carbon sinks, playing a huge role in the preservation of our climate. Any damage to them therefore has a knock-on effect for the rest of the world.
Preventing Bycatch:
Bycatch amounts are influenced significantly by the fishing technique and net used. Therefore, it is possible to adapt the fishing method to decrease the numbers of other species caught.
Types of fishing method:
1) Trolling
This method involves using a longline with many hooks attached to it behind the boat. It is often thought of as a low-bycatch technique, however unwanted fish species are still caught and are tossed back into the ocean, after sustaining injuries to the face from the fishing hooks. Many studies have been carried out to show that nearly all of the fish discarded die from their injuries. One such study on Chinook Salmon in Alaska showed that 85% of the individuals died after they were put back in the sea. Additionally, one in five of the fish caught on these hooks are sharks. Sharks are a vital (and often overlooked) part of many underwater ecosystems; they face a number of threats, and people often use the opportunity of shark bycatch to harvest the animals’ fin for shark-fin soup, and then throwing the animal back into the water. It is also important not to forget about the many seabirds and turtles who get entangled in lines that are littered in the ocean and wash up on the shore.
2) Trawling
This is a destructive, and unfortunately, common fishing practice. Large fishing nets with weights attached are dragged along the seabed, catching everything in their path while simultaneously tearing up the seafloor. It is extremely harmful to many species, including marine plant life and juvenile fish. This has the combined effect of removing vital habitats for fish to raise and protect their young in and capturing all of the young that live there, drastically stunting fish population growth. Trawling for fish accounts for 55% of worldwide bycatch, while shrimp trawling accounts for 27%. Because these figures are so high, the UN demands that fishing boats report their bycatch, however this is unreliable, and it is thought that millions of tonnes have gone unreported in the last 50 years.
3) Traps
Trapping is often used for crustaceans. It is more species-specific than other methods, but that does not mean that it is without flaws. Other species can be trapped in the ropes, lines and pots as the waste is commonly unmanaged and discarded into the ocean. Further, if the traps are dragged along the sea bed, then environmental degradation can occur.
4) Purse Seining
This method is often used with the aim of catching schools of fish. A large net is drawn around the target school and pulled shut as it is taken up to the surface. It has lower bycatch rates than trawling, but larger mammals and sharks are often captured.
5) Gillnet Fishing
These nets work by trapping the fish by their gills, this is an extremely unpleasant method as it means the fish die slowly on the nets. Marine mammals can get caught in the vast netting and drown, while unwanted fish species may also become trapped. The Fransiscana Dolphin has been made endangered by the use of Gillnets in the Atlantic Ocean.
6) Longline Fishing
A long fishing line with over 2000 hooks is extended across the oceans surface, held up by buoys. Bycatch is high, at over 20%. Mammals, such as sea turtles, are often caught by the hooks as they require oxygen from the air and so travel up to the surface. Longline fishing is responsible for the deaths of 50-100 000 seabirds annually.
Is there a better method to prevent bycatch?
Fishing methods that reduce the amount of bycatch are often disregarded by fishing corporations, as they are less efficient and less profitable, requiring more human labour and catching less fish (such as pole and line fishing). This means that finding a better alternative is very difficult. Environmentalists encourage people to avoid fish products, or if they do choose to consume fish then to buy locally caught fish or to catch their own fish to ensure that no other endangered species are caught.
The Grey Area Surrounding ’Dolphin-Safe’ Fish:
Many fish products hold certain labels claiming that their fish are sustainably caught, or are ’dolphin-safe’. Outrage was caused within environmental organisations about the fairly recent exposé of many large fishing corporations that were thought of as ’sustainable’, but were found out to be contributing greatly to the endangerment of many species. For this reason, scientists now disregard the credibility of MSC certified products. This causes the public to be confused and unsure about where their fish is actually sourced, aggravated by the mix of statements by different representing bodies.
Claire Christian, co-author of a major study in the Biological Conservation Journal states:
“MSC’s narrow definition of sustainability is out of step with the general public perception of what that term means.
When MSC labels a swordfish fishery that catches more sharks than swordfish ‘sustainable’, it’s time to re-evaluate its standards.”
While the heads of the fisheries continuously claim that none of these statements are true.
Facts And Figures:
- – 300 000 small whales and dolphins
- – 250 000 loggerhead and leatherback turtles
- – 300 000 seabirds, including 17 albatross species
- In total, 38 million tonnes of bycatch per annum.
