Destructive fishing practices are those which have an impact on the wider aquatic environment. Dictionary definition of destructive fishing is "to reduce to a useless form, to spoil completely; to put out of existence; to obliterate, wipe out, annihilate, demolish, devastate, tear down, raze". Destructive fishing and over-fishing have led to the collapse of some very important fisheries and fishing communities.
Though under-water species live long lives, they reproduce slowly. Some species can live for more than a century but take decades to reach sexual maturity. They are mostly found on seamounts and in deep-water coral reefs.
Why should I be aware of this?
Fishing is a consumer driven industry as one out of five people worldwide depend on it as a primary source of protein. As destructive fishing threatens the food supply to millions of people, consumers need to make choices to help support sustainable fishing methods. Commercial fishing is carried out through a variety of methods that employ different kinds of gear. Some methods are environmentally sound and some are not. Information here helps discern the good from the bad and the ugly. It can be used to make sound environmental consumer decisions about the fish you eat.
Destructive fishing and environment
Fishing is the most environmentally destructive of all meat industries. Today’s fishing technologies fishing ships stay out on the water for months, using technology such as sonar tracking to hunt down schools of fish. The non-target animals are left to die, leaving environmental devastation. Fishing boats when they are out on water use methods such as bottom trawling and long-lining which have stripped millions of miles of ocean and pushed some marine species to extinction.
Bottom trawling, involves dragging nets larger than football fields along thousands of miles of ocean floor, and other aggressive commercial-fishing practices are wiping out entire underwater ecosystems and pushing our oceans to the brink of environmental collapse.
All about destructive fishing
There are some methods of fishing, such as drift nets or gill nets, which destroy or damage the very seafloor habitats where fishes and many other seafloor animals reside. They end up catching large amounts of bycatch – fish, sea turtles, seabirds and marine mammals - that are unintentionally caught and often incidentally killed in fishing operations.
A large numbers of seabirds get hooked in longline fishing and also pose a real threat to sea turtles, sharks and mammals. There are high rates of by-catch in trawling for shrimp - up to 9 pounds of non-target marine life can be caught for every pound of shrimp. Once caught they are dumped back into the ocean dead or dying.
Destructive fishing equipment include bottom trawls which are large nets used to catch groundfish and other commercially targeted fish and crustacean species. Considered the most destructive fishing gear, bottom trawls directly threaten species richness and biodiversity. They, in the process also catch a number of unmarketable species of fish which are discarded and left to die.
Habitat created by deep sea corals and sponges, several of which are 100 years old, are destroyed by bottom trawls every time they pass.
Bottom trawling has come under severe fire from environmental groups who have called for UN moratorium on this practice. Conservationists feel that the small amount of fish caught in bottom trawling is out of proportion to the damage it causes.
These are baited hooks on lines up to 80 miles long, with each containing more than several thousand hooks at a time. They are used to catch swordfish, tuna, sharks, birds, and turtles. Longline hooks are estimated to kill 180,000 birds worldwide every year, sending many of them on the brink of extinction.
A large number of the endangered wandering albatross population is killed each year by longlines. As a result today 21 albatross species are threatened as against three in 1996. Longline has also sent a large number of petrel species on the brink of extinction.
Sharks, which have slow growth and reproductive rates, are also vulnerable to overfishing, especially longline fishing. In 1998, 60,857 sharks were killed in Hawaiian longline fisheries.
Poisons and Explosives
The economic losses for the local and wider society caused by the use of poisons and explosives far outweigh the short-term, individual gains made by the users of these destructive methods.
Poisons: Poisons, such as cyanide or pesticides, are widely used in both marine and freshwater fishing - especially in coral reefs and coastal lagoon fisheries. Inexpensive cyanide used in the jewellery industry and gold mining can be easily obtained for this purpose. Poisons are used for killing or stunning the fish indiscriminately. They are then collected by divers. The poisons kill also other organisms from the ecosystem, including the coral reef-building organisms.
Explosives: Also known as blast fishing, explosives have been used in fishing for centuries. Following explosions recolonization of damaged habitats in coral reefs is very slow and complete recovery may take several decades. The explosion not only kills both the target fish and the accompanying fauna but can also humans by errors of manipulation. Commercial explosives, which are often obtained from mining or construction activities, can have very serious consequences for the resources, the environment and, unfortunately, sometimes also for the users themselves.
The increasing popularity of Scuba diving, which has become increasingly popular, has put more strain on coral reefs around the world. Divers coming in contact with fragile corals break them or damage their fragile tissue surface. This leaves them open to bacterial attack and disease. Each time an anchor is dropped, 4-6 m2 of the reef surface is destroyed.
Muroami netting is a dangerous fishing practice that has led to extensive coral reef deterioration in Southeast Asia. Fishermen use a combination of nets that are weighted and decorated with brightly colored plastic strips with pounding devices in order to startle and herd reef fish. The pounding devices are usually large stones on ropes or cement attached to a crane fitted to the fishing vessel. The weights are lifted and dropped repeatedly along the reef, breaking live coral along the way. In many counties that use this practice, as many as 300 young boys, 10 to 15 years old, are used to set the nets and bang on the coral. The practice was banned in the Philippines in the 1980s, but continues illegally in some places.
Seal population is exploding and a cull is necessary
In countries like Canada, the government often defends commercial seal hunt on account of harp seal population tripling over the last 3 decades. However, what is glossed over is the fact that over-hunting in the 1950s and '60s had reduced the population by about two-thirds. The 1980s brought a respite with a sharp decline in hunting levels allowing the population to rebuild, but presently kill levels match up to and exceed the 1950s and '60s trend. Moreover, climate change is making things very difficult. Apart from the usual natural predators - sharks, whales and polar bears, reducing ice covers are taking away natural breeding and nursing grounds, exposing young pups to devastating rates of early deaths.
How can we help
- Go for local, organic and sustainably farmed fish.
- Join movements like the Slow Fish Movement, where you can as a collective body make yourself heard.
What is being done
- Leatherback sea turtle most threatened -- In an effort to halt wasteful fishing methods, 405 scientists from 47 nations -along with 100 conservation, animal welfare and other nonprofit groups - signed open letters to the United Nations, urging governments and fisheries managers in the United States and abroad to heed the worsening crisis of global fisheries.
The scientists are of the opinion that the Pacific leatherback sea turtle is the most threatened among the marine species by longlining and gill netting. In their estimation there are now less than 5,000 nesting female leatherbacks left in the Pacific Ocean - down from 91,000 in 1980, a decline of 95 percent.
News and Current Research
- Global trade in tiger shrimp threatens environment 
- Destructive fishing practices
- CONSERVATION SCIENCE INSTITUTE
- Destructive fishing
- FAO - Fisheries andAquaculture Department