- As fish stocks decrease globally, fishing methods have become increasingly extreme.
- Destructive fishing practices refers to any type of fishing technique that destroys fish habitat and devastates the marine environment including bottom trawling, bycatch, the use of poison and explosives and ghost fishing.
- These types of exploitive fishing destroy habitat where reef animals live and breed and further disrupts the ecological food chain.
- Destructive fishing practices inhibit the growth of new corals, while the sediment left behind from blast fishing makes it difficult for juvenile corals to settle and grow.
- A loss in the number of fish due to habitat destruction can lead to fewer fish and reduces the ability of fish to reproduce. A significant number of non-targeted species are also killed through destructive fishing.
- Scientists estimate that 56 percent of the coral reefs in Southeast Asia are currently at risk from destructive fishing.
- One of the most harmful techniques is bottom trawling, an industrial method in which enormous nets are dragged along the sea floor, decimating everything in their path from fish to marine mammals to ancient coral.
- Marine species, many which are critically endangered, are caught and then thrown back into the sea, often already dead or dying. This colossal waste, known as discards, can reach up to 80% or even 90% of the total catch.
- Large areas of the seabed, the habitat where fish find food and shelter, are crushed and flattened. The biggest nets used for bottom trawling can leave scars on the seabed more than 4 kilometers long.
- Seabed ecosystems contain abundant biodiversity and the damage caused by bottom trawling can be permanent. Bottom trawling often churns up toxic sediment, creating turbid water where marine animals would normally live, rest and hide from predators.
- Often used by commercial fleets in the high seas, this practice is very often left unregulated which is largely due to the lack of global fisheries management.
- Deep-water fish grow very slowly and have a long life expectancy and a late reproductive age. As a result, they are particularly vulnerable to disturbances in their environment caused by bottom trawling.
- Bycatch is one of the most devastating aspects of ocean depletion. Bycatch refers to all the forms of marine life caught unintentionally while catching other fish.
- Modern fishing vessels catch staggering amounts of unwanted fish and other marine life. It's estimated that 8 to 25 percent of the total global catch is discarded, cast overboard either dead or dying. Approximately 27 million tonnes of fish are thrown out each year.
- Every year, an estimated 300,000 whales, dolphins and porpoises die entangled in fishing nets, along with thousands of critically-endangered sea turtles.
- Long-line fisheries also kill huge numbers of seabirds. Over 100,000 Albatrosses die this way every year, and many species are endangered as a result of bycatch.
- All modern forms of commercial fishing produce bycatch, but shrimp trawling is by far the most destructive: it is responsible for a third of the world's bycatch, while producing only 2% of all seafood.
- Recent studies estimate that bycatch represents 40% of all global marine catches, and that in many cases the fish discarded are juveniles, thus posing serious threats to species to reproduction.
- Beyond the pressure on marine species, bycatch represents a depletion of food source for marine predators, thus effecting the overall delicate food chain balance.
- Poison fishing commonly referred to as “cyanide fishing,” is a highly destructive fishing method used to capture live fish for the aquarium and food trades.
- The use of poison to kill fish is very common, in both fresh and salt water, including many coral reefs systems worldwide. This method includes squirting cyanide or other poisons into reef crevices to stun fish, making them easy to catch.
- The use of poison to catch fish kills all the organisms in the ecosystem, including the corals that help form the reef.
- Sodium cyanide and bleach are the two most commonly used poisons. The impact of these poisons on the reef ranges from coral bleaching to death.
- Cyanide fishing is used on the now-devastated reefs of the Philippines – where an estimated 65 tons of cyanide are poured into the sea each year.
- The use of explosives for blast fishing is also on the rise globally. Explosions can produce very large craters, devastating between 10 and 20 square meters of the sea floor.
- Dynamite fishing or “blast” fishing, is often carried out with bombs created from locally available materials. Fish are killed by the shock waves from the blast and are then skimmed off the surface or collected from the bottom by divers.
- Dynamite fishing not only target fish, but all the other surrounding fauna, flora and marine species. In coral reefs, reconstruction of the damaged habitats can take decades.
- These explosions not only kill large numbers of fish and other marine organisms in the vicinity, but they also destroy the physical structure of coral reefs.
- On average, a 1-kilogram (35 ounce) beer bottle bomb can leave a crater of approximately 1 to 2 meters in diameter, killing 50 to 80 percent of the coral in that area.
- It can take several hundred years for a coral reef to rebuild after the use of explosives. Although illegal, dynamite fishing is practiced in up to 30 countries in Southeast Asia and Oceania and is also common in Eastern Africa.
- Ghost fishing is the result of nets and other fishing materials that are accidentally or intentionally abandoned in the sea.
- These nets continue to senselessly trap fish and shellfish and even large marine mammals, which die of exhaustion or suffocation after struggling to get to the surface to breathe.
- The problem of abandoned or lost equipment has been amplified by increased fishing activity and the introduction of nets and line made from long-lasting synthetic material.