Blast fishing or dynamite fishing is the practice of using explosives to stun or kill schools of fish for easy collection. This often illegal practice can be extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat (such as coral reefs) that supports the fish. The frequently improvised nature of the explosives used also means danger for the fishermen as well, with accidents and injuries.
Although outlawed, the practice remains widespread in Southeast Asia, as well as in the Aegean Sea, and coastal Africa. In the Philippines, where the practice has been well-documented, blast fishing was known prior to World War I, as this activity is mentioned by Ernst Jünger in his book Storm of Steel. One 1999 report estimated that some 70,000 fishermen (12% of the Philippines' total fishermen) engaged in the practice.
Extensive hard-to-patrol coastlines, the lure of lucrative, easy catches, and in some cases outright apathy or corruption on the part of local officials make enforcement of blast fishing bans an ongoing challenge for authorities.
Commercial dynamite or, more commonly, homemade bombs constructed using a glass bottle with layers of powdered potassium nitrate and pebbles or an ammonium nitrate and kerosene mixture are often employed. Such devices, though, may explode prematurely without warning, and have been known to injure or kill the person using them, or innocent bystanders.
Underwater shock waves produced by the explosion stun the fish and cause their swim bladders to rupture. This rupturing causes an abrupt loss of buoyancy; a small number of fish float to the surface, but most sink to the sea floor. The explosions indiscriminately kill large numbers of fish and other marine organisms in the vicinity and can damage or destroy the physical environment, including extensive damage to coral reefs.
Impact on coral reefs
Researchers believe that destructive fishing practices like blast fishing are one of the biggest threats to the coral reef ecosystems. Blown up coral reefs are no more than rubble fields. The long-term impact associated with blast fishing is that there is no natural recovery of the reefs. Coral reefs are less likely to recover from constant disturbance such as blast fishing than from small disturbance that does not change the physical environment. Blast fishing destroys the calcium carbonate coral skeletons and is one of the continual disruptions of coral reefs. In the Indo-Pacific, the practice of blast fishing is a main cause of coral reef degradation. As a result, weakened rubble fields are formed and fish habitat is reduced.
The damaged coral reefs from blast fishing lead to instant declines in fish species wealth and quantity. Explosives used in blast fishing not only kill fish but also destroy coral skeletons, creating unbalanced coral rubble. The elimination of the fish also eliminates the resilience of the coral reefs to climate change, further hindering their recovery. Single blasts cause reefs to recover over 5–10 years, while widespread blasting, as often practiced, transforms these biodiverse ecosystems into continuous unstable rubble.
In Tanzania, one of the few methods to help manage blast fishing is a joint approach between fisheries officers and village committees. Working together, they help the enforcement agencies recognize offenders by patrolling the sea as well as providing information collected in the local villages. As a result, this has assisted the enforcement agencies to reduce the occurrence of fish blasting from an average of 8 per day to zero. It has also provided sustainable funding to continue the efficient patrols, a certified planning institution, and suitable training and information to prosecutors and judges.
Similar patrols employed in Indonesia and Philippines have reduced the amount of blast fishing occurrences there. Based on dialogue with stakeholder groups in Southeast Asia and people of Tanzania and Philippines, it is evident that firmer enforcement is an effective strategy in managing blast fishing. Many countries have laws regarding blast fishing, but they are not fully implemented. Effective management of Marine Protected Areas (MPAs) is key in the patrolling of illegal fishing areas.
Besides patrols, the restricting or even banning of the sale of ammonium nitrate also makes it much more difficult to produce the explosives that are needed for blast fishing. Another approach is not to restrict or ban the sale of ammonium nitrate, but instead log the people buying large quantities thereof.
Blast detection system
This method involves a triangulation system of hydrophones one meter apart that is capable of detecting blast events and at the same time eliminating other sources of underwater noise. The goal of the system is to improve and assist the effectiveness of fisheries patrol. Based on tests performed in Malaysia from 7 to 15 July 2002, a total of 13 blasts were recorded with a directional uncertainty of 0.2°. An electronic compass would limit the bearing uncertainty to 0.2° while correcting for the local magnetic effects of ferrous metals, therefore making sure the precision of the system is high.
Similar triangulation systems of hydrophones can potentially locate single blast events within 30 m at a range of 10 km. The detector system can be mounted on a patrol boat to help locate a probable range of blasts. Two or more patrol boats would permit accurate triangulation of blast events. Such a method is also beneficial to enforcement agencies, as it offers stronger evidence to support convictions related to blast fishing.
Blast fishing in Indonesia has been around for over 50 years and continues to transform its one-of-a-kind coral reefs into desolate gray moonscapes, as fishermen continue to use explosives or cyanide to kill or stun their prey. Dive operators and conservationists say Indonesia is not doing enough to protect the waters off the Komodo Islands. They say enforcement declined following the exit of a U.S.-based conservation group that helped fight destructive fishing practices. Coral Gardens that were among Asia's most spectacular dive sites, were the latest victim of bomb blasting despite being located inside the Komodo National Park, a 500,000-acre reserve and U.N. World Heritage Site. The use of bombs made with kerosene and fertilizer is very popular in the region. While previously Komodo was relatively protected by a cooperative undertaking with CI (Conservation International) since the Indonesian government has assumed responsibility for park protection, there has been an upsurge in bombing. During a recent visit to Crystal Boommie, it was found to be 60% destroyed, with freshly overturned coral tables proving recent bombing. In the market in the city of Makassar, an estimated 10 to 40 percent of the fish are caught in this manner. The local fishermen find the technique to be easier and more productive than traditional methods. The goal for the country has been to implement stricter polices and fisheries management programs to limit the killing of the fish as well as the destruction to the marine ecosystem. Forty years ago, blast fishing was practiced with dynamite which was in plentiful supply after World War II. Today, fishermen mostly use homemade bombs that are made from bottles filled with an explosive mixture; weights are also added to make the bottle sink faster underwater. After the bomb explodes, the fish killed or stunned by the shock wave from the explosion are collected.
A 1987 study concluded that blast fishing was then very widespread in the Philippines, estimating that 25% of all municipal fish landings (equivalent to 250,000 metric tons per year) were from blast fishing. Most of the blast fishing is however done in the south, near Palawan and the south China Sea. A study conducted in 2002 reported that destructive fishing methods had caused the degradation of about 70% of Philippine coral reefs and reduced annual fisheries production by about 177,500 metric tons in the 1990s.
In 2010, mayor Nino Rey Boniel of Bien Unido town in the province of Bohol, Philippines, built an underwater grotto along the Danajon reef which deteriorated due to excessive dynamite and cyanide use. Through the help of Sea Knights and Boholano divers, two 14-foot statues of Mother Mary and Santo Nino (Spanish for Holy Child) were placed on 8 September and 18 October 2010 respectively, 60 feet below sea level in order to discourage fishermen from using illegal and destructive methods in fishing and hopefully remind everyone that the sea and its inhabitants are gifts from God that deserves to be treasured and taken care of.
In 2012, the director of the Philippine Bureau of Fisheries and Aquatic Resources declared an “all-out war” against dynamite fishing and other illegal fishing practices.
In northern Tanzania, blast fishing, which is illegal, has resurfaced in recent years as a key danger to its coral reefs. This has occurred even though major institutions like local communities and the district government have been put in place for enhanced fisheries management. The damage of blast fishing in the area has contributed to unstable coral reefs, discouragement of tourism investors, and a threat to the habitat of coelacanths in the region. Other impacts of blast fishing in the area include reports that citizens have died or lost limbs due to the blasting. The northern part of the country has many beautiful beaches and uninhabited islands. However, many investors feel and tourists are discouraged due to the fish blasting.
In Tanzania, coral reefs are essential for both ecological and socio-economic reasons. They are full of fish, lobsters, prawns, crabs, octopuses, mollusks, and sea cucumbers. In addition, coral reefs are one of the major tourist attractions in Tanzania. The coastal tourism provides a living for the people as well as foreign currency for the country. However, there has been an increase in the people living along the coast which has led to a large demand for fisheries. It has led to overexploitation and destructive fishing practices. Blast fishing has been practised in Tanzania since the 1960s. It was during the 1980s and 1990s that blast fishing was at its peak in Tanzania. For example, in Mnazi bay, Mtwara, 441 blasts were recorded in two months in 1996, and 100 blasts were witnessed through one 6 hour period in Mpovi reef.
Despite the effectiveness in killing or stunning the fish another problem with blast fishing is the inefficiency of retrieval. For every 10 that you kill only one or two will float to the surface due to damage caused to the internal air bladders of the fish. The rest will sink to the bottom. Sources : Dynamite Fishing With Jacque Coustaeu
Naval battles also tend to kill fish with the same effect of blast fishing from shells exploding in the water.
- Coral degradation through destructive fishing practices
- Blast Fishing
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