Blast fishing
Encyclopedia
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
, as the explosion often destroys the underlying habitat (such as coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
s) 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
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, as well as in the Aegean Sea
Aegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...
, and coastal Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. In the Philippines, where the practice has been well-documented, blast fishing was known prior to World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, as this activity is mentioned by Ernst Jünger
Ernst Jünger
Ernst Jünger was a German writer. In addition to his novels and diaries, he is well known for Storm of Steel, an account of his experience during World War I. Some say he was one of Germany's greatest modern writers and a hero of the conservative revolutionary movement following World War I...
in his book Storm of Steel
Storm of Steel
Storm of Steel is the memoir of German officer Ernst Jünger's experiences on the Western Front during the First World War. It was originally printed privately in 1920, making it one of the first personal accounts to be published. The book is a graphic account of trench warfare...
. 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
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
or, more commonly, homemade bombs
Improvised explosive device
An improvised explosive device , also known as a roadside bomb, is a homemade bomb constructed and deployed in ways other than in conventional military action...
constructed using a glass bottle with layers of powdered potassium nitrate and pebbles or an ammonium nitrate and kerosene
ANFO
ANFO is a widely used bulk industrial explosive mixture. It consists of 94 percent porous prilled ammonium nitrate , that acts as the oxidizing agent and absorbent for the fuel — six percent Number 2 Fuel Oil...
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
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
; 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 to be the biggest threat 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.
Community-based Enforcement
In TanzaniaTanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
, 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
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
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 Area
Marine Protected Area
Marine Protected Areas, like any protected area, are regions in which human activity has been placed under some restrictions in the interest of conserving the natural environment, it's surrounding waters and the occupant ecosystems, and any cultural or historical resources that may require...
s (MPAs) is key in the patrolling of illegal fishing areas.
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 hydrophone
Hydrophone
A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change...
s 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
Patrol boat
A patrol boat is a relatively small naval vessel generally designed for coastal defense duties.There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or police force, and may be intended for marine and/or estuarine or river environments...
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.
Tanzania
In northern Tanzania, blast fishing, which is illegal, has re-emerged 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 coelacanthCoelacanth
Coelacanths are members of an order of fish that includes the oldest living lineage of Sarcopterygii known to date....
s 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
Overexploitation
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Sustained overexploitation can lead to the destruction of the resource...
and destructive fishing practices
Destructive fishing practices
The phrase destructive fishing practices has been featured in international fisheries literature for around three decades. No widely accepted definition of the phrase exists, and this will almost certainly remain the situation, given very different national and industry perspectives...
. 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.
Indonesia
Blast fishing in IndonesiaIndonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
has been around for over 50 years. The use of bombs made with kerosene and fertilizer
ANFO
ANFO is a widely used bulk industrial explosive mixture. It consists of 94 percent porous prilled ammonium nitrate , that acts as the oxidizing agent and absorbent for the fuel — six percent Number 2 Fuel Oil...
is very popular in the region. In the market in the city of Makassar
Makassar
Makassar, is the provincial capital of South Sulawesi, Indonesia, and the largest city on Sulawesi Island. From 1971 to 1999, the city was named Ujung Pandang, after a precolonial fort in the city, and the two names are often used interchangeably...
, 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
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
which was in plentiful supply after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. 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
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
from the explosion are collected.
Further reading
- Verheij E., Makoloweka S., Kalombo H. Collaborative coastal management improves coral reefs and fisheries in Tanga, Tanzania (2004) Ocean and Coastal Management, 47 (7-8 SPEC. ISS.), pp. 309-320.
- Martin, G. (2002, May 30). The depths of destruction Dynamite fishing ravages Philippines' precious coral reefs. Retrieved October 25, 2009, from http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/05/30/MN232485.DTL
- Bell J.D., Ratner B.D., Stobutzki I., Oliver J.Addressing the coral reef crisis in developing countries (2006) Ocean and Coastal Management, 49 (12), pp. 976-985.