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The Online Magazine for Sustainable Seas
May, 1999 Vol. 2 No. 5

A Closer Look at Blast Fishing in the Philippines

By Rupert Sievert, CRMP






t may not be a major method of fishing like hook and line or the gill net, but explosive fishing is widespread in the Philippines. According to one estimate, about 70,000 fishers - that's 12% of the total number of capture fishers in the country - are suspected to engage in blast fishing. In every bay and in every gulf, there are always blast fishers; for every fishing ground, there is always a village known to be the residence of blast fishers; and in every village, there is always at least one tale of misfortune, of a blast fisher or another person maimed or killed because of the explosion.

The practice, of course, is illegal. Worldwide, underwater explosives find their legitimate use in the demolition of abandoned oil platforms, clearance of navigational obstruction, and conduct of military exercises. In the past, the use of explosives to collect fish specimens was even allowed. For example, in 1907-1910, the Philippine expedition of the United States Bureau of Fisheries steamer Albatross used explosives to gather reef fish samples. Two defunct fishery laws, Act No. 4003 (1932) and Presidential Decree No. 704 (1975), allowed the use of explosives for research and eradication of "whales, crocodiles, sharks or other large dangerous fishes."

But the use of explosives for fishing has never been sanctioned by law. The current applicable law, Republic Act No. 8550 (the Philippine Fisheries Code of 1998), penalizes the use of explosives with imprisonment of 5-10 years. In addition, the perpetrator forfeits his boat, equipment and catch to the government, and if the explosion injures or kills people, he can be charged with a separate criminal case. Also, the marketing of fish caught by explosives is punishable with imprisonment of 6 months to 2 years, and so is the unauthorized possession of explosives.

The law, however, has not stopped blast fishing, whether in the past, when penalty was harsher (20 years to life imprisonment) or in the present, when penalty has been made humane because of the belief that all blast fishers are poor. Enforcement has been a major issue. Only a few blast fishers have been apprehended, and fewer still have been convicted. Often, those unfortunate ones who are caught are mere followers or underlings - the "big fish" usually gets away.

Profile of the blast fisher
Contrary to widespread belief, blast fishing is not practiced exclusively by impoverished sustenance fishers. In fact, the blast fisher may be socio-economically better off than a gill net user. He may be a ring net user or purse seiner, who uses explosives to stun schools of fish attracted to floating fish aggregating devices. He is a daring individual belonging to a tightly knit group enjoying protection from apprehension and prosecution provided by some higher-status persons who are in business, politics, government and law enforcement. He is often feared in the community. He may even be considered a community leader and benefactor who allows other fishers and members of the community to gather the fish and so get a share of the catch. The whole community, in fact, may be his accomplice. They warn him about the arrival of law enforcers. They provide no information and do not cooperate in the investigation.

Explosives are powerful and dangerous tools to use under any circumstances, and blast fishers have lost limbs or even died because of defective explosives or some miscalculation. Moreover, blast fishing has other hazards. Sometimes, the blast fisher must dive great depths for his catch and thus face the risk of getting the bends, or, when using a compressor, of breathing oil-contaminated air. But, without fear of being apprehended or prosecuted, he is willing to face the risks for the promise of a big catch.

Anatomy of blast fishing
Explosives assure bigger catches because they are used only when there is a school of fish. When the blast fisher goes out to sea, he also brings along other gear like hook and line, spear guns, air compressors, poisons, fish pots and a variety of nets. It is only when he spots a school of fish or a large fish that he throws or drops the explosive in the water column. An underwater explosion makes a series of waves that spreads in the water. An initial high-intensity shock wave is generated, followed very closely by less severe pressure waves of diminishing intensity that nonetheless add to the total impact.

The initial wave is produced by the explosive substance undergoing rapid chemical decomposition, thereby violently creating sound and releasing a large volume of gas, as a gas pocket, at high pressure and temperature. Subsequent waves are created by the rapid gas expansion in the water, causing a sequence of contractions and expansions as the gas pocket rises to the surface. Meanwhile, the initial high-intensity shock wave travels outward in all directions from the point of explosion, losing its intensity with distance.

The intensity of the waves depends on the particular circumstances (depth, distance, water temperature, water layers) in which the explosion occurs, and the type and size of the explosive used. The waves traveling to the bottom may be reflected back, depending on the kind of sea floor; waves moving towards the surface either bounce back or break through the surface. Water turbulence and movement in the area also follow an explosion.

Fish with air or swim bladders - that is, most bony fishes - are the most vulnerable. The waves of the blast increase the pressure within their bladder, more so when the fish are near the water's surface. Fish without bladders (sharks and rays), shrimp, lobsters, crabs and oysters are relatively more resistant.

Fish taken by blast fishers are both pelagic and reef species, including anchovies, sardines, scads, mackerels, jacks, mullets, fusiliers, rabbitfish, surgeonfish, groupers and snappers. They show ruptured bladders and blood vessels, broken bones and mutilated bodies (especially those very near the blast).

Fish encircled by nets are also sometimes blasted before they are hauled up. The blast exerts tremendous pressure that kills, injures or stuns the fish outright, making it easier for fishers to hand-pick, scoop or spear them. Ordinarily, however, fishers are not able to collect all the fish hit by the explosion. The fish affected by the blast may be distributed over a wide area, some are carried away by currents, and others may have sunk to the bottom, too deep for diving even with the use of compressed air. Or the fishers, suddenly interrupted by the approach of law enforcers, are forced to flee. In areas outside their influence, blast fishers disappear quickly from the scene of the explosion, leaving behind a marker which will guide them later when they return to the site to gather the catch.

Within its relative effective range, the explosion upsets the established community of organisms, as well as their food webs, as the blast also strikes non-targeted, non-commercial species, juvenile fish, plankton, corals, shellfish and other invertebrates, sea mammals, turtles and birds. An explosion on or near a coral reef physically alters the reef, leveling and creating a crater, breaking the corals into rubble, reducing its relief and complexity as a habitat and lessening its aesthetic appeal. Blasted reefs support fewer fish species and lower fish biomass, thus resulting in lower fishery production. They also take a long time to recover.

A tradition of destruction
Some blast fishers refuse to believe that the cumulative effect of explosive fishing is responsible for declining fish catches. Instead, they blame the government's failure to control commercial trawlers and commercial fishing using powerful lights. In their view, blast fishing improves their chances in resource competition. They thus have no qualms about bombing coral reefs, or even artificial reefs made of tires, concrete and bamboo that are deployed by the government, non-governmental organizations and fishers associations as habitat enhancement.

Indeed, in many coastal villages, blast fishing is deeply rooted in tradition. The practice already existed before World War II, becoming extensive and rampant after the War when the ammunition, bombs and other explosives left behind in dumps and wrecks were salvaged and turned into fish bombs. Glass bottles of various sizes, weighted by sinkers made of iron or stone, served as casing. The bombs were detonated by home-made or commercial fuses.
When war ammunition was exhausted, the fishers began using miner's dynamite, and then agricultural fertilizers (ammonium nitrate, potassium nitrate and sodium nitrate) mixed with kerosene, now the most common source. Blast fishers have also learned to use battery-operated pipe bombs which explode sideways and suppress the sound of the explosion.

Every year, especially in October, the government conducts a nationwide public information campaign about the destructive effects of blast fishing. The national government has also been giving patrol boats (mostly outrigger boats with inboard motors) to the local governments who, alas, often fail to maintain them. Furthermore, the national government has trained public market inspectors and fish traders in how to detect blasted fish.

But still blast fishing continues, partly because of resource depletion and the deepening poverty in many coastal communities, but largely because law enforcement has been weak, or at best erratic. Enforcers are poorly motivated, or else are poorly equipped and ill-trained in taking evidence. Those who seriously enforce the law can be harassed or even killed. More perversely, some law enforcers are the blast fishers' protectors.

Clearly, these issues must be addressed and soon. Some say it will take at least one generation to stop a practice that is rooted in tradition. That may be so, but however long it takes, the process must begin now. We must start breaking the blast fishers' tradition of destruction, before it's too late.


Alcala, A.C. and E.D. Gomez. 1987. Dynamiting coral reefs for fish: a resource destructive fishing method, p.51-60. In B. Salvat (ed.)

Human impacts on coral reefs: facts and recommendations. Antenne Museum EPHE, French Polynesia.

Generoso, Ernesto. 1998. Is the gov't helpless vs. 70,000 blast fishers? The Freeman (October 7, 1998), p.25.

Saila, S.B., V.L. Kocic and J.W. McManus. 1993. Modelling the effects of destructive fishing practices on tropical coral reefs. Mar. Ecol. (Prog. Ser.) 94:51-60.



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