Blast Fishing and Coral Reef Damage

Coral reefs are one of the Earth’s most vital ecosystems. Home to thousands of highly specialized species, coral reefs are considered by scientists to be the most diverse marine ecosystem.

Using the sun's energy and minerals from seawater, corals secrete limestone skeletons which provide habitat and shelter for fish and other reef animals. The accumulation of coral sediments over thousands of years creates tall oceanic islands and extensive barrier reefs able to withstand the most powerful storms.

Coral reefs are also highly productive, and are a critically important fishery for many tropical nations. In areas where dive tourism has been developed, coral reefs earn millions of dollars annually for local economies.

Of course all these benefits depend on the presence of living coral cover. Tragically, coral reefs are seriously threatened by human activities in many areas of the tropics. In some countries, it is estimated that more than 50% of the coral cover has been destroyed.

Large blasted areas are slow to recover because corals have difficulty establishing on loose or sandy substrate.

Lacking suitable habitat, reef fish quickly abandon a demolished reef and local fisheries collapse.

Rates of erosion increase because reef sediments are no longer replenished by living coral.

Young corals have little opportunity to establish on the shifting rubble and quickly become smothered by sand or algae.

Recent studies indicate that it can take more than a century for a reef to recover by natural means once the live coral cover has been destroyed.

Unexploded bomb, Phillipines. Lack of enforcement and the ready availability of explosives contributes to the pervasiveness of blast fishing. © 2001 Jeffery N. Jeffords.

Reef fish killed by a blast (Moorish idol, bannerfish, soldierfish, basslet). Blast fishing kills reef fish indiscriminantly, including many small fish that have little or no food value.
© 2001 Mark V. Erdmann.

Closeup of a branching coral thicket destroyed by a blast (and a dead bigeye). Blast fishing obliterates the fish habitat provided by corals.
© 2001 Mark V. Erdmann.

Close up of a table coral shattered by a blast. Powerful underwater explosions wreck even well-established coral colonies that survived many strong storms in the past.
© 2001 Mark V. Erdmann.

Blast crater in a branching coral thicket. Blast craters have a distinctive circular shape. This blast has flattened well-developed reef framework that was about a meter deep.
© 2001 Michael D. Moore.

Loose coral rubble produced by extensive blast fishing. Young corals that settle on this type of substrate are easily killed by algae or sand scour, slowing reef recovery processes.
© 2001 Mark V. Erdmann.

Coral rubble overgrown by algae. Small herbivorous fish are important because they crop fast growing algae that can kill corals. Lacking shelter, fish abandon the reef and algae soon dominates. © 2001 Helen E. Fox.

Repeated heavy blasting creates vast deserts of coral rubble, resulting in total collapse of the local ecosystem. Recovery timescales for reefs this severely damaged exceed a century. © 2001 Mark V. Erdmann.

As reef fish stocks decline, pressure from blast fishing appears to be increasing. This dive site in Indonesia (previously in excellent condition) was destroyed by blast fishing in the mid 90's. © 2001 Michael D. Moore.

Diver inspecting a blast crater near a resort area in Indonesia. Community-based management can resolve conflicts between subsistence fishers and dive operators over how reefs are used. © 2001 Michael D. Moore.

Findings from recent ecological experiments show that fish and coral will repopulate even severely degraded coral reefs if certain basic requirements are met. These include good water quality, a stable structure that is raised off of the bottom, non-toxic shaded surfaces for coral settlement, and abundant living space for small fish (Fox, H., Pet, J., Dahuri, R., Caldwell, R. [in review] "Coral restoration after blast fishing in Indonesia" Proceedings, 9th International Coral Reef Symposium).

EcoReefs ceramic artificial reefs expand on these ecological principles by combining in the module design a stable 2:1 aspect ratio, non-toxic materials, raised and shaded surfaces for coral recruits, and branches to create spatial complexity for fish. EcoReefs installations make attractive dive sites and can be deployed over large blasted areas.