Blast fishing
Blast fishing, fish bombing, dynamite fishing or grenade fishing is a destructive fishing practice using explosives to stun or kill schools of fish for easy collection. This often illegal practice is extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat that supports the fish. The frequently improvised nature of the explosives used, and undetonated charges, means danger for fishermen and divers as well, with accidents and injuries.
Description
Although outlawed in some parts of the world, 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 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, ironically termed expanding bait, 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 amount of fish float to the surface, but most sink to the seafloor. 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.
Inefficiency
Blast fishing is inherently inefficient in retrieving killed and stunned fish. For every ten fish killed, only one or two float to the surface, due to damage caused to their otherwise buoyant internal air bladders. The rest sink to the bottom.File:The Royal Navy on the Home Front, 1914-1918 Q18845.jpg|thumb|Royal Navy sailor with a fish stunned by a depth charge's explosion off Harwich, 15 April 1918
Shells exploding in the water during naval battles also tend to kill fish with the same effect of blast fishing, only without any systematic attempt to collect the harvest.
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 tanks 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 the 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.
Control
Community-based enforcement
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 the Philippines have reduced the amount of blast fishing occurrences there. Based on dialogue with stakeholder groups in Southeast Asia and people of Tanzania and the 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 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.
Centrally governed enforcement of blast fishing sometimes has limited success, due to resistance of local populations and mistrust of central governments. Bottom up systems based around clearly defined public benefits and education are more beneficial. Effective MPAs have the backing of local leadership and populations due to clearly defined benefits of conservation/ecosystem services. It has also been shown that effective MPAs have local stakeholders that have accurate perceptions of the environmental health of the region. When coastal residents believe that the ecosystem is healthier than indicators such as species diversity, population, and habitat distribution, they may be less likely to support the MPA. Due to this, effective blast fishing community control relies on education campaigns that bring awareness to the relationship between fish stock and fishing rates.
Blast monitoring programs and eradication methods
This method involves seismic technology developed by the US Government for detecting underwater explosions. Re-adapted for use as background blast monitoring equipment Hong Kong in 1995, first installed in the northeastern waters. Fixed monitoring locations were established in 2006, notably one near to the Jockey Club HSBC WWF Hong Kong Hoi Ha Marine Life Centre. Data from these units were used for discussions with the Marine Police and the Agriculture, Fisheries and Conservation Department. The emphasis for these discussions was placed on protection of the Marine Parks, the last Marine Park bombing occurred in Hoi Ha Wan Marine Park in October 1999. With the assistance of community programs from NGO's, education awareness from the AFCD and diligent patrols by the Marine Police Blast fishing was completely eradicated from Hong Kong waters in 2011.In 2006 background blast monitoring with this same equipment was installed at Mabul Island in Sabah, Malaysia. In 2014 the Reef Defenders began an aggressive program to create a network of blast monitoring systems throughout South-East Asia. BBM is important to guide community-based eradication programs, data collected shows that with the use of community-based programs in tandem with BBM, the levels of blast fishing can be reduced by up to 90%. This has already been observed in multiple areas, more importantly, there is a significant reduction in other destructive fishing methods, shown by recovery in fish stocks.
In 2015 and 2017, conducted proof of concept demonstrations that ShotSpotter urban gunfire system could be adapted for underwater use in Kota Kinabalu and Semporna, Malaysian Borneo protected Marine Parks. In 2018, published research demonstrating real-time fish blast location in Sabah, Malaysia using a networked hydroacoustic array based on the ShotSpotter gunshot location system. In 2020, Stop Fish Bombing's Malaysia team met with Sabah Parks officials to explain the project approach and provide the ShotSpotter Respond App leading to the first apprehension of Fish Bombers by Marine Police in response to Stop Fish Bombing alert.