{{Short description|Fishing method that paralyzes fish}} {{Use dmy dates|date=January 2022}} '''Cyanide fishing''' is a specific method of collecting live fish, mainly for use in aquariums, which involves spraying a sodium cyanide mixture into a habitat in order to incapacitate the fish there. This practice affects not only the target population, it also has negative and damaging effects on many other marine organisms, including coral and coral reefs.
==History and geography== Cyanide fishing is practiced mainly in saltwater fishing regions of Southeast Asia. Since the practice of cyanide fishing was never widely publicised or officially approved, its origins are uncertain; but it is believed to have originated in the 1950s in the Philippines.<ref name=crc>{{Cite book|last1=Dzombak|first1=David A.|last2=Ghosh|first2=Rajat S.|last3=Wong-Chong|first3=George M.|date=2006|title=Cyanide in Water and Soil|publisher=CRC Press|chapter=11.2: Use of Cyanide for Capturing Live Reef Fish}}</ref> Later in the twentieth century, the practice was adopted by some fishing operators in Indonesia, Thailand, the Maldives, and Taiwan, among others.<ref name=crc/> Cyanide fishing was initially developed to stun and capture fish for aquariums and collectors, but it was soon also used for catching fish for human consumption. It is illegal in many of the countries in which it is practiced, although these laws are often minimally enforced.<ref name=crc/> Grouper, wrasse, and coral trout are among the more popular species of fish captured through cyanide fishing.
The World Resources Institute (WRI) determined that approximately 20% of the live fish traded on the Philippine market in 1996 were caught using cyanide; assuming this is reflective of southeast Asian practice as a whole, environmental engineer David Dzombak estimates that {{Convert|12000|to|14000|ST|LT MT|-1|abbr=off|lk=on}} of live food fish are caught each year using this method.<ref name=crc/>
Colourful, particularly eccentric, and therefore rare coral reef fish are packed into plastic bags; up to two thirds of these fish die during transport. Estimates suggest 70% to 90% of aquarium fish exported from the Philippines are caught with cyanide.<ref name=Wabritz>{{Cite book|author1=Wabritz, C.|author2=Taylor, M.|author3=Green, E.|author4=Razak, T.|date=2003|title=From Ocean to Aquarium|url=https://Archive.org/details/fromoceantoaquar03wabn|series=UNEP-WCMC Biodiversity Series|volume=17|publisher=World Conservation Monitoring Centre (WCMC)|isbn=92-807-2363-4}}</ref><ref name=Barber>{{Cite journal|author1=Barber, C.V.|author2=Pratt, R.V.|year=1998|title=Poison and profits: cyanide fishing in the Indo-Pacific|journal=Environment: Science and Policy for Sustainable Development|volume=40|issue=8|pages=5–34|doi=10.1080/00139159809604600|bibcode=1998ESPSD..40h...4B |url=http://www.spc.int/DigitalLibrary/Doc/FAME/Meetings/HOF/1/IP18.pdf}}</ref><ref name=McManus>{{Cite journal|author1=McManus, J. W.|author2=Reyes, R.B.|author3=Nanola, C.L.|year=1997|s2cid=22590485|name-list-style=amp|title=Effects of some destructive fishing practices on coral cover and potential rates of recovery|journal=Environmental Management|volume=21|issue=1|pages=69–78|doi=10.1007/s002679900006|pmid=8939786}}</ref> Due to the post-capture handling stress and the effects of the cyanide, fish are bound to have a shorter life-span than usual in aquariums. According to an interview with experienced aquarium owners, they were willing to pay more for net-caught fish, because of the higher survival rate.<ref name=Tsang>{{Cite web|last=Tsang|first=Anita C.W.|date=December 2001|title=A glance at the marine aquarium fish trade in Hong Kong|url=http://www.HKU.hk/ecology/porcupine/por24/24-vert-fish.htm|website=www.HKU.hk|publisher=Porcupine!|issue=24|pages=9–12|access-date=27 May 2005}}</ref> They also said they would not trust an ecolabelling system, which can be misleading.{{Citation needed|date=March 2016}}
The basis for this illegal fishing method is, among others, the rising demand for live fish in the higher-class restaurants of the big cities, particularly in rich, nearby countries, which pay increasingly high prices. The extremely low wages of the fishermen in remote, underdeveloped areas, where there are no alternative sources of income, drive them to endure the health risks and possible prosecution.{{Citation needed|date=January 2022}}
The practice has led to conflict between Chinese fishermen and the Taiwanese coast guard.<ref>{{cite web |title=Minister slams Chinese cyanide fishers |url=https://www.taipeitimes.com/News/front/archives/2025/09/16/2003843861 |website=taipeitimes.com |date=16 September 2025 |publisher=Taipei Times |access-date=4 October 2025}}</ref>
==Method== {{More citations needed section|date=January 2022}} The fishermen dive into the sea, usually without artificial breathing aids, although some use a highly dangerous apparatus (commonly garden hose surface-fed from the type of air compressor commonly used to power jackhammers). When they reach the coral reefs, they spray the poison between the individual layers, after which the yield is collected. Edible fish, of which a number are sold for general consumption, are first placed for ten to fourteen days in clean water for 'rinsing'. Recent studies have shown that the combination of cyanide use and stress of post capture handling results in mortality of up to 75% of the organisms within less than 48 hours of capture. With such high mortality numbers, a greater number of fish must be caught in order to supplement post-catch death.
Cases have been reported of fishermen dumping drums of concentrated cyanide in places where fishing is difficult or economic times are hard.<ref name=crc/> Such high concentrations normally kill most of the haul, but in these cases, the objective is no longer to catch live fish, but to catch the largest amount possible.{{Citation needed|date=January 2022}}
==Mechanism== In seawater, sodium cyanide breaks down into sodium and cyanide ions. Cyanide inhibits cellular respiration, leading to death.<ref>{{cite journal|title=Cyanide and Cyanogenic Compounds—Toxicity, Molecular Targets, and Therapeutic Agents|doi=10.3390/biom14111420|date=2024-11-07|last1=Lachowicz|first1=Joanna|last2=Alexander|first2=Jan|journal=Biomolecules|last3=Aaseth|first3=Jan|volume=14|issue=11 |page=1420 |doi-access=free |pmid=39595596 |pmc=11591714 }}</ref> Coral polyps, young fish, and spawn are most vulnerable; adult fish can take somewhat higher doses. The use of cyanide is known to cause mortality on laboratory corals in measured doses, however these data are very difficult to quantify in regard to wild populations.<ref name=Jones>{{Cite journal|author=Jones, R.J.|date=1997|title=Zooxanthellae loss as a bioassay for assessing stress in corals|journal=Marine Ecology Progress Series|volume=149|pages=163–171|doi=10.3354/meps149163|title-link=bioassay|bibcode=1997MEPS..149..163J|doi-access=free}}</ref>
==Habitat destruction== {{See also|Habitat destruction}} Many fishing and diving areas across the whole of South East Asia, already severely damaged from the impact of dynamite fishing, have been ruined or totally lost through cyanide fishing. Cyanide concentration slows photosynthesis in zooxanthellae, which results in coral reefs losing colour; it also eliminates one of their major food sources.<ref name=crc/> Even at very low doses, cyanide results in higher mortality levels among corals.
==References== {{Reflist}}
==External links== *{{in lang|de}} [https://web.archive.org/web/20060414065525/http://nikswieweg.colibri-reisen.de/reisen/philipp/palawan2b.htm#Dynamit%20&%20Cyanid nikswieweg.colibri-reisen.de]: detailed article on illegal fishing methods in Palawan, Philippines *[https://web.Archive.org/web/20070529170837/http://www.PetStoreAbuse.com/cyanide.html A Poisonous Business] - information on cyanide fishing that supplies the pet trade
{{Fishing tackle|expanded=techniques}} {{Fisheries and fishing}} {{Authority control}}
Category:Fishing techniques and methods Category:Environmental impact of fishing Category:Water pollution