Environmental impact of fishing

The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of fishing on other elements of the environment, such as by-catch. These issues are part of marine conservation, and are addressed in fisheries science programs. There is a growing gap between the supply of fish and demand, due in part to world population growth.[1]

The journal Science published a four-year study in November 2006, which predicted that, at prevailing trends, the world would run out of wild-caught seafood in 2048. The scientists stated that the decline was a result of overfishing, pollution and other environmental factors that were reducing the population of fisheries at the same time as their ecosystems were being annihilated. Yet again the analysis has met criticism as being fundamentally flawed, and many fishery management officials, industry representatives and scientists challenge the findings, although the debate continues. Many countries, such as Tonga, the United States, Australia and Bahamas, and international management bodies have taken steps to appropriately manage marine resources.[2][3]

Reefs are also being destroyed by overfishing because of the huge nets that are dragged along the ocean floor while trawling. Many corals are being destroyed and as a consequence, the ecological niche of many species is at stake.

Effects on Marine habitat

Some fishing techniques cause habitat destruction.[4] Blast fishing and cyanide fishing, which are illegal in many places, harm surrounding habitat.[4] Blast fishing refers to the practice of using explosives to capture fish. Cyanide fishing refers to the practice of using cyanide to stun fish for collection. These two practices are commonly used for the aquarium trade and the live fish food trade.[4] These practices are destructive because they impact the habitat that the reef fish live on after the fish have been removed. Bottom trawling, the practice of pulling a fishing net along the sea bottom behind trawlers, removes around 5 to 25% of an area's seabed life on a single run.[5] Most of the impacts are due to commercial fishing practices.[6] A 2005 report of the UN Millennium Project, commissioned by UN Secretary-General Kofi Annan, recommended the elimination of bottom trawling on the high seas by 2006 to protect seamounts and other ecologically sensitive habitats. This was not done.

In mid-October 2006, United States President George W. Bush joined other world leaders calling for a moratorium on deep-sea trawling, a practice shown to often have harmful effects on sea habitat and, hence, on fish populations.[7] No further action was taken (Divek). the sea animals aquatic ecosystem may also collapse due to the destruction in the food chain.

Additionally, ghost fishing is a major threat due to capture fisheries.[8] Ghost fishing occurs when a net, such as a gill net or trawl, is lost or discarded at sea and drifts within the oceans and can still act to capture marine organisms. According to the FAO Code of Conduct for Responsible Fisheries, States should act to minimize the amount of lost and abandoned gear, and work to minimize ghost fishing.[9]


Overfishing has also been widely reported due to increases in the volume of fishing hauls to feed a quickly growing number of consumers. This has led to the breakdown of some sea ecosystems and several fishing industries whose catch has been greatly diminished.[10][11] The extinction of many species has also been reported.[12] According to a Food and Agriculture Organization estimate, over 70% of the world’s fish species are either fully exploited or depleted.[13] According to the Secretary General of the 2002 World Summit on Sustainable Development, "Overfishing cannot continue, the depletion of fisheries poses a major threat to the food supply of millions of people."[14]

The cover story of the May 15, 2003 issue of the science journal Nature – with Dr. Ransom A. Myers, an internationally prominent fisheries biologist (Dalhousie University, Halifax, Canada) as the lead author – was devoted to a summary of the scientific information. The story asserted that, as compared with 1950 levels, only a remnant (in some instances, as little as 10%) of all large ocean-fish stocks are left in the seas. These large ocean fish are the species at the top of the food chains (e.g., tuna, cod, among others). This article was subsequently criticized as being fundamentally flawed, although much debate still exists (Walters 2003; Hampton et al. 2005; Maunder et al. 2006; Polacheck 2006;Sibert et al. 2006) and the majority of fisheries scientists now consider the results irrelevant with respect to large pelagics (the open seas).[15]

The fishing down the food web is something that occurs when overfishing arises. Once all larger fish are caught, the fisherman will start to fish the smaller individuals, which would lead to more fish needing to be caught to keep up with demand.[16] This decreases fish populations, as well as genetic diversity of the species, making them more susceptible to disease, and less likely to adapt to their stressors and the environment.[17] Additionally, catching smaller fish leads to breeding of smaller offspring, which can be problematic for fish. In many species, the smaller the female, the less fecund it is, impacting the fish population.[18]

Ecological disruption

Over-fishing can result in the over-exploitation of marine ecosystem services.[19] Fishing can cause several negative physiological and psychological effects for fish populations including: increased stress levels and bodily injuries resulting from lodged fish hooks.[20] Often times, when this threshold is crossed, hysteresis may occur within the environment.[19] More specifically, some ecological disturbances observed within the Black Sea marine ecosystem resulted from a combination of over-fishing and various other related human activities which adversely affected the marine environment and ecosystem.[21] Ecological disruption can also occur due to the over-fishing of critical fish species such as the tilefish and grouper fish who can be referred to as ecosystem-engineers.[22]

Fishing may disrupt food webs by targeting specific, in-demand species. There might be too much fishing of prey species such as sardines and anchovies, thus reducing the food supply for the predators. Disrupting these types of wasp-waist species may have effects throughout the ecosystem.[23] It may also cause the increase of prey species when the target fishes are predator species, such as salmon and tuna.


Bycatch is the portion of the catch that is not the target species. These are either kept to be sold or discarded. In some instances the discarded portion is known as discards. Even sports fisherman discard a lot of non-target and target fish on the bank while fishing.

Marine debris

Recent research has shown that fishing debris such as nets, buoys, and lines, accounts for a majority of plastic debris found in the oceans,[24] such as in the Great Pacific garbage patch. Similarly, fishing debris has been shown to be a major source of plastic debris found on the shores of Korea.[25] Marine life interacts with debris in two ways; either through entanglement (where debris entangles or entraps animals), or ingestion of the debris (either intentionally or accidentally). Both are harmful to the animal.[26] Tracking garbage and monitoring the logistics of human waste disposal, especially waste materials primarily associated with fishing, is one method to reduce marine debris.[27][28] Using technological or mechanical innovations such as marine debris-clearing drones can further serve to reduce the amount of debris within oceans.[27][28] Marine debris consisting of old fishing nets or trawls can often be linked to phenomena such as ghost fishing; wherein the netting debris continues to entangle and capture fish and is referred to as ghost nets.[28] A study performed in southern Japan on octopus noted that there was an estimated mortality rate of 212,000 - 505,000 octopus killed per year within the area's fishing grounds.[29]

Importance of Recreational Fishing Impacts

Recreational fishing is fishing done for sport or competition, whereas commercial fishing is catching seafood, often in mass quantities, for profit. Both can have different environmental impacts when it comes to fishing.

Though many assume recreational fishing does not have a large impact on fish, it actually accounts for almost a quarter of the fish caught in the United States, many of those being commercially valuable fish.[30] Since recreational fishing is not nearly as regulated or monitored as commercial fishing, this is large section of environmental impact that needs to be taken into account.

Recreational fishing has its biggest impact on marine debris, overfishing, and fish mortality. Release mortality in recreational fisheries is the same as the impacts of bycatch in commercial fisheries.[31]


Fisheries management and fish farming

One method to increase fish population numbers and reduce the severity of adverse environmental impacts and ecological disturbances is the utilization of traditional fisheries management systems within fisheries.[32] Essentially, traditional fisheries management incorporates the aspects of fisheries management; however, the conservation efforts take into account concepts that place restrictions on the type of gear used and the allotment of permitted angling.[32] Traditional fisheries management also incorporates communities within its conservation efforts which often result in management scenarios where there is co-management conservation efforts led by communities.[32]

Ecosystem-based management of fisheries is another method used for fish conservation and impact remediation.[32][33] Instead of solely focusing conservation efforts on a single species of marine life, ecosystem-based management is used across various species of fish within an environment.[32][33] To improve the adoption of these types of fisheries management, it is important to reduce barriers to entry for management scenarios in order to make these methods more accessible to fisheries globally.[32]

Many governments and intergovernmental bodies have implemented fisheries management policies designed to curb the environmental impact of fishing. Fishing conservation aims to control the human activities that may completely decrease a fish stock or washout an entire aquatic environment. These laws include the quotas on the total catch of particular species in a fishery, effort quotas (e.g., number of days at sea), the limits on the number of vessels allowed in specific areas, and the imposition of seasonal restrictions on fishing.

In 2008 a large scale study of fisheries that used individual transferable quotas and ones that didn't provided strong evidence that individual transferable quotas can help to prevent collapses and restore fisheries that appear to be in decline.[34][35][36][37]

Fish farming has been proposed as a more sustainable alternative to traditional capture of wild fish. However, fish farming has been found to have negative impacts on nearby wild fish[38] and farming of predatory fish like salmon can rely on fish feed that is based on fish meal and oil from wild fish.[39]

Marine reserves

Marine reserves serve to foster both environmental protection and marine wildlife safety.[40] The reserves themselves are established via environmental protection plans or policies which designate a specific marine environment as protected.[40] Coral reefs are one of the many examples which involve the application of marine reserves in establishing marine protected areas.[40] There have also been marine reserve initiatives located in the United States, Caribbean, Philippines, and Egypt.[40] To mitigate the negative environmental impacts of fishing within marine environments, marine reserves are intended to create, enhance, and re-introduce biodiversity within the area.[40][41] As a result, the primary benefits arising from the implementation of this type of management effort include positive impacts towards habitat protection and species conservation.[40]


Based upon catch-and-release research, this method of mitigation involves several practices to reduce the negative environmental impacts of fishing that include: the duration, timing, and type of hook used during angling.[20] To increase the effectiveness of catch and release fishing and mitigate its negative impacts, species-specific guidelines are required.[20] These guidelines help tailor specific rules and regulations to specific species of fish in relation to their locations and mating and migration cycles.[20] While catch-and-release fishing has been wildly used in recreational fishing, it is also beneficial for maintaining fish populations at a stable level for commercial fisheries to receive social and economic benefits.[42] Combining catch-and-release fishing with biotelementry data collection methods allows for researchers to study the biological effects of catch-and-release fishing on fish in order to better suit future conservation efforts and remedies.[42] The environmental impact of recreational fishing may be alleviated to some extent by catch and release fishing.

See also




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  3. Juliet Eilperin (2 November 2006). "Seafood Population Depleted by 2048, Study Finds". The Washington Post.
  4. 1 2 3 Erdmann, Pet-Soede, Cabanban (2000). "Destructive Fishing Practices" (PDF). 9th International Coral Reef Symposium.
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  10. Overfishing | Greenpeace International
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  12. https://www.un.org/events/tenstories/story.asp?storyID=800
  13. http://www.johannesburgsummit.org/html/whats_new/otherstories_fishing_2808.htm
  14. Changes in the Biomass of Large Pelagic Predators – Pelagic Fisheries Research Program
  15. "Fishing Down through the Food Web". American Fisheries Society. 2015-07-18. Retrieved 2018-04-02.
  16. Sonsthagen, Sarah A.; Wilson, Robert E.; Underwood, Jared G. (2017-12-01). "Genetic implications of bottleneck effects of differing severities on genetic diversity in naturally recovering populations: An example from Hawaiian coot and Hawaiian gallinule". Ecology and Evolution. 7 (23): 9925–9934. doi:10.1002/ece3.3530. ISSN 2045-7758.
  17. Beldade, R.; Holbrook, S. J.; Schmitt, R. J.; Planes, S.; Malone, D.; Bernardi, G. (2012-06-07). "Larger female fish contribute disproportionately more to self-replenishment". Proceedings of the Royal Society B: Biological Sciences. 279 (1736): 2116–2121. doi:10.1098/rspb.2011.2433. PMC 3321707. PMID 22279163.
  18. 1 2 Daskalov, Georgi M.; Grishin, Alexander N.; Rodionov, Sergei; Mihneva, Vesselina (2007-06-19). "Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts". Proceedings of the National Academy of Sciences. 104 (25): 10518–10523. doi:10.1073/pnas.0701100104. PMC 1965545.
  19. 1 2 3 4 Cooke, Steven J.; Suski, Cory D. (2005-05-01). "Do we need species-specific guidelines for catch-and-release recreational angling to effectively conserve diverse fishery resources?". Biodiversity & Conservation. 14 (5): 1195–1209. doi:10.1007/s10531-004-7845-0. ISSN 0960-3115.
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  21. Coleman, Felicia C.; Williams, Susan L. "Overexploiting marine ecosystem engineers: potential consequences for biodiversity". Trends in Ecology & Evolution. 17 (1): 40–44. doi:10.1016/s0169-5347(01)02330-8.
  22. Cury, Bakun, Crawford, Jarre, Quinones, Shannon, Verheye (2000). "Small pelagics in upwelling systems: patterns of interaction and structural changes in wasp-waist ecosystems" (PDF). ICES Journal of Marine Science. 57: 603–618.
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  34. New Scientist: Guaranteed fish quotas halt commercial free-for-all
  35. A Rising Tide: Scientists find proof that privatising fishing stocks can avert a disaster The Economist, 18th Sept, 2008.
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Further reading

  • Castro, P. and M. Huber. (2003). Marine Biology. 4thed. Boston: McGraw Hill.
  • Hampton, J.; Sibert, J. R.; Kleiber, P.; Maunder, M. N.; Harley, S. J. (2005). "Changes in abundance of large pelagic predators in the Pacific Ocean". Nature. 434: E2–E3. 
  • Maunder, M.N.; Sibert, J.R.; Fonteneau, A.; Hampton, J.; Kleiber, P.; Harley, S. (2006). "Interpreting catch-per-unit-of-effort data to assess the status of individual stocks and communities". ICES Journal of Marine Science. 63 (8): 1373–1385. doi:10.1016/j.icesjms.2006.05.008. 
  • Myers, Ransom; Worm, Boris (2003). "Rapid worldwide depletion of predatory fish communities". Nature. 423. 
  • Polacheck, T (2006). "Tuna longline catch rates in the Indian Ocean: did industrial fishing result in a 90% rapid decline in the abundance of large predatory species?". Marine Policy. 30 (5): 470–482. doi:10.1016/j.marpol.2005.06.016. 
  • FAO Fisheries Department. (2002). The State of World Fisheries and Aquaculture. Rome: Food and Agriculture Organization of the United Nations.
  • Sibert; et al. (2006). "Biomass, Size, and Trophic Status of Top Predators in the Pacific Ocean". Science. 314 (5806): 1773–1776. doi:10.1126/science.1135347. PMID 17170304. 
  • Walters, C. J. (2003). "Folly and fantasy in the analysis of spatial catch rate data". Canadian Journal of Fisheries and Aquatic Sciences. 60 (12): 1433–1436. doi:10.1139/f03-152. 
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