Course:CONS200/2023/An Overview of Bottom Trawling Policies in Europe

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Bottom trawling is a common form of fishing that is practiced all over the world. Bottom trawling consists of large fishing vessels dragging nets across the seafloor in order to capture their target species. This method of fishing may be effective but it is very harmful to the oceanic ecosystem as it destroys the natural form of the seabed. When the net is drug along the floor of the ocean it often pulls out coral reefs, aquatic plants, and other structural features that many species rely on[1]. As bottom trawling may help with providing natural resources it ultimately plays a factor in habitat degradation. Since a large amount of biodiversity is found at the bottom of the ocean, trawling poses a large threat to the oceanic biodiversity of Europe[2]. Europe is home to many diverse ecosystems including the Arctic and Atlantic Ocean as well as the Mediterranean Sea. After the negative impacts of bottom trawling were discovered the European Union (EU) and European Commission (EC) acted quickly to form policies in order to preserve the oceanic environment[3]. With heavier regulations in place to protect the biodiversity of European fisheries, a decrease in the amount of destruction done by bottom trawling is expected[3]. If solutions to bottom trawling are not practiced and refused by the public, the possibility of native species in Europe going extinct are higher as well as the inability to provide certain types of seafood throughout Europe.

(Basic bottom trawling setup)

Policy History

Common Fisheries Policy

The EU is made up of multiple countries making it difficult to create a comprehensive management plan that identifies and incorporates the needs and perspectives of each country. In order to solve this issue and govern all fisheries in the EU the Common Fisheries Policy (CFP) was created in 1983[4]. With the creation of the CFP the conservation and fisheries interests of all countries in the EU can be taken into account allowing for equal management[4]. The CFP also allows for the sustainable exploitation of fish stocks in EU waters all while safeguarding the variety of marine ecosystems which are vital to the health and productivity of the fishery[4].

Deep Sea Access Regulation

The Deep-Sea Access Regulations in the EU were created to further protect vulnerable marine ecosystems (VMEs)[3]. The Deep-Sea Access Regulations are designed to prevent bottom trawling within a certain part of the water column[3]. The area that is most heavily impacted by bottom trawling is anything below 800m deep which is why the act prohibits bottom trawling below 800 m, protecting the VMEs below[3]. This act does not eliminate the use of bottom trawling as EU vessels are still able to conduct bottom contact fishing in waters where the depth is between 400 and 800 and within the already established bottom-fishing footprint as per the EU regulations of 2016[3]. Other regulations governing bottom trawling may apply in certain zones of EU waters[5].

Habitat Directive

The preservation of biodiversity in the European Union relies heavily on the Habitat Directive. The Habitat Directive outlines the goals related to the conservation of species and their natural habitats within the EU[6]. The focus of the directive is the conservation of migratory species[6]. Since the EU encompasses such a large area, there are a variety of migratory species that move throughout the EU with varying importance to each country[6]. The Habitat Directive also focuses on the conservation of wild species that are of community interest or have a favorable conservation status[6]. The Habitat directive uses habitat protection and restoration efforts in order to conserve species of interest[6]. These objectives aim to promote regional biodiversity as well as the conservation of migratory species and their habitats all while considering the economic, social, and cultural factors associated with conservation[6].

European Union Biodiversity Strategy for 2030

The European Union has created a very progressive conservation strategy with the introduction of the Biodiversity Strategy for 2030[7]. The Biodiversity Strategy aims to put an end to biodiversity loss, improve restoration efforts in degraded areas, expand the use of protected areas, and improve governance throughout the EU[7]. Since bottom trawling can be a cause of habitat degradation and biodiversity loss the EU will likely impose greater restrictions of bottom trawling to meet the goals of the Biodiversity Strategy for 2030[7]. The increase in protected areas will further limit the waters in which bottom trawling can take place[7].

Monitoring & Enforcement

(Vessel Monitoring System: Ship Tracking with a Difference)

Governments and corporations such as the EU monitor bottom trawling through a number of different metrics[8]. Some of these metrics include, species richness, and abundance, biomass and many more[8]. In previous years there continued to be a massive issue regarding monitoring coastal vessels, and recording their data such as impact assessments and number of vessels[8]. Through systems such as the Vessel Monitoring System (VMS) improvements have been made. With the ability to track vessels' position, speed and logging this information into a database, the Vessel Monitoring System has proven to be effective. Monitoring vessels policies can be improved to regulate marine species abundance[8]. The Vessel Monitoring System not only monitors vessels but acts as a tool for enforcement purposes[9]. Patterns and movements of ships are easily tracked and used for further control and enforcement[9].

Scale of the Problem (Ecological Impact)

Fishing is one of the main methods of depleting the ocean of its resources and "affecting marine ecosystems"[10]. Bottom trawling in Europe has been going on for centuries with particular species targeted[10].

Biomass Decreasing
(Broken coral via bottom trawling)

When exploring the negative impacts of bottom trawling a decrease in marine biomass is at the forefront[11]. Biomass can be thought of as the net weight of a catch regardless of species. Since bottom trawling does not allow fishermen to target specific species, a large portion of the total catch is bycatch (non-target species)[11]. There have been multiple studies that show the correlation between bottom trawling and a decrease in marine biomass[11]. An increase in the frequency and scale of trawling has been linked with a mean decrease in biomass resulting in depletion of oceanic resources[11].

(Species threatened by bottom trawling)
Biodiversity Decreasing

Bottom trawling has been known to have a negative impact on the biodiversity of the world's oceans[12]. The effect on larger target species has been studied and managed properly but non-target aquatic organisms are often the ones who suffer the brunt of the negative effects[12]. Since bottom trawling involves dragging gear close or on the ocean floor, many organisms in the benthic community are negatively impacted by bottom trawling[12]. Organisms like bivalves, small crustaceans, and echinoderms are removed, damaged, or killed during the process of bottom trawling[12]. There has been a great decline in the biodiversity of shellfish in areas where bottom trawling is a prominent method of fishing [13]. Without improved management techniques, bottom trawling will continue to contribute to the loss of biodiversity in the world's oceans[13].

Sediment Modification

Given the process of bottom trawling, the morphology of the ocean floor is altered with each pass of a trawling vessel[14]. Grounds that have been trawled for decades have shown heavy modification due to the weight of trawling equipment passing over[14]. The alteration of sediment regimes disrupts the ecology of the benthic community as many species rely on the soft sediment for habitat, cover from predators, and hunting grounds[14]. After the sediment is disrupted, it can be carried great distances by ocean currents modifying not only the area trawling takes place but also surrounding areas outside the fishing grounds[14]. A continuation of sediment modification will lead to increased disruption of the benthic community and an overall loss in biodiversity and biomass[14].

Ocean Acidification

Trawling produces 6 to 15 million tons of carbon dioxide annually around the world[15]. That is equivalent to the 900 million tons of carbon dioxide that aircraft emits annually[15]. As it drags along the bottom, it obliterates marine ecosystems and emits massive amounts of carbon. Bottom trawling causes the seas to become more acidic and adds to global warming as a result[15].

Bycatch and Discards

Bottom trawling, like other methods of trawling, has the potential to result in bycatch, which is the unintentional capture of species that are not intended targets[16]. Ecological disruptions and conservation issues can emerge from bycatch in bottom trawling, which might involve immature or noncommercial fish, endangered or protected species, and other untargeted marine animals[16]. These phenomenon's damage the biodiversity of marine species seriously and these losses are totally unnecessary.

Possible Solutions/Alternatives

As bottom trawling can be argued to be efficient in the process of obtaining natural resources, however it is clear it produces more harm than good. It is important to find sustainable solutions or alternatives in order to continue to obtain seafood food from the sea floor without depleting and destroying resources. A main alternative that has been used and studied is the use of baited creels[17]. Creels are essentially traps baited for a specific type of species[17]. This is not only an alternative method to bottom trawling but a solution as it has been proven to have a low impact. As bottom trawling often results in the harvest of unwanted species, baited creels are effective as they reduce the amount of bycatch[17].

(Creels in Loch Gairloch)

Implementing and enforcing marine protected areas (MPAs) is another possible solution and alternative to bottom trawling [18]. Species and habitats can be maintained, protected and restored through active management of MPAs, thereby helping to reduce the decline in biodiversity and productivity[19]. MPA's can also be adapted depending on the health of the resource to impose stricter or more lenient regulations[18].

To mitigate the harmful effects of bottom trawling more sustainable fishing methods can be used[20]. These methods include utilizing selective gear and decreasing fishing in less biodiverse areas. Fishing gear can be modified by utilizing bigger mesh sizes to let smaller, non-target species escape and by employing escape panels or grids to minimize the bycatch of vulnerable species[21]. In addition, investing in alternative fishing methods would be beneficial as well[22]. These methods include trap fishing or pot fishing, which cause less environmental damage compared to bottom trawling[22].

Lastly, the use of electronic monitoring systems (EM) can be a useful solution. It often incorporates onboard cameras, global positioning systems, sensors, and data recorders to better manage and control fishing vessels.[23]. Governments can use EM systems and satellite-based VMS to monitor fishing activities and make sure regulations are being followed[24] . The EM systems can also be used to help inform management decisions based on fishing pressure in the area[24].


The ocean provides a vast amount of resources for humans and aquatic organisms alike. Unfortunately, through unsustainable practices such as overfishing via bottom trawling the oceans resources are being depleted. Bottom trawling is a very popular method of fishing across Europe but it has been banned by many countries after seeing its negative effects. Commercial fishing firms like this technique because it is effective and affordable at catching big numbers of fish simultaneously[25]. Even though bottom trawling is an effective method of fishing, there continues to be an increase in negative impacts. These impacts include decreases in marine biomass, risks to oceanic biodiversity, ocean acidification, sediment modification, and ultimately climate change.

Bottom trawling issues may be resolved by taking steps such as creating marine protected areas, promoting sustainable fishing techniques (baited creels), putting ecosystem-based fisheries management into place, improving and monitoring systems and increasing the public's knowledge[26]. The implementation of these possible alternatives can allow the next generation to have more marine biodiversity and allow the oceans to continue to provide resources without getting to the point of depletion.


  1. A. F., Johnson (2015). "Effects of bottom trawling on fish foraging and feeding". Retrieved Jan 18, 2023.
  2. O. R., Eigaard (2017). "The footprint of bottom trawling in European waters: distribution, intensity, and seabed integrity". ICES Journal of Marine Science. Retrieved Jan 18, 2023. line feed character in |title= at position 53 (help)
  3. 3.0 3.1 3.2 3.3 3.4 3.5 E., Alberts (2022). "Europe moves to protect deep-sea sites in Atlantic from bottom fishing. Newstex". Retrieved Jan 18, 2018. line feed character in |title= at position 72 (help)
  4. 4.0 4.1 4.2 Peñas Lado, Ernesto (2016). The Common Fisheries Policy. John Wiley & Sons, Ltd. p. 18. ISBN 9781119085676.
  5. "Regulation (EU) 2016/2336 of the European parliament and of the council". Official Journal of the European Union: 1–19. 2016.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 Mehtälä*, Johanna; Vuorisalo, Timo (2007). "Conservation Policy and the EU Habitats Directive: Favourable Conservation Status as a Measure of Conservation Success". Wiley InterScience. 17: 363–375.
  7. 7.0 7.1 7.2 7.3 Hermoso, V., Carvalho, S. B., Giakoumi, S., Goldsborough, D., Katsanevakis, S., Leontiou, S., Markantonatou, V., Rumes, B., Vogiatzakis, I. N., & Yates, K. L. (2022). The EU biodiversity strategy for 2030: Opportunities and challenges on the path towards biodiversity recovery. Environmental Science & Policy, 127, 263-271.
  8. 8.0 8.1 8.2 8.3 McLaverty, C., Eigaard, O. R., Olsen, J., Brooks, M. E., Petersen, J. K., Erichsen, A. C., van der Reijden, K., & Dinesen, G. E. (2023). European coastal monitoring programmes may fail to identify impacts on benthic macrofauna caused by bottom trawling. Journal of Environmental Management, 334, 117510-117510.
  9. 9.0 9.1 Hintzen, N. T., Piet, G. J., & Brunel, T. (2010). Improved estimation of trawling tracks using cubic hermite spline interpolation of position registration data. Fisheries Research, 101(1), 108-115.
  10. 10.0 10.1 Ole R., Eigaard (2017). "The footprint of bottom trawling in European waters: distribution, intensity, and seabed integrity" (PDF). ICES Journal of Marine Science: 19.
  11. 11.0 11.1 11.2 11.3 Hiddink, J. G.; Jennings, S.; Sciberras, M.; et, al. (2017). "Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance". Proceedings of the National Academy of Sciences. 114: 8301–8306.
  12. 12.0 12.1 12.2 12.3 Olsgard, F.; Schaanning, M. T.; Widdicombe, S.; Kendall, M. A.; Austen, M. C. (2008). "Effects of bottom trawling on ecosystem functioning". Journal of Experimental Marine Biology and Ecology. 366: 123–133.
  13. 13.0 13.1 Cook, R., Fariñas-Franco, J. M., Gell, F. R., Holt, R. H. F., Holt, T., Lindenbaum, C., Porter, J. S., Seed, R., Skates, L. R., Stringell, T. B., & Sanderson, W. G. (2013). The substantial first impact of bottom fishing on rare biodiversity hotspots: A dilemma for evidence-based conservation. PloS One, 8(8), e69904-e69904.
  14. 14.0 14.1 14.2 14.3 14.4 Paradis, S.; Puig, P.; Masqué, P.; et al. (2017). "Bottom-trawling along submarine canyons impacts deep sedimentary regimes" (PDF). Scientific reports. 7: 1–12. Explicit use of et al. in: |first4= (help); |first4= missing |last4= (help)
  15. 15.0 15.1 15.2 L, Jennifer. "Bottom Trawling Fishing Emits as Much Carbon Emission as Aviation". Carbon Credits. Check date values in: |archive-date= (help)
  16. 16.0 16.1 Pennino, M. Grazia (02 June 2011). "Fishery discards and bycatch: solutions for an ecosystem approach to fisheries management?". Ecosystems and Sustainability: 317–333. Check date values in: |date= (help)
  17. 17.0 17.1 17.2 Morello, E. B., Antolini, B., Gramitto, M. E., Atkinson, R. J. A., & Froglia, C. (2009). The fishery for nephrops norvegicus (linnaeus, 1758) in the central adriatic sea (italy): Preliminary observations comparing bottom trawl and baited creels. Fisheries Research, 95(2), 325-331.
  18. 18.0 18.1 The Government of Canada (2023.02.08). "Marine Protected Areas". Retrieved 2023.02.08. Check date values in: |access-date=, |date= (help)
  19. Day, John (2014). Large marine protected areas – advantages and challenges of going big. pp. 24–30.
  20. Marine Stewardship Council. "What is sustainable seafood?". Marine Stewardship Council. Retrieved 2023.04.14. Check date values in: |access-date= (help)
  21. "Relative Catch Performance of Two Gear Modifications Used to Reduce Bycatch of Undersized Fish and Shrimp in Mediterranean Bottom Trawl Fisheries". Marine and Coastal Fisheries. 2021.09.23. Check date values in: |date= (help)
  22. 22.0 22.1 Petetta, Andrea. "Pots as alternative and sustainable fishing gears in the Mediterranean Sea: an overview". Springer Link. Check date values in: |archive-date= (help)
  23. Legorburu, Gonzalo. Increasing the functionalities and accuracy of fisheries electronic monitoring systems. onlinelibrary.wiley. pp. 901–926.
  24. 24.0 24.1 Chang, S.J. "Satellite-based vessel tracking and monitoring as the long range mode of AIS". IEEE.
  25. Hooper, Ellie (2020.04.11). "What is bottom trawling and why is it bad for the environment?". Greenpeace. Check date values in: |date= (help)
  26. Jankowska, Emilia (June 2, 2022). "Climate benefits from establishing marine protected areas targeted at blue carbon solutions". Proceedings of theNational Academy of Sciences.




Seekiefer (Pinus halepensis) 9months-fromtop.jpg
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