A10. Fyke net

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1. Application and Purpose

Fyke nets have several uses, including:

  • Catch migratory fish.
  • Catch fish in marshland and lagoons where electrofishing is impossible because of inappropriate substrate, salinity or width.
  • Effective study of the direction of movement of fish between two tributaries and the main river or associated floodplains. Mainly used in marine environments, estuaries or shallow inland water.

The following applies to the methods use in rivers and estuaries to monitor fish.

2. Method summary

A fyke net is a passive fish trap made of a cylindrical netting bag. It is composed of several interconnected net cones held together by wood or metal rings. The cones funnel the fish forward but make it impossible to turn around. The last part of the cylinder, the ‘heart’, can be opened and emptied. One or two wings, made of fine mesh netting, are fastened between the lateral margin of the first hoop and the bank, in order to guide fish toward the net cylinder. Fyke nets can measure between 2 m and 7 m long and are fixed to the substrate (or slightly above) by anchors or stakes. When checking the trap, the hoop is lifted sequentially from the front, forcing fish through the funnels and into the heart. Following deployment, nets are checked daily or on every tide to check for fish (which are counted, measured and maybe tagged). Checking is also undertaken to ascertain the condition of the equipment, making sure that there are no holes, and mammals or birds caught in the netting.  

3. Advantages

  • Light equipment, relatively simple to operate and install by one or two people, even in dense aquatic vegetation or woody debris.
  • Can be installed in still or flowing water.
  • Can be baited to increase efficiency.
  • Can be used to monitor fish over a longer period than e.g. electric fishing or seine netting that only catch fish whilst the operators are actively fishing.
  • Not harmful for fish if used correctly (nets should be checked at least once per day)
  • Results in far fewer fish mortalities and injuries compared with gill nets. Most fish can be re-released.
  • Less risk to diving birds than gill nets.
  • Can be set from the shore (in shallow wadeable water) or from a boat.

4. Disadvantages

  • Difficult to set in strong currents, deep water, or steep channels.
  • Location on riverbed depends on substrate and anchor strength.
  • Fish may be eaten by other fish or crabs whilst in the trap (Portt et al. 2006).
  • Bias towards mobile cover-seeking species, benthic species and larger fish (Breen and Ruetz, 2006; Hubert and Pope, 2012).
  • Catch rates are highly variable, which means that relatively large numbers of nets are required to detect changes in relative abundance (Portt et al. 2006).
  • Can be a hazard to navigation.
  • May influence predator’s stomach content and should be considered
  • Predatory fish caught in fyke net may result in underestimation of the catch of prey species and may overestimate the contribution of these species to the diet of the predatory fish.

5. Recommendation for method application

  • Avoid fyke nets in areas with low oxygen levels, too high temperatures and shallow water (<30 cm deep).
  • Maintain consistent tidal and lunar cycle conditions (for eels).
  • Research fish behaviour and the habitat where the fyke net is to be installed.
  • Record and maintain details of net deployment including fishing effort (number & size of nets and duration), location, and ambient conditions, e.g. state of tide, freshwater flow, temperature, time of day
  • Fyke wings must be opened one at a time and fixed tightly to the bank, a tree, or something secure/stationary (such as an anchor or stake).
  • Damage caused by mammals is greatly reduced if the net opening is completely submerged as they cannot easily enter it, however, damage from certain species, e.g. otters, mink and beavers may occur
  • Otter guards are required by law to be fitted in all fyke nets deployed in English rivers
  • Consent is required from the appropriate body (Environment Agency in England) in order to use fyke nets.
  • Select and combine different fykes to target a range of species.
  • Check traps (capture and condition) everyday (preferably morning) or on every tide.
  • Process biometry quickly and release fish far from the trap.
  • Be consistent in net length, height, mesh opening size, shape, and number of hoops during the survey.
  • Rinse, clean and dry fyke net when moving sites, to prevent the spread of pathogens and invasive species.
  • Waterproof labels with researcher’s contact information are important to avoid vandalism or to be informed of problems with the net.
  • To acquire data on fish behaviour, sample effort, fishing time and the entire width covered by the equipment (wings and cylinder) should be compared with tide and environmental factors.

6. Cost

Single fyke nets are available for £100 - £200 each.

7. References

  1. Breen, M. J. and Ruetz, C. R. (2006) ‘Gear Bias in Fyke Netting: Evaluating Soak Time, Fish Density, and Predators’, North American Journal of Fisheries Management, 26(1), pp. 32–41. doi: 10.1577/m05-013.1.
  2. Environmental Protection (Water) Policy (2018) Sampling fish communities using fyke nets - Monitoring and sampling manual.
  3. Hubert, W. A. and Pope, K. L. (2012) ‘Capture Techniques Chapter 6 Passive Capture Techniques’, in Zale, A. V. , Parris, h D. L. Sutton, T. M. (ed.) Fisheries techniques, 3rd edition. 3rd edn. Bethesda, Maryland: American Fisheries Society, pp. 223–265.
  4. Lake, M. (2013) Freshwater fish: passive nets - fyke nets. Available at: http://www.doc.govt.nz/Documents/science-and-technical/inventory-monitoring/im-toolbox-freshwater-fish/im-toolbox-freshwater-fish-passive-nets-fyke-nets.pdf.
  5. Lyon, J. et al. (2010) ‘The effect of water level on lateral movements of fish between river and off-channel habitats and implications for management’, Marine and Freshwater Research, 61(3), pp. 271–278. doi: 10.1071/MF08246.
  6. Portt, C. B. et al. (2006) ‘A review of fish sampling methods commonly used in Canadian freshwater habitats. Canadian Technical Report of Fisheries and Aquatic Sciences 2604 Fisheries and Oceans Pêches et Océans Canadian Technical Report of Fisheries and Aquatic Sciences’.
  7. https://seafish.org/gear-database/gear/fyke-net/.
  8. http://www.fao.org/fishery/geartype/226/en.
  9. https://www.doc.govt.nz/globalassets/documents/science-and-technical/inventory-monitoring/im-toolbox-freshwater-fish/im-toolbox-freshwater-fish-passive-nets-fyke-nets.pdf.
  10. https://environment.des.qld.gov.au/__data/assets/pdf_file/0021/90741/biological-assessment-sampling-fish-communities-using-fyke-nets.pdf.
  11. https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1110&context=ncfwrustaff.
  12. https://environment.des.qld.gov.au/__data/assets/pdf_file/0021/90741/biological-assessment-sampling-fish-communities-using-fyke-nets.pdf.
  13. https://www.publish.csiro.au/mf/pdf/MF08246.

8. Gallery

*Cellule Migrateurs Charente-Seudre : partnership between Etablissement Public de Bassin Charente (EPTB Charente), le Centre Régional d'Expérimentation Aquacoles (CREAA) and the association « Migrateurs Garonne Dordogne Charente Seudre » (MIGADO).