Fishing nets - Passive fishing gear


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RNDr. Marie Prchalová, Ph.D.
RNDr. Marie Prchalová, Ph.D. I work at the Institute of Hydrobiology (Biology Centre AS CR, v.v.i., Fish Ecology Unit). My research focuses on fish ecology in reservoirs, especially fish spatial distribution. In addition, I also work on gillnet sampling methodology of fish communities. I am an active contributor to the development of standardized sampling and evaluation techniques for fish communities for the European Water Framework Directive and I assist in updating the European Standard EN 14757 (“Water quality – sampling of fish with multimesh gillnets”). In the past, I have participated in the Spanish Ministry of Environment’s project on the calibration of sampling methods in Spanish reservoirs. I also contributed to projects of tropical fish ecology in reservoirs of Thailand, the Philippines, Sri Lanka and Puerto Rico, and was involved in fish community research in Dutch reservoirs, which was financed by the Dutch drinking water company.

In my work I analyze gillnet sampling methodology of fish communities and am an internationally respected and cited author. I am also involved in reviewing scientific manuscripts prior to their acceptance to journals. I was the principal researcher of two projects which dealt with gillnet methodology. Together with my colleagues, I have published many scientific articles on gillnet sampling of fish communities. For example, we examined the underestimation of small fish and overestimation of large fish in gillnet catches (Prchalová et al., 2008 and 2009). Gillnet catches were also used to describe fish activity in detail (Vašek et al. 2009, Prchalová et al. 2010). A model of gillnet sampling was developed and we suggested a new way to express gillnet catches. This model avoids the influence of changes in fish activity, fish falling out of gillnets during exposure and saturation of gillnets (Prchalová et al. 2011 and 2013). In Prchalová et al. 2012, the advantages and disadvantages of catching small tropical fish Dorosoma petenense into gillnets and trawls are discussed. Gillnets were also used in research estimating the abundance of fish in the blind zone of a hydroacustic survey (Tušer et al. 2013). Based on sections of the entangled gillnet where the eel attacked fish caught in gillnets, I described the estimation of the European eel (Prchalová et al. 2013). Recently my work entails appropriate gillnet sampling design, with the calibration of gillnet catches according to known fish communities and with differences in gender-dependent gillnet catchability of several fish species. All my research is based on using gillnets made by the Pokorný-sítě company. We collaborate in development of the new gillnet types or in innovation of the sampling design.


Prchalová, M., Kubečka, J., Říha, M., Čech, M., Jůza, T., Ketelaars, H.A.M., Kratochvíl, M., Mrkvička, T., Peterka, J., Vašek, M., Wagenvoort, A.J., 2013. Eel attacks - A new tool for assessing European eel (Anguilla anguilla) abundance and distribution patterns with gillnet sampling. Limnologica 43, 194-202.

Prchalová, M., Peterka, J., Čech, M., Kubečka, J., 2013. A simple proof of gillnet saturation. Boreal Environment Research 18, 303-308.

Tušer, M., Prchalová, M., Mrkvička, T., Frouzová, J., Čech, M., Peterka, J., Jůza, T., Vašek, M., Kratochvíl, M., Draštík, V., Kubečka, J., 2013. A simple method to correct the results of acoustic surveys for fish hidden in the dead zone. Journal of Applied Ichthyology 29, 358-363.

Prchalová, M., Neal, J. W., Munoz-Hincapié M., Jůza, T., Říha, M., Kubečka, J., 2012. Comparison of gillnets versus fixed-frame trawl for sampling threadfin shad in tropical reservoirs. Transactions of the American Fisheries Society 141, 1151-1160.

Prchalová, M., Mrkvička, T., Peterka, J., Čech, M., Berec, L., Kubečka, J., 2011. A model of gillnet catch in relation to the catchable biomass, saturation and soak time. Fisheries Research 107, 201-209.

Prchalová, M., Mrkvička, T., Kubečka, J., Peterka, J., Čech, M., Muška, M., Kratochvíl, M., Vašek, M., 2010. Fish activity as determined by gillnet catch: A comparison of two reservoirs of different turbidity. Fisheries Research 102, 291-296.

Prchalová, M., Kubečka, J., Říha, M., Mrkvička, T., Vašek, M., Jůza, T., Kratochvíl, M., Peterka, J., Draštík, V., Křížek, J., 2009. Size selectivity of standardized multimesh gillnets in sampling coarse European species. Fisheries Research 96, 51-57.

Vašek, M., Kubečka, J., Čech, M., Draštík, V., Matěna, J., Mrkvička, T., Peterka, J., Prchalová, M., 2009. Diel variation in gillnet catches and vertical distribution of pelagic fishes in a stratified European reservoir. Fisheries Research 96, 64-69.

Prchalová, M., Kubečka, J., Říha, M., Litvín, R., Čech, M., Frouzová, J., Hladík, M., Hohausová, E., Peterka, J., Vašek, M., 2008. Overestimation of percid fishes in gillnet sampling. Fisheries Research 91/1, 79-87.


What was enmeshed in gillnet is likely to become a filet.

The advantages of gillnets:

These advantages make gillnets one of most used nets for the fish community research

The exceptional standing of gillnet data in Europe

In our contemporary and globalized world, the crucial issue is the use of a singular method which enables data comparison among countries. The European Committee for Standardization (CEN), consisting of experts from 33 European countries, is the most important such organization in the European sphere. The norms produced by CEN are accepted by individual member countries as national norms. The most important document in the field of fish sampling is the norm CEN14962 “Water quality — Guidance on the scope and selection of fish sampling methods”, which also exist in Czech as ČSN EN 14962 (757710) Water quality — Guidance on the scope and selection of fish sampling methods . The norm describes the process to choose the appropriate evaluation method for fish communities in rivers, lakes and brackish waters. Each method is also briefly described and the recommendation for each ecosystem is included in the norm. For example, with respect to the goal of monitoring, sampling by beach seining is recommended for use in inshore areas of lotic fresh waters, while trawling, drifting gillnets or traps are the recommended sampling method for offshore areas. In lentic waters beach seining is recommended for sampling inshore areas, while offshore areas

should be sampled with traps, and in the case of large, deep water bodies purse seining and trawling can be used. Nets have a broad range of applications with which no other sampling method can compare.

Gillnets as the main sampling method

Currently the most important legislative document in the field of EU water policy is the Water Framework Directive (2000/60/ES). This document instructs member countries to develop a national methodology to evaluate the ecological state of natural water bodies and the ecological potential of strongly modified and man-made water bodies. In the Czech Republic, the methodology for evaluating the biological components of fish in reservoirs and artificial lakes was based on the data obtained from gillnet samples (Borovec et al. 2014). The next step is the process of inter-calibration where member countries are grouped according to their geographic region to compare and discuss the various methodologies. The Czech Republic belongs to the Central and Baltic region (C/B GIG). Experts from other countries in the region use gillnet sampling to obtain information about fish communities. Concurrently, the gillnet sampling is standardized by European Norm CEN 14757 Water quality - Sampling of fish with multi-mesh gillnets (Czech version ČSN EN 14757).

Europe-wide attempts to unify the evaluation of fish communities into the WISER project ( resulted in the formation of the Europe-wide database of fish catches (Causeé et al. 2011). The data characterizing lakes include exclusively gillnet catches, which in the case of the Czech Republic were made by the Pokorný – Sítě company. The first results were based on benthic gillnet catches solely from natural lakes (e.g. Argillier et al. 2013, Brucet et al. 2013). Further research will also focus on artificial lakes and on the sampling of pelagic fish communities.


Innovations of scientists from the Institute of Hydrobiology BC AS CR, v.v.i. in České Budějovice


Innovations in the deployment of gillnets:

Description of innovations:

Descriptions of the innovations are included in the book about the methodology of monitoring fish communities in lakes and reservoirs (publisher Institute of Hydrobiology, BC AS CR, v.v.i., collective authorship J. Kubečka, J. Frouzová, T. Jůza, M. Kratochvíl, M. Prchalová, M. Říha, 64 pp., in Czech), which also includes descriptions about trawling, beach seining, electrofishing and hydroacoustic methodology.

The table shows the mesh order mesh size and thread diameter in gillnets according to Norm EN 14 757

The mesh order in gillnetThe mesh size in mmThread diameter

Table shows the mesh order, the mesh size and thread diameter in large mesh gillnets according to innovations of scientists from the Institute of Hydrobiology BC AS CR, v.v.i. in České Budějovice

The mesh order in gillnetThe mesh size in mmThread diameter

The size characteristics of 12-mesh gillnet:

The sizes and shape of the gillnet

Gillnet height

The size characteristics of 4-mesh gillnet:

Two basic gillnet types are available – benthic and pelagic

The benthic gillnets

The pelagic gillnets

The epipelagic gillnets – fully floating
The mesopelagic gillnets
The bathypelagic gillnets

Placement of the gillnet in the water column

Placement of benthic and bathypelagic gillnets in lake and reservoir habitats

Gillnet finder

Keep in mind the following ethical standards:

Instructions for use:
Instrucitons to extricate stucked gillnet finder:

use of pelagic and benthic 12 mesh size gillnets (for mesh sizes see table above, length 12 x 2.5 m, height 1.5 - 4.5 m)