EN 14757:2005
(Main)Water quality - Sampling of fish with multi-mesh gillnets
Water quality - Sampling of fish with multi-mesh gillnets
This European Standard describes a standardised method for sampling fish in lakes, using multi-mesh gillnets. The method provides a whole-lake estimate for species occurrence, quantitative relative fish abundance and biomass expressed as Catch Per Unit Effort (CPUE), and size structure of fish assemblages in temperate lakes. It also provides estimates, which are comparable over time within a lake and between lakes. This European Standard provides information on sampling routines, data handling and reporting, sampling of fish for age and growth analyses as well as applications and further treatment of data. Selected references in support of this European Standard are given in the Bibliography.
Wasserbeschaffenheit - Probenahme von Fisch mittels Multi-Maschen-Kiemennetzen
Diese Europäische Norm beschreibt ein genormtes Verfahren zur Probenahme von Fischen in Seen mit Multi-Maschen-Kiemennetzen. Dieses Verfahren liefert Daten zur Abschätzung des Artenspektrums im gesamten See, eine quantitative Abschätzung der relativen Artenhäufigkeit sowie der Biomasse, ausgedrückt als Einheitsfang (Catch Per Unit Effort, CPUE) und der Größenverteilung von Fischbeständen in Seen gemäßigter Zonen. Weiterhin liefert sie Abschätzungen, die für zeitliche Vergleiche innerhalb eines Sees und zwischen verschiedenen Seen geeignet sind. Diese Europäische Norm stellt Informationen für routinemäßige Probenahmen, den Umgang mit Daten und deren Protokollierung, die Probenahme von Fischen zur Alters- und Wachstumsbestimmung sowie Anwendungsmöglichkeiten und weitere Datenbehandlung zur Verfügung. Im Literaturverzeichnis sind ausgewählte Arbeiten angegeben, die direkten Bezug zur Anwendung dieser Europäischen Norm haben.
Qualité de l'eau - Echantillonnage des poissons à l'aide de filets maillants
La présente Norme européenne décrit une méthode normalisée pour l'échantillonnage des poissons dans les lacs, à l'aide de filets maillants multimailles. La méthode fournit une estimation, à l'échelle d'un lac, de l'occurrence des différentes espèces, de leur abondance relative, numérique et pondérale, exprimée en capture par unité d'effort (CPUE), et de la structure en taille des peuplements de poissons dans les lacs tempérés. Elle fournit également des estimations comparables dans le temps au sein d'un même lac ou entre plusieurs lacs. Elle donne aussi des informations concernant les routines d'échantillonnage, le traitement et la communication des données, l'échantillonnage des poissons en vue de l'analyse de l'âge et de la croissance, ainsi que les applications et le traitement ultérieur des données. La bibliographie présente une sélection d'ouvrages se rapportant à cette norme.
Kakovost vode – Vzorčenje rib s pomočjo zabodnih mrež (gillnet)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2005
.DNRYRVWYRGH±9]RUþHQMHULEVSRPRþMR]DERGQLKPUHå JLOOQHW
Water quality - Sampling of fish with multi-mesh gillnets
Wasserbeschaffenheit - Probenahme von Fisch mittels Multi-Maschen-Kiemennetzen
Qualité de l'eau - Echantillonnage des poissons a l'aide de filets maillants
Ta slovenski standard je istoveten z: EN 14757:2005
ICS:
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
65.150 Ribolov in ribogojstvo Fishing and fish breeding
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 14757
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2005
ICS 13.060.70; 65.150
English Version
Water quality - Sampling of fish with multi-mesh gillnets
Qualité de l'eau - Echantillonnage des poissons à l'aide de Wasserbeschaffenheit - Probenahme von Fisch mittels
filets maillants Multi-Maschen-Kiemennetzen
This European Standard was approved by CEN on 27 June 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14757:2005: E
worldwide for CEN national Members.
Contents page
Foreword .3
Introduction.4
1 Scope .5
2 Normative references .5
3 Terms and definitions.5
4 Principle.5
5 Sampling design and equipment .5
6 Time series sampling.7
7 Inventory sampling .10
8 Sampling routine.11
9 Data handling and reporting .12
10 Corrections for gillnet selectivity for six fish species.15
11 Estimate of sampling variance.17
12 Sampling fish for age- and growth analysis .18
13 Applications and further analyses.20
14 Limitations and supplementary sampling.21
Annex A (informative) Distribution of benthic multi-mesh gillnets at different depth strata in
lakes with different area and maximum depth.22
Annex B (informative) Example of forms for registration of fish and supplementary data .24
Bibliography.27
Foreword
This European Standard (EN 14757:2005) has been prepared by Technical Committee CEN/TC 230 “Water
analysis”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by February 2006, and conflicting national standards shall be withdrawn
at the latest by February 2006.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
Introduction
This is the second of several European Standards developed for evaluation of the species composition,
abundance and age structure of fish in rivers, lakes and transitional waters. Other standards describe
“Sampling of fish with electricity” (EN 14011) and “Guidance on the scope and selection of fish sampling
methods” (prEN 14962).
In most countries the use of the method specified in this European Standard requires permits from landowners
and national or regional authorities. In many countries permits are also required from authorities for animal
rights and animal welfare demands. Both fish diseases and diseases specific for other organisms, such as
freshwater crayfish, may be spread by placing equipment contaminated with pathogens or parasites in the
lake. The user of this method should check which national legislation is applicable.
WARNING — Persons using this European Standard should be familiar with normal laboratory and
fieldwork practice. This European Standard does not purport to address all of the safety problems, if
any, associated with its use. It is the responsibility of the user to establish appropriate safety and
health practices and to ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this standard be carried
out by suitably trained staff.
1 Scope
This European Standard describes a standardised method for sampling fish in lakes, using multi-mesh gillnets.
The method provides a whole-lake estimate for species occurrence, quantitative relative fish abundance and
biomass expressed as Catch Per Unit Effort (CPUE), and size structure of fish assemblages in temperate
lakes. It also provides estimates, which are comparable over time within a lake and between lakes. This
European Standard provides information on sampling routines, data handling and reporting, sampling of fish
for age and growth analyses as well as applications and further treatment of data. Selected references in
support of this European Standard are given in the Bibliography.
2 Normative references
The following referenced documents are indispensable for the application of this European Standard. For
dated references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
prEN 14962:2004, Water quality — Guidance on the scope and selection of fish sampling methods
3 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in prEN 14962:2004 apply.
4 Principle
The sampling procedure is based on stratified random sampling. The sampled lake is divided in depth strata
and random sampling is performed within each depth stratum. Sampling of benthic fish is performed with
specially designed multi-mesh gillnets which are 30 m long and 1,5 m deep. The gillnets are composed of 12
different mesh-sizes ranging between 5 mm to 55 mm knot to knot following a geometric series. Gillnets used
for sampling pelagic fish are 27,5 m long and 6 m deep, with the smallest mesh-size being 6,25 mm. The
sampling effort needed to allow detection of 50 % changes in relative abundance between sampling occasions,
range between 8 gillnets per night (efforts) for small, shallow lakes, up to 64 efforts for lakes of about 5 000 ha.
When less accurate estimates of abundance are needed, an inventory sampling procedure may be used,
thereby reducing the number of efforts needed.
5 Sampling design and equipment
5.1 Sampling design
Fish are not randomly distributed over a lake. Depth distribution varies between fish species and with the
ontogeny of the fish. The horizontal distribution may also be influenced by habitat heterogeneity. Neither is the
distribution constant over the year, but will vary with temperature and season.
To cope with this uneven distribution a stratified random sampling design is used. The lake is stratified in
depth strata and a random sampling is performed within each depth stratum. Each gillnet is placed to
represent an independent sample of the fish assemblage. By randomising the location of each gillnet within
each depth stratum and by randomising the angle of the gillnet in relation to shoreline, an independent sample
of the fish in each stratum will be achieved. Randomisation is performed prior to fishing by the aid of depth
maps and a co-ordinate grid. If needed, the angle of the gillnet in relation to the shoreline shall be adjusted so
that the gillnet is within the corrected depth stratum.
5.2 Benthic gillnets
The multi-mesh gillnets have been designed for catching all types of freshwater fish species. Each gillnet is
composed of 12 different mesh-sizes ranging from 5 mm to 55 mm (knot to knot). The mesh-sizes follow a
geometric series, with a ratio between mesh-sizes of about 1,25. All gillnets have the same order of mesh
panels (see Table 1).
If experience has shown that large fish of certain species (e.g. bream, pike, tench) are difficult to catch with
the mesh sizes shown in Table 1, then these may be modified as required. However, a note on such
modification shall be given in the report (fishing protocol).
Table 1 — Mesh-size distribution (knot to knot) and thread diameter in the multi-mesh benthic gillnets
Mesh no Mesh size Thread diameter
mm mm
1 43 0,20
2 19,5 0,15
3 6,25 0,10
4 10 0,12
5 55 0,25
6 8 0,10
7 12,5 0,12
8 24 0,17
9 15,5 0,15
10 5 0,10
11 35 0,20
12 29 0,17
The gillnets shall be made out of homogeneous, uncoloured nylon. Each gillnet shall be 30 m long and 1,5 m
deep. Each mesh panel shall be 2,5 m long and mounted on a 30 m long buoyancy line (with a recommended
linear density in water of 6 g/m), and a 33 m long lead line (recommended linear density in air 22 g/m and in
water 9,9 g/m) made out of plastic in light grey colour. The diameter of the thread varies between 0,10 mm for
the 5 mm mesh, to 0,25 mm for the 55 mm mesh (Table 1). All mesh panels are commercially available. The
hanging ratio is 0,5 for all mesh sizes.
5.3 Pelagic gillnets
Each pelagic gillnet is 27,5 m long and 6 m deep. Gillnets used for sampling pelagic habitats are similar to the
benthic gillnets with the following exception. The smallest mesh (5 mm) has been excluded, because it has
not been possible to manufacture 5 mm panels mesh as deep as 6 m. The buoyancy line is 30 m, and the
lead line is 45 m with a hanging ratio of 0,5. The weight of the lines may be different from that of the benthic
nets. The pelagic nets are divided in half at 3 m depth by inserting a darkish colour (e.g. made of spun nylon)
in order to separate the catches below and above 3 m depth.
5.4 Time for sampling
The result of fish sampling using passive gears is highly influenced by water temperature, life history and time
for spawning of specific fish species. Therefore, the sampling period has to be chosen in such a way that each
single species is neither over nor under-represented in the catch. This means that the optimal sampling period
may differ between countries and regions. To minimise between-year variation, due to differences in activity
between species, the sampling period should be defined for each lake or region to be sampled in order to
make sampling data between different lakes and years comparable.
For instance, in northern Europe the sampling should normally take place between July 15 and August 31.
During this period most freshwater fish species living in lakes do not spawn, and the epilimnion temperature
usually exceeds 15 °C in most non-alpine areas. Due to decreasing epilimnion water temperature in
September it is not recommended to prolong the sampling period as the catch may decline substantially when
epilimnion temperature drops below 15 °C. Some species, and especially cyprinids, may also change their
behaviour during autumn, thereby affecting the representativity of the sampling. When it is known that the
catch is good for the species present even at temperatures down to 10 °C, then the sampling season may be
extended until September 15.
5.5 Sampling perio
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