Fishing nets - Handling equipment
Plankton nets
Plankton nets are used for catching and sampling plankton of all sizes and species.
Samples are carried out for research or for harvesting plankton for feeding early stages of fry of all fish species.
Plankton nets can be separated into
Plankton nets with a handle - the net is mounted to a metallic frame with a handle
Plankton cast nets - the net is mounted to a metallic frame and is supplemented by a string bin
Apstein plankton nets - similar to plankton cast nets, however, they include a larger area of netting and a cone-shaped extension ensure a superior catch of plankton
Tow plankton nets - net is mounted to big metallic frame and the net is towed by boat
Static drift plankton nets - nets with or without a frame that are fixed in the current
Plankton nets with handle, hand plankton net
Plankton nets with a handle are used for catching plankton from a boat or from the shore. They are used to sample all sizes and types of plankton for research and also for feeding.
The netting is made from precise fine polyamide material (material where the mesh size is guaranteed - meshes are fixed in order not to shift). The net is mounted to a metallic frame of round shape with a handle.
The frame is from a steel wire with an 8 mm diameter. A metallic tube is welded to this frame and serves as a holder for a handle.
The netting can vary in mesh sizes, standard depth of the net is 70 cm. The upper hem is made from polyamide cloth and the lower hem is formed in order to gather plankton in the middle of the net bottom. The shape of the net is a U with the same width of the upper and lower hem, or V with the net narrowing towards the lower hem.
| Perimeter | Shape | Wire diameter | Mesh size (mm) | Depth |
|---|---|---|---|---|
| 120cm | round | 8mm | 0,04, 0,1, 0,2, 0,24, 0,3 | 70cm |
Cast plankton net
Cast plankton nets are used for catching samples of all sizes and species of plankton from vertical as well as from horizontal profiles of the water column. Catching can be carried out from the shore or from a boat.
The netting is made from precise fine polyamide material (material where the mesh size is guaranteed - meshes are fixed in order not to shift). The net is mounted to a metallic frame of round shape and supplemented by bin and string of 3 mm in diameter. The net has a metallic outlet faucet, which is used also as a weight during net casting or sinking.
Cast plankton nets
| Mouth diameter/depth | Fine netting PA | Hem height | Built bin |
|---|---|---|---|
| 20/40cm 30/50cm 40/60cm | 0,04, 0,1, 0,14, 0,2, 0,24 0,30, 0,34 mm | 5cm | 20m |
Cast net bag
The cast net bag is essential accessory for the cast net. The bag serves as a net cover, for net transportation and also as a storage bag for samples.
Apstein plankton net
Apstein plankton net is supplemented by cone-shaped metallic extension (Apstein's extension) that reduces water turbulences in front of the net mouth. The net area is bigger than in common cast net.
This net is used for assessment of zooplankton abundance in a given water column and usually it is used for vertical hauls. The net can be supplemented by constricting loops in order to close the net for separate samples only from given depth layers of the water column (closing net SEĎA).
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The netting is made from precise fine polyamide material (material where the mesh size is guaranteed - meshes are fixed in order not to shift). The upper net hem is strengthened by polyamide cloth in a shape of an opposite cone. In the middle of this cone, tiny rings are stitched where the second leading line goes through. Upper leading frame is made from thick steel wire and other rings with a leading line are connected to this frame.
An outlet faucet is located on the lower hem of the net.
Tow plankton net
The tow plankton net is used for catching larger amounts of plankton and for fry samples.
The net is usually towed by a boat.
The netting is made from precise fine polyamide material (material where the mesh size is guaranteed - meshes are fixed in order to do not shift) or from tulle (material from firm polyester - meshes are fixed in order not to shift; mesh size 2 mm). The upper hem is strengthen by tough cloth and mounted to a metallic frame of round shape by three binding loops, which are connected to a towrope. An outlet sleeve is at the lower hem of the net, where a collecting container can be mounted. Without the container, the sleeve is enwrapped during the haul.
The netting can be divided into strips of various mesh sizes for better water permeability.
| Mouth diameter/depth | Fine netting PA / tulle | Hem height | String bin |
|---|---|---|---|
| 1m/2-3m | 0,2, 0,24 0,30, 0,34 , 0,4, 0,5mm/2mm | 10cm | Lano 6mm |
Static drift plankton net
The static drift plankton net is used for harvesting plankton in large amounts for feeding fishes.
The best location for the net is a place with high current and high amounts of drifting plankton (outlet conduits, overflows, etc.)
The netting is made from precise fine polyamide material (material where the mesh size is guaranteed - meshes are fixed in order not to shift). The net has cylindrical shape with hems thickened by tough cloth. In some cases, one hem is supplemented by loops for mounting the net to the frame. Caught plankton gathered in the back part of the cylinder, which is tied firmly.
Net diameter, length and size are adjusted to local conditions.
The quality and reliability of plankton nets made by Pokorný-Sítě Company was proven in sampling zooplankton for following scientific works:
Devetter M, Sed'a J
Regulation of rotifer community by predation of Cyclops vicinus (Copepoda) in the Rimov Reservoir in spring
INTERNATIONAL REVIEW OF HYDROBIOLOGY 91 (1): 101-112 2006
Devetter M, Sed'a J
Decline of clear-water rotifer populations in a reservoir: the role of resource limitation
HYDROBIOLOGIA 546: 509-518 SEP 1 2005
Machacek J, Sed'a J
Life history response of Daphnia galeata to heterogeneous conditions within a reservoir as determined in a cross-designed laboratory experiment
AQUATIC ECOLOGY 41 (1): 55-66 MAR 2007
Jaromir Seda, Adam Petrusek, Jiri Machacek, and Petr Smilauer
Spatial distribution of the Daphnia longispina species complex and other planktonic crustaceans in the heterogeneous environment of canyon-shaped reservoirs
JPR Advance Access published on May 14, 2007
J. Plankton Res. 2007 29: 619-628; doi:10.1093/plankt/fbm044