seine netting



A DAY OUT SEINE NETTING. Photographs and descriptions of a troublesome day netting a small lake for carp.

Overview
A seine net can be of anything from 10 to 1200 metres in length and visually looks similar to a standard anglers landing net. They are weighted at the bottom with counteracting floats at the top resulting in a net wall within the water. The seine is one of the main tools applied in fishery management and they have a multitude of uses. Mainly they are used to remove fish from a water body for either stock reduction or survey purposes. Alternatively, the smaller nets can be used as stops in ponds, raceways or when electrofishing.
 

Design and construction
A seine is made up of panels of netting stitched to make a rectangular shape. Top and bottom are ropes that run the length of the net; the panels are tied to these ropes with heavier gauge string. It is important the base of the net is in continued contact with the lake bed therefore weights are required to keep the buoyant net down. Two options are available - lead rope or barrel leads. I have little experience of lead rope but others have led me to believe it does not have the efficiency of barrel leads. Barrels can be from 1-3oz in weight, but commonly the 2oz leads are used as the larger size does tend to cause problems by digging in to heavy silt or sand. A lead is positioned below every cork (float) throughout the length of the net. The choice of corks and leads is solely down to the user and the site conditions.

The choice of net mesh is extremely important. All nets are now knotless as this type of mesh is much kinder to delicate fish species. Certain considerations are needed when deciding on the mesh size of the seine net. Firstly is the target species and potential fish size. Nets with too larger mesh will end up acting as gill nets, an unwanted and ugly result. Although most gill netted fish survive if carefully removed this takes time and will certainly reduce the efficiency of the netting operation. Conversely, if the mesh size is too small the net will collect large quantities of silt resulting in problems when retrieving. Also a large area of net with small mesh can act as a solid wall, something very difficult to pull through water. Usually 9-12mm mesh is used for the main net section with a couple of panels in the centre of 5-6.5 mm mesh; this is the landing area when the net has been fully retrieved. On very large nets the wing sections can have a mesh size of up to 22mm.

Seines can vary in size dramatically. Whilst netting with MEM Fisheries Ltd. I believe we have used England's largest inland nets encroaching 1200 metres in length. A seine of this magnitude, if used correctly, is capable of netting 229183 square metres (57 acres) in one hit. Alternatively, a standard length seine of 200 metres can net approximately 6366 square metres (1.57 acres), but net manipulation can drastically increase this area; techniques will be discussed later.

Applications
Seines can be applied to almost any water body or type. They tend to be most successful on lakes and reservoirs where large expanses of water are clearly visible as this allows plenty of working area. As nets are pulled up bank sides the more area behind the waters edge, the easy the job becomes. Canals can be dragged down with smaller seines and rivers can be surveyed using two or more nets applying wrap around techniques.

Netting techniques
More commonly a seine is laid straight from a boat so this needs to be of the correct size to suit the net. The seine is laid in a horseshoe shape starting and ending on the same bank; it is important that when fed the leads are laid furthest from the bank as this is the natural way the net is retrieved; incorrectly laid the net is prone to rolling hence reducing the depth of the net.

Once set the net should be pulled from each end in an alternate procedure of short lengths trying to keep the landing area in the centre. It is imperative that only the cork line is used to retrieve the net and under no circumstances should the lead line be touched; this will naturally follow the cork line in. The pull will close the net to the centre leaving the discarded net each side of the landing area. When almost in the leads are pulled from underneath leaving a bowl shaped tightly secured from the outside water.

Unfortunately it is rarely as simple because any obstruction in or on the lakebed will hinder the ease of pull and shape of the net. Snags commonly create problems, sometimes resulting in large areas of ripped net. The larger area netted the increasing problems may result, essentially it's trial and error with the errors sometimes being very costly.



Inherent problems
Unfortunately, many obstacles are put in the way of a successful netting procedure. The substrate has a huge influence on the net retrieval and can cause problems with regards to total net weights. The ideal lake bed consists of solid clean clay tapering slowly to the centre of the pool, but as many fisheries managers and anglers will know this rarely exists. On many occasions throughout a netting the silt needs to be removed by either walking, if shallow enough, or accessing by boat. The net is tightened and the leads are quickly lifted then dropped resulting in a 'dumping' of excess material. This does run the risk of fish escape, but if the net is of a weight exceeding the retrieval capability there is no other option. More commonly the silt is pulled to the bank and fish, if in sufficient quantities, will wash the material through.

Snags are an obvious problem and can result in net damage. Again the net can usually be removed with careful manipulation of the leads. Islands can cause problems in smaller lakes, but well organized teams can lay smaller stop nets hence splitting the pool into sections. This procedure does require experience if to be carried out successfully. Holes in the lake bed can hold large quantities of fish and if the pool is of a deep nature there is no solution to this problem.

Weed in large quantities will make netting impossible. Canadian pondweed is the worst offender as it entangles and then rolls the net top to bottom. Unfortunately we have yet to find a good system to counteract this problem so if your pool has a weed problem it will then also have a netting problem. Finally, large vertical shelves around the lake margin tend to lift lead lines to such an extent that all fish will escape before landing. Time and patience is the only solution with a very slow net retrieval being the best option.


Fish Reactions
Fish species have different reactions to a seine net. Bream will shoal in the centre and follow the net in until they are caught easily. Roach and rudd will also shoal, but tend to find escape through the net mesh. Carp, being more aggressive, will bury underneath the leads and if escape is successful become increasing harder to catch in continued netting. In warmer months carp go for the easier option, straight over the cork line. Tench will follow carp if in multi species fisheries or if on there own will try to gain escape late in the net landing. Pike charge into net sides but rarely find an escape route.
 

Conclusions

This has been a brief overview of seine netting and I hope it has given the reader an insight into the procedures and problems. The most important message to potential netsman is 'know your lake'. Every detail should be investigated before a netting is undertaken and the more planning that is done, the more impressive the result.

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