Nylon Netting

Nylon netting is one of the most common and versatile types of netting used. It is very strong, easy to work with, easy to repair, and is resistant to most chemicals and water. This netting is widely used in commercial fishing for seines, pound nets, hoop nets, trap nets, as well as industrial and sports nets.

The netting in composed by meshes in different dimensions and 3 different shapes: Diamond, Square and Hexagonal

The square mesh netting is one of the most common used and well known selective devices. In this the diamond mesh is turned through 45 degrees to the water flow thereby ensuring the meshes remain fully open throughout the fishing operation, allowing for the release of small fish.

In a standard trawl constructed from normal diamond mesh, without a square mesh panel fitted, the mesh opening, in the area of the fishing circle, will only be about 30 – 40% of the mesh length. This means that a mesh of 100mm inside mesh will only be open to about 30 -40mm at its widest point, not a very big area for fish to escape from.
The meshes further down the net may only be open to about 20% of the mesh length (20mm for 100mm mesh or 16mm for 80mm mesh) in the codend and extension this figure can be as low as10% of the mesh length. With modern high powered vessels towing the gear faster and at a more consistent speed this mesh opening will be maintained throughout the duration of the tow in all but the poorest weather. There is not much chance of escape for small fish.

The standard square mesh panel is 3 metres long (2m for lower powered vessels) fitted at the end of the tapered section of the trawl or in the parallel extension. In this area of the cross section of the trawl will be of an oval shape with a maximum width of about 500mm and a height in the region of 350mm allowing most of the fish exposure to the panel but in a very confined space. However with the modern vessels towing in the region of 3 knots a fish is only exposed to the square mesh panel for about 2-3 seconds. This is not much time for a fish that is already fatigued from being herded into the trawl and stressed from travelling down from the mouth of the trawl to find the escape route and escape through it.

The effectiveness of a square mesh panel at releasing small fish can vary depending on many criteria such as the clarity of the water, daylight or darkness, depth of water, colour and type of netting used, twine thickness, how it is fitted into the trawl, speed of water flow through the trawl, size of fish and whether the fish are passing down the trawl in groups or as a steady flow of individuals. By using larger mesh sizes, thinner twine or increasing the area of a square mesh panel more small fish will be released.

Many fishermen are already using larger mesh than required for regulation.

It is not so easy to decrease twine thickness due to the need to maintain strength and prevent stretch. More recently many skippers have been experimenting with a second square mesh panel, of much larger mesh size further forward in the trawl in an attempt to reduce their discard rates. Some have tried fitting square mesh as large as 300mm mesh almost right up to the fishing circle of the trawl but have found that although these do work to a certain extent they are not as good as expected, only releasing about 30% of the haddock and whiting and having very little effect on cod catches.
This could be for several reasons. This fish are stimulated by the approaching bosom of the trawl to rise up and attempt to escape this danger by swimming ahead and over the headline. Generally it is only the fish that are in close proximity to the top large square mesh panel as they pass down the trawl that will attempt to escape through it. The fitting of these square mesh panels closer to the front of the trawl can require a bit of thought as the diamond meshes in this area will be more open than in the extension. Estimating the actual mesh opening, and there by the mesh length at this opening can be extremely difficult. There is no easy solution as the actual mesh opening will vary with the design of trawl and several other criteria will also have an influence on it. If there is a length differential between the diamond and the square mesh it could well affect the fishing efficiency of the trawl.

Knotless net has gone mainstream.

Without knots, netting does not have high spots to abrade on stern ramps, ship rails, net rollers, or even rough bottom. In the case of purse seines, the netting shoots very smoothly as there is no inter-knot friction. Knots can tighten or distort throughout the life of netting, dramatically changing mesh size. Hollow braided twines can hold sediment which not only wears on the twine from the inside, but also changes mesh size.

Luxsol® netting maintains nearly 100% of its original mesh size throughout the life of the product, and has no knots to distort.

The aggregate resistance existing of knots in standard netting is considerable and becomes an important factor where water flow through the mesh is a concern.
Luxsol® netting is very kind to fish with less bruising and abrasion from knots. This fact has been proven in many of the world’s fisheries where product quality cannot be compromised.