Weihai Huaxing Nets provide high quality Tuna Cage Nets Purse Seine Fishing for all over the world. All the above dimensions can be customized.

Product Features 

*Material: nylon

*Mesh size: 100mm full

*Type: Braided knotted, knotless

*Colour: Black, white

*Tear resistant mesh netting

Overview

Tuna purse seining involves surrounding tuna shools with a net, impounding the fish by pursing the net, and drying up the catch by hauling the net so that the fish are crowded in the bunt and can then be brailed out.

Species Environment

As the purse seine catches fish above the thermocline, fish tuna and tuna-like fish inhabit in the surface and sub-surface zone (mixing area) are the target of this technique. They are, in tropical waters, juvenile yellowfin, juvenile bigeye and skipjack, together with some small tuna-like fish such as frigate tunas, bonitos, etc. Those fish are generally feeding baitfish near surface. In temperate waters, they catch either small juvenile bluefin tuna when they are feeding on baitfish or large bluefin tuna while they surface for spawning activities. Also in temperate waters, purse seine is occasionally used to harvest albacore, generally during night when fish come to surface for feeding.

Fishing Gear

The industrial purse seine gear is a large net which is used to encircle the school of tunas and closed at the bottom to entrap them. The synthetic net measures 1 500 to 2 000 m long and 120 to 250 m depth. The size of the mesh is usually around 120 mm stretched mesh. The top of the net is mounted on a floatline and the bottom on a leadline which, usually consists of a steel chain with steel rings, known as “purse rings”, are attached below the chain; the purse line which run through the purse rings is made of steel and allow the pursing of the net. There are smaller purse seine gears used for less industrialized fishing near coastal areas, mostly targeting small tuna-like fish, such as frigate tunas, and bonitos. Those fishing is seasonal and the same gear is used for other pelagics such as sardine and anchovies.

Vessel Overview

Tuna purse seiners vary considerably in size. Industrial tuna purse seiners are usually large vessels which length ranges between 45 and 85 m, sometimes over (up to 100-110 m). Those seiners are facilitated with a large skiff, often with a few speed boats, and with a helicopter. Also equipped with a brine freezing fish wells. In coastal areas, smaller purse seiners also operate, sometimes on juvenile tuna species or tuna-like fish. The same boats are multi-purpose, including fishing for small pelagics (sardine, jacks, mackerels etc.) and seasonally fish for tunas. The size varies from 20 to 50 meters. All purse seiners are equipped with a power block to purse the lead line after fish are inside of the net. In some area, paired seiners were used of the size of about 300 to 400 GT. But this fishing methods has been reduced if still exist.

Handling Mode

Storage of tuna once it is caught presents a problem, for the size of the fish is large. Some vessels are equipped to bulk-freeze the catch, but the commonest method is to keep the fish in refrigerated brine tanks (brine at 0 °C), which form much of the lower parts of the hull and are equipped with batteries of seawater pumps for circulation. In the industrialized purse seiners, the tunas are preserved in wells of 20 to 40 metric tonnes each, (total 800 to 2 000 metric tonnes) with brine freezing at -20 °C. In the more artisanal purse seiners, tuna are generally kept in iced seawater.

Fishing Environment

In general the tuna purse seines are used to capture (large pelagic) fish aggregated and swimming not too far from the surface (mixing zone above thermocline) in the high-sea waters, as well as in the near coast waters. Aggregated resources up to a maximum of 300 m depth, but practically at depth less than almost 150 m depth and mostly less than 60-70 m are targeted.

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