Fishing method of tuna

There are two ways to catch tuna. One is longline fishing, which mainly catches bluefin tuna, Ma Su tuna, bigeye tuna, yellowfin tuna and albacore tuna. It lives in deep water and weighs more than 20kg.

There are three types of longline fishing: floating longline fishing, bottom longline fishing and middle longline fishing.

Tuna longline fishing tackle is mainly composed of trunk line, support line, float, floating line and fishing hook. That is, hang a few support lines with hooks on the extended trunk line to catch tuna. A number of floats are tied to the dry rope, and the length of the floating rope and the supporting rope between the dry rope and the floats plays a role in adjusting the fishing water layer. The hook needs to be loaded with Er material. Er materials mainly include frozen saury, squid, sardines and mackerel. According to the feeding characteristics and vertical law of tuna, it is best to choose 3-4 am.

With the delay of the rise and fall of moonlight, the pay-off time will also be delayed. If it is released too early, the bait will be swallowed by other fish before the tuna is eaten.

Pay-off direction should be cross flow or oblique flow. Generally speaking, tuna likes to feed against the current. One is that the pay-off direction is perpendicular to the water flow direction. This method has a large cross section, which can provide reference for the next pay-off width. A better way is to form a "V" shape perpendicular to the current, which can increase the chance of the same fish being hooked.

The line speed should be 8-9 knots, which can be observed by the guide. For example, the speed of the line can be reduced accordingly to make the line deeper.

When paying off the line, it is not a big problem for two ships to cross, but don't fish in parallel with other ships within 5 nautical miles, otherwise the lines may get tangled. When paying off, keep the starboard side exposed to wind or current, and the bait should be thrown upward, otherwise, the branch line will take the main line, and the hook will not extend effectively, which will affect the fishing effect. Due to the phototaxis of tuna, the catch will increase on a better moonlight night. On the contrary, it will decrease. It's not that there are no fish in the dark and windy month, but because of the weak light intensity, the floating water layer of small fish can't reach the original water layer. In addition, when it is dark, the fishing line forms a big slope because of the relatively fast water flow, and the hook can't reach the original depth, so the fishing effect is very poor.

The following methods can be taken to overcome this problem:

Extended floating chord length ratio

Lengthening the branch line length, changing the floating-sinking ratio and increasing the lead drop.

Avoid the rapids and find a fishing ground with slow water flow.

Another method is surface fishing gear fishing, including purse seine fishing, rod fishing and dragline fishing, to catch tuna perched on the ocean surface. The main fishing species are small yellowfin tuna, bigeye tuna and bonito, and the weight range is 5- 10 kg.

According to the latitude of tuna in different months, the position of the central fishing ground is determined.

On the chart, look for sea areas with great changes in water depth and reciprocating flow. In these sea areas, due to the great change of water depth, it is easy to form upwelling, which will impact plankton and small fish and shrimp to float up and form tuna feeding grounds.

According to the water temperature, current and other conditions, the central fishing ground is determined by comprehensive analysis. Usually, it is possible to catch tuna when the surface water temperature reaches above 27℃. Specifically, the water temperature suddenly changes, tuna predation stops, the surrounding water temperature changes slightly, and fish swim quickly. The current flows through the undersea mountains, which leads to the upwelling of fishing grounds, which are often high-producing areas of yellowfin tuna.

We should pay close attention to the changes of marine life. The sea where seabirds are dense, the sea where whales and dolphins float out, and the water where small fish flock are often places where tuna are dense.

Tuna floats for food at night, especially on a moonlit night. "Moonlight Night" can use some live goggles as bait to lure tuna to prey, or add luster to achieve the same effect.