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Sea Fishing Current Knowledge

Often talking about fishing skills, today we talk about sea fishing current knowledge.

First, the Kuroshio Current

Fishing in the marine environment must naturally take into account changes in ocean currents, and the ocean currents that have the greatest impact on us are the Kuroshio.
Ocean current is a form of seawater flow, which has a wide range and stable nature, and will have a major impact on the environment, climate, ecology and even culture of the region where it passes.

Why does sea water flow? There are several reasons for this:
1. Wind blows.
The surface of the earth has a generally fixed planetary wind system (a global wind system with a range of influence) and a relatively unfixed, localized aeration disturbance (such as a typhoon). When the wind of a certain direction and intensity is blown over the sea for a period of time, because of the frictional force, the surface of the seawater will flow in the direction of the wind, and the flow of water molecules on the surface will drive the lower water molecules to follow the movement ( But the speed will gradually decrease), thus generating water flow. This is called "blowing flow."

2. Difference in seawater density. The salinity and temperature of the various parts of the ocean are not equal and constant. These differences will cause the density of the water mass to be different. The high density sea water is lighter and the low density sea water is lighter, so the sea water will flow. This phenomenon has become a "density tide".

3. Tidal rise and fall. Under the influence of the sun and the gravity of the moon, the seawater will periodically rise and fall. The water flow caused by the rise and fall of this water level is called the tide.

4. Compensation effect. Sea water is a fluid, and the fluid is continuous, so when the seawater somewhere flows to other places, the surrounding sea water will flow to make up for its lack, which causes the compensation flow.

So what is the black tide current?
The Kuroshio is a massive current that is part of the North Pacific Ocean Current System, because the surface waters near the equator are bombarded by the northeast trade wind (a member of the planetary wind system), plus the centrifugal force of the Earth's rotation (Coriolis Force), on the north side of the equator, forms a "Northern Equatorial Ocean Current" that flows from east to west. This ocean current was blocked when it came to the east coast of the Asian continent. Some of it turned into an equatorial countercurrent, and some turned to the north along the island of Taiwan and the Japanese island group. This part is the well-known Kuroshio.

After the Kuroshio arrived in northern Japan, it was blown to the east by the westerly wind (also a member of the planetary wind system), which was called the North Pacific Ocean Current. When the North Pacific Ocean current came to the west coast of the North American continent, it turned to the north and became the warm current of Alaska. The other side of the US West Bank flowed to the south and became the cool stream of California. This water flow will eventually return to the northern equatorial current.

The Kuroshio is from the equator, and its temperature is relatively high (the surface water temperature in summer is up to 30 ° C and the winter is not lower than 20 ° C.) It is therefore called "warm flow". It brings a warm, humid climate to the areas that flow through, as well as a large number of migratory fish (such as black mullet that appears in the eastern waters of Taiwan between spring and summer). During the flow process, the “fluctuation flow” caused by the terrain or due to the compensation will also bring the nutrients of the seabed to the upper waters, attracting a large amount of various organisms to gather, so that the fish can be enriched.

Second, the causes and effects of tides

Old experience fishermen often say that they want to see the "flowing water" when they go out. This water is the tide.
Everyone knows that the tide is caused by the gravity of the moon and the sun, but why is there a big tide and a small tide? Why do you have two rises and falls every day? What is the high tide?

1. The so-called "tidal". The ancients referred to the phenomenon of seawater fluctuations occurring during the day as "tidal", and the nighttimes were called "汐", which are collectively called tides.

2. The tides rise and fall. Seawater rises from a lower water level to a higher water level. This process is called a high tide, and the low water level starts from a higher water level. This process is a low tide. When the water level rises to the highest point, it is called full fry or climax, and when it drops to the lowest point, it is called dry or low tide. In addition, when the water level reaches the full or dry tide point, there is usually no time for the sea surface to rise and fall. This is called mooring or flat tide.

3. The level of the tide level. In different places in the same tidal water, the level of water level is not the same, and the level of tidal water changes in the same place on different days.
The difference in water levels on different days is mainly caused by the relative positions of the moon, the sun and the earth. The new moon or the full moon, the moon, the sun, and the earth are roughly arranged in a straight line. At this time, the moon and the sun are on the side of the earth or on opposite sides. Due to the gravitational effect, the phenomenon that the temperature difference between the full and the dry tides is the largest. This is called "the tide". (But it will actually be delayed for two or three days). When you look at the top or the second quarter, the moon, the sun, and the earth are roughly arranged in a right triangle. At this time, the gap between the full and dry tides is the smallest, that is, "small tide."
As for the gap between the Manchu Dynasty and the dry tide level, it is called the tidal range. The fullness of the same place also changes periodically. It will change from small to large, and then from large to small. The distance between the highest tide level and the lowest tide level is called the intertidal zone.

4. The cycle of tides. The time when the tides are full is different every day; the interval between two full or two dry tides in the same place is about 12:25. In other words, the tide rises from the dry tide to the full moon, which takes about 6 hours. More (and vice versa), and the two-day tidal leave will be delayed by about 50 minutes, which is called the tidal delay rate.

5. The shape of the tide. There are two times a day, two tides, two tides, called a half-day tide; only once a day orgasm a low tide, called the full-day tide. If the actual tide in a region is not simply a half-day tide or a full-day tide, it is called a mixed tide.

When the full-day tide phenomenon is more obvious, the time from the full moon to the dry tide or from the dry tide to the full moon will be much longer than the 6 hours. This is commonly known as the "long tide."

6. How does the tide phenomenon affect fishing activities?
1 Although the tidal rise and fall is the vertical rise and fall of the sea surface, but under the influence of topography, sea breeze, earth rotation, gravity and other factors, it will cause the horizontal movement of sea water, in other words, it will cause the current, and the current is an important way of food handling. When the water flows during the mooring phase, the food will not be shipped to all parts of the country. Fish live in the ocean for a long time, and they are used to adjusting their work according to the water flow, so they often stop eating automatically during this time.
2 When the tides change, the direction of the currents often changes, which means that the place where the food is transported has also changed, so the fish will of course move.
3 The topography of the sea fishing area has changed greatly. Since the direction of the current has been changed, the punctuation is completely different. Therefore, if the angler does not have sufficient knowledge and mastery of the tide, the results will not be ideal.

Third, nearshore water flow

In addition to the Kuroshio currents and tidal phenomena, the state of seawater flow in coastal waters is also of great significance for fishing.
After the flowing seawater comes into contact with the land environment and the seabed, there will be many changes that have a major impact on fishing. These changes can be given the following names in the name of the fishing circle habit:

1, the flow. The so-called "current" is not a specific name for a certain kind of water, but a relatively powerful, fast, and most important stream in a region. Usually the direction is fixed (meaning that the direction is fixed during the high tide or during the ebb tide, but the direction may change after the tide is converted.) And the flow rate is significantly higher than other surrounding waters, it is called the current.
In this kind of running water, it is more difficult for the buoy fisherman to maintain the fixed position or the depth of the fishing shed. Some waters with particularly high water potential, that is, the long scales using dinosaur eggs or high load will also be taken away quickly. The situation is "flowing ditch". However, not all fishing grounds have a current. In some places, the dynamics of sea water are slow or disordered, and fishing friends will not define one of them as the current.
2, tributaries. This word "tributary" is not a proper noun, but a relatively small flow of water with a relatively slow flow direction relative to the current flow. Such water flows are pushed along the coast, and also rushed to the coast or out. The tributaries are not necessarily the branches of the current. Their formation is also affected by wind, waves, tides and other factors, and due to coastal terrain, The direction of the seabed changes its direction, speed, and scale.
3. Return zone. If the water flow in the movement encounters a change in the terrain (such as the inner bay, the bulge), or if the depth of the sea changes (such as a reef or a deep ditch), it is easy to form a swelled water mass in the water. This is the “return zone”. ". The scale of the recirculation zone will change with the flow of water. The more urgent the water flow, the wider the range of the recirculation zone and the more obvious the shape. The slower the water flow, the less the reflow zone may be weak. The reflux belt is easy to let the food floating in the sea stay and rotate.
4. Anti-dial. A wave of waves rushing to the shore, with large and large seawater hitting the reef, and then turning over and pouring back into the sea, these waters must have a path to flow out, and the seawater flowing along this path is called "reverse tide" . The direction is from the shore to the outer sea, and the organic matter on the shore can be washed into the sea and taken out, so it has the strong charm of attracting coastal fish. The method of finding the counter-dial is very simple. Just pay attention to the white foam caused by the broken waves. If the white foam forms a white foam that drags out a considerable distance continuously, that is it!
5, the tide. The so-called "trends" are two (or more than two) streams of different directions or flow rates that are interlaced, impacted, and rubbed together, thus creating a water area with a smooth surface, no seemingly little flow, and a stagnation of debris. This kind of water area is like a crossroad in the ocean. It is the place where fish and food meet and gather, so it is often the punctuation of the squat.

There are two main factors that affect the fishing activities in the coastal waters. One is the curved bump of the coastline, and the other is the change in the depth of the water.
(1) Coastline. Monotonous and straight coastline, often lack of changes in the underwater environment (the beach is a typical example), and the water flow direction of this type of water is mostly parallel to the coast, the flow rate is stable, no food gathers here, so the fish will not concentrate. it's here. The environment with obvious zigzag and unevenness is very rich in water flow, waves, etc. It is easy to form conditions for attracting fish, such as returning belts, counter-tricks, tides, etc., so the possibility of fishing and fishing is obviously higher than that of monotonous straightness.
(2) Depth changes. The depth of the sea is not only related to the ability of fish to adapt to water pressure, but also has a significant impact on seawater temperature, water color, salinity, transparency, water flow direction, speed, etc., so it also affects the way fish live and move. .
For example, a rock surface with a flat surface and lack of undulations, whether it is gentle or steep, or even extended to the water as a fault, is not easy to attract fish. However, if there is a depression, a valley or a bulge in the flat bottom field, then the base of the groove and the bulge will become a place where the active fish in the bottom like to inhabit, and the uplifted terrain is easy to cause the current to rise and deepen. The food at the place is brought to the shallows, so it is often the place where the surface active fish gather.

For fishing, the relationship between the marine substrate and the life of the fish is important in two aspects, namely, habitat and reproductive behavior.
(1) Habitats. Some fish do not come into contact with the seabed for the rest of their lives because their food is also in the upper layers of the ocean. These fish are often referred to as foreign or superficial migratory fish. However, most of the targets of the fishing do not belong to these fish, but to the species that are close to the sea floor or even live directly on the seabed. Some of these species are simply squatting on the bottom of the sea, such as oysters (flatfish), oysters (devil fish); others prefer to hide in the gaps, such as groupers, sea otters, etc.; In the evening, find a cave to sleep, such as the parrot fish, most of them belong to this. However, more fish species are used as habitats in such a changing environment. When they are safe, they rush out to enjoy the abundant food nearby. When they are in danger, they quickly enter the barrier to escape.
However, in each of the above fish, there is a difference in the choice of environment (substrate) for each type of fish. For example, black carp prefers to live in a reef-sand mixed zone, Jiayu prefers gravel topography, and black hair tends to accumulate in a purely reef area. .
(2) Reproductive behavior. Most fish are oviparous, but there are also viviparous births or births between the oviparous and the viviparous. Regardless of which type of reproduction they are, choose an environment suitable for reproduction. In a broad sense, it is necessary to consider the nutrient supply before mating, the environment required for the growth of eggs or larvae, and the physical recovery of broodstock after breeding.
Fish eggs have differences in their floating, sedimentation and adhesion. Floating eggs require a proper flow of water to bring the eggs, and float to the appropriate juveniles to grow gold and eat. Settlement eggs need to have enough small gaps on the seabed (such as gravel topography) to let them settle, and the feet must be stable and smooth, otherwise the eggs will be washed away or corrupted, and the sticky eggs need to be stable and stable. The water flow is smooth and there must be enough concealment, otherwise the eggs will soon be eaten by other fish!
As for the tonic before and after mating, it goes without saying that it is directly related to food abundance, and a large part of the food source of the target fish species is directly attached to the substrate, such as algae, crustaceans, shellfish, etc. Therefore, the impact of the substrate is very significant.
Attempt on the wind
The East Asia-Pacific region is a region with changing weather. From the perspective of Taiwan, the following cyclical changes will occur in general: after about three months, the direct solar position extends from the equator to the north, which promotes the Siberian cold high-pressure intensity on the northern continent. Weakened, the Pacific high pressure is gradually developed, so the northeast monsoon strength is gradually receding, the southwest wind began to replace it; in May and June, the ocean and the mainland air mass pushed each other, forming a stagnant front near Taiwan, causing the so-called rainy season; July and August The strength of the inter-Pacific high pressure has reached its peak. The southwestern and southerly winds of Taiwan are the mainstays. However, during this period, the ocean is prone to tropical depression due to the evaporation of large amounts of water vapor. When the low-pressure intensity reaches a certain level, a typhoon is formed. Therefore, after the seventh, eighth, ninth, and tenth months, the sun moved directly to the south, crossing the equator and entering the southern hemisphere, causing the Pacific high pressure to gradually weaken the east retreat, and the cold and high pressure in the northern continent regained its advantage, causing the northeast monsoon to begin to go south, and The weather in this area is dominated from February to February.
According to the above rules, the wind or weather systems affecting the East Asia-Pacific region are mainly the following:
(1) Northeast monsoon. Basically from the Siberian continent, low temperature and dry, the form of water vapor and ice crystals exist in the sky, but when it moves eastward, it will be warmed up, and the water vapor will be absorbed along the road, so the weather will become haze and wind. Big, light rain, and a strong cold front on its front edge.
(2) Meiyu front. The Meiyu front formed by the mutual cooling of the Pacific heating group fish continental air masses often causes obvious wind changes and rainfall due to severe disturbances and a large amount of water vapor. When the Pacific high pressure is strong, the detention front will be moved to the northwest, and the Taiwan area will be covered by oceanic air masses, and the weather will be sunny and hot. If the mainland's cold and high-pressure forces are strong, the stalled front will move to the southeast, and the weather in Taiwan will become cloudy and rainy.
(3) Typhoon. Needless to say, the dangers of typhoons, but it has three neglected side effects that must be mentioned, that is, southwest air, long waves and violent tides.
The southwesterly airflow is different from the southwest monsoon. The monsoon refers to the wind that continues to blow for a long time and a large range. The airflow is a climatic phenomenon that is end to and varies greatly. After the typhoon passes through the Taiwan area, it will introduce a strong southwesterly airflow due to its counterclockwise rotation. This airflow from the South China Sea is accompanied by a large amount of water vapor, which often causes serious disasters.
The long wave is a very frequent wave. It is often caused by the strong wind and low pressure of the typhoon. It can travel far away, and the speed of propulsion is much faster than the speed of the typhoon itself. Therefore, it has a safety for the fisherman. Great threat.
The storm is another big trouble caused by the typhoon. Its cause is similar to that mentioned in the previous paragraph. Because the air pressure in the center of the typhoon is very low, the seawater will be sucked up to raise the sea surface, and the strong wind will blow up, and the seawater will be more accumulated due to the accumulation. At this time, if the tide rises again, it will cause a seawater intrusion disaster in the coastal areas.

(4) Southwest monsoon. In the east coast of the Asian continent and the western waters of the Pacific Ocean, if there is no typhoon or tropical low pressure in summer, it is usually sunny and hot, and the southwest wind is weak. The influence of this monsoon is not obvious, but because the sun continues to add to the surface and lacks wind regulation, a strong updraft near the surface of the earth often develops into a tall, thousands or even tens of meters, with an anvil at the top. a huge cloud column, such a cumulonimbus cloud with a large amount of water vapor, which is cooled by high altitude, will form a rapid and heavy rainstorm, and this rainfall can cause strong earthquakes because it is washed down with cold air. The wind has changed, forming a gust of wind reaching the level of eight or nine.
Common sense about the waves
The waves are the turbulence that occurs when the seawater is subjected to external forces. The most obvious and common cause is the wind. But there are a lot of external forces that can also cause waves, such as changes in the earth's crust, volcanic eruptions on the seabed, and tides.
Although the waves will spread outward from the place where they occur, the water molecules are not removed as the waves pass. They only move up and down in the original place. Another special phenomenon of waves is that the depth of their influence is about half of its wavelength, that is, if a wave with a distance between the peak and the peak of 10 meters occurs somewhere, then in the depth of more than 5 meters, it feels Not less than its dynamics.
In the above brief description of the general nature of the wave, fishing friends still remember the "long wave" mentioned in the previous section? The so-called long wave is a wave from a distant sea that has been separated from its source of origin (for example, caused by a distant typhoon). The wavelength of this wave is very long, the shape looks smooth and gentle, and the wave is not high. Therefore, people often ignore its danger or it is not easy to detect its arrival, but its energy is extremely impressive and it does not decay much during the journey. So it can affect far away places.
When such long waves propel up near the land, as the depth of the sea becomes shallower, the kinetic energy accumulated in the waves begins to transform into potential energy, which shortens the wavelength and increases the amplitude, which means that the seawater appears “upwardly stacked”; the water depth changes. The shallower, the higher the stacking height, and because of the hysteresis of the seabed friction, the wave transmission speed in the deep is slower than the surface, so the wave shape also becomes forward leaning, and finally the wave peak can no longer maintain a steady state and collapse. A lot of sea water suddenly slammed into the shore.
 This phenomenon occurs if it occurs on a steep, deep rocky coast or at the front of a breakwater. Because the depth is rapidly shallower in a short distance, the peaks of the peaks may overlap to a level beyond the foothold of the people. The release of kinetic energy and potential energy, a brain loaded with fishermen who can't avoid it, so the fisherman's fall into the sea happened!
Wind speed and wave height correspondence table

In the sand-sand zone where the depth change is moderate, the long-wave effect will not be very serious. However, if the incoming wave is triggered by a strong seabed earthquake, it may cause a tsunami like South Asia on December 26, 2004. s damage!
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