Why make a hole in the belly of the fish when the sea is released?

2021-01-11 | Weird Rokop Original |

First of all, this practice is real, and there is a certain scientific basis, almost the world has people doing this.

Just after entering the 21st century, with the development of science and technology, people began to track the survival rate of the fish that were released after being caught, and found that giving the fish a stomach to target the survival rate of some fish is indeed helpful, but it does not help some fish.Not much help.

Let me first talk about why it has a certain scientific basis!

Air pressure trauma of fish

We know that as the water depth increases, the pressure gradually increases, and the fish in the ocean live in layers. Each species lives in its own comfortable water depth. In other words, the water pressure for each species isdifferent.

When deep-sea fish are caught, they will suffer huge pressure trauma due to pressure changes, which is a bit like we cannot adapt to high altitude areas.

But the air pressure trauma of fish is much more serious than ours. The typical manifestations are swelling of the eyes, swelling of the belly, sometimes even the intestines protrude from the tail, the stomach protrudes from the mouth, etc.

The more serious fish scales will stand up, and even the fish body will rupture. When the gas is released, it will make a hissing sound like deflating a balloon.

As for why the fish reacts so fiercely, it is necessary to talk about an important organ of fish-the swim bladder!

How to inflate and deflate the swim bladder?

Mw bladder is the buoyancy control organ of fish. The buoyancy is adjusted by inflating or deflating the gas in the blood. This aeration and deflation of the swim bladder allows the fish with the swim bladder to move freely in each water layer.In order to make full use of the opportunity to eat, and those species without swim bladder such as many benthic species, most of the time can only stay near the seabed.

When the fish swim to the surface, the pressure of the water will decrease, and the gas in the swim bladder will expand. Under normal circumstances, the fish will usually reabsorb the expanded gas into the blood to adapt to changes in water pressure some fish alsoWill exhale from the mouth through a "hiccup" method.

However, when a hooked fish is quickly pulled to the surface, it will not be able to reabsorb or release the gas in the swim bladder fast enough, which is why some deep-sea fish expand so much when they come out of the water.

It is believed that fish caught from 10 meters of water will already be affected by air pressure damage to some extent, and pulling a fish from 20 meters of water to the surface will increase the gas volume of the fish bladderthree times.

In many cases, the expanded swim bladder will squeeze into the fish’s internal organs, which may cause irreversible or fatal injuries.

More importantly, such an "inflated" fish cannot swim from the surface to the depths of the ocean, and eventually it will become food for seabirds and other predators.

If you want to release a swollen fish, the only way is to exhaust it first to reduce buoyancy and allow it to swim to its own water layer.

This can let the fish slowly exhaust by themselves. Of course, there is also an artificial method that hurts. That is to put a needle in the fish's stomach and pierce the swim bladder to deflate.

This method is used by many people up to now, and the formal operation steps can be learned on the Internet, but exhaust is an invasive technique that may cause infection and damage other organs.

If you want to use this method, you must have some professional knowledge and a better understanding of marine fish, because the location of the swim bladder is different for different fish.

I also said earlier that giving fish to the fish has little effect on the survival rate of some fish, but why do many sea anglers believe that making a hole for the fish can indeed help the fish?

The survival rate of sea fishing release mainly depends on the depth

Alaska's research on Pacific cod showed that the swim bladder that broke during the decompression process will be sealed within 24 hours after being caught and resume normal function.

The recovery ability of wild marine animals is amazing. Those fish with small injuries do not seem to be fatal at all, and the swim bladder is indeed not a deadly organ if it is punctured. This may be the reason why the practice of "sticking the swim bladder" has always existed.one.

Now there are quite a lot of studies on the mortality of various fishes after release. In 2007, a study on the survival rate of sea bream after release from Western Australia showed that the survival rate of released sea breamMainly depends on the depth when it was caught.

This study involved about 700 sea bream samples at different depths. Among them, the death rate of sea bream less than 30 meters deep after release was very low 3.4%, and the mortality rate at 45 meters and 65 meters depth rose to very high 69%, the mortality rate of hook injury is low, and gas exhaust piercing the swim bladder with a hypodermic needle did not improve the survival rate of sea bream.

Digression: No specific data is given in the report on the death rate of hook wounds. The mortality rate of this one is very low. I am personally skeptical, because I saw in another report that fishing injuries affect the predation ability of sucking fish

Finally: How to release deep-sea fish?

Many people may be like me, thinking that slowly pulling the fish out of the water will allow them to adapt to changes in water pressure. That would be naive. This trick is useless.

In most cases, the pressure change is too severe, even if it rises slowly, the fish cannot adapt. In some tests, after the fish is brought to the surface from a height of 30 meters, it takes many days to adapt to the low pressure buoyancy.

The degree of air pressure trauma to a fish depends on many factors: including its depth, species, and the speed at which it recovers to a comfortable depth after release, etc., but it has nothing to do with how quickly it is pulled out of the water, neither do youIt may take a few days to pull it out.

Although slowly bringing the fish out of the water does not help much, it is helpful to release the fish into the sea quickly.

If you release quickly, the still swelling fish may swim deep enough to offset the effect of sudden decompression.

The picture shows: counterweight fish hook and counterweight box

Another option is to help the fish descend to a safe depth. This will use some tools, such as a counterweight box and a counterweight fish hook pictured above to let the fish and heavy objects go down together to ensure that the fish can reachComfortable depth, it breaks free on its own or we help open it.

If you don’t have any tools, you can only make a hole in the belly of the fish! An swollen fish will die if it is thrown into the sea, and there is a possibility of survival after a piercing.

Of course, it’s better to reduce deep-sea fishing. It’s best to reduce the damage to the ocean. It’s really hard to understand if you catch it and let it go!

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