Do Fish Lose Weight After Being Caught?

fishing boat

If you have ever wondered whether fish lose weight after being caught, then you are not alone. There have been several observations that some fish when caught could lose a few pounds. So, is that true and is it the same for all kinds of fish?

So, stay glued to this article as we seek to answer these questions. We will explore whether fish lose weight after they are caught.

Do Fish Lose Weight After Being Caught?

A fisherman that catches a fish might be surprised to see that the fish looks like it has shed off some of its weight after it has been caught. What happens is that fish tend to expel some of their contents when it is caught.

So, a fish will release things like water and gas, then, shed mucus and scales could also be released. This could result in the fish losing about 15% of its weight when it is caught. This process usually occurs after thirty minutes of when the fish was caught.

This means that if you plan on weighing the fish that you caught or you are simply a conversationist, then the best practice will be to weigh the fish immediately after you catch it. If you wait for an hour before weighing it, the fish most probably has lost some of its weight.

What Causes Weight Loss In Fish After It Is Caught?

The exact amount of weight that a fish will lose depends on a few factors. These factors will include the species of the fish in question, the conditions surrounding its catch, and whether or not you cleaned or gutted the fish before weighing it.

In general, though, a fish will lose close to half of its weight when it is caught and taken out of water. This is because water makes up the major part of a fish’s weight. In some fishes, water could make up for 90% of the fish’s weight.

Most fish could even get dehydrated after they are taken out of water. This effect of barotrauma on fishes can vary with different species. While some fish could withstand the effect of barotrauma, some species can’t be that resilient. This can cause some digestive problems in fish.

Barotrauma is used to describe the number of injuries, or trauma, a fish can experience when there are changes in atmospheric pressures. When fish are caught by anglers, these rapid pressure changes occur when fish are taken to the surface of the water from deep water.

The resilience of a fish to barotrauma depends on different factors. This could be down to the swim bladder volume and the amount of gas inside. The swim bladder is the major determinant of barotrauma in fish which can ultimately lead to weight loss in a fish.

This, therefore, means that a detailed knowledge of the state of the fish swim bladder before it is decompressed will help you understand the barotrauma effect. As the swim bladder has gas in it, the volume of the swim bladder will be relative to the pressure.

Different species of fish have different responses to this barotrauma effect. While the rockfish could display some effects that can be influenced by depth, others might not. This is why swim bladder morphology and foraging behaviour of rockfish will vary from specie to specie.

American eels have a good resilience towards barotrauma effects. During its silver phase transition, this fish will show some physiological changes. These changes have been believed to foster their high barotrauma resilience.

Resilience to barotrauma in fish varies and there is no established relationship between barotrauma and survival. There could be some internal and external changes in fish due to this barotrauma effect.

Internal changes due to barotrauma include haemorrhage, swim bladder tear, and organ torsion. The external changes that could occur include corneal gas bubbles, exophthalmia, and abdominal eversion. Generally, these changes could affect the conservation and exploitation of fish.

As we have said earlier, fish can lose weight in several ways after they have been caught. Blood loss, regurgitation, defecation, and barotrauma are among the possibilities. However, water loss stands as the most compelling factor in this weight loss.

Since fish live in water, they regularly find a way of maintaining the right balance of water in their bodies. They do this through a process of osmoregulation. This will invariably mean that the fish will constantly have to excrete excess water as they pump ions into their blood in freshwater.

When the fish is stressed and kept in freshwater, however, they will stop excreting water and start gaining weight through osmosis. This natural flow of water will continue even if the fish dies and they are still held in freshwater.

It could be difficult to keep large fish alive after it is caught and so, considerably you might not be able to control the weight loss. Hardy species like catfish can however be held alive for a while before you release them again.

For tournament purposes, most anglers are concerned with the weight of fish and so they want to ensure that fish stay alive for as long as possible. However, because they might not have the equipment to keep large fish alive for long, they seek out other solutions to do this. Keeping a fish alive could help preserve its weight. When it is dead, it could weigh lesser than when it was caught.

Related FAQs: Do Fish Lose Colour When They Sleep?

How Do You Keep The Weight Of a Fish Intact After It Is Caught?

If a fish cannot be kept alive, then you have to ensure that they are damp and cold so that you can keep them from dehydration and prevent the quality of meat. This means that you could work with keeping the fish in a cooler filled with ice. The best practice will be to use one pound of crushed ice per pound of fish so you can keep the cooler as chilled as possible and avoid brushing.

A study was conducted on dressed chinook salmon that was held in a chilled environment for four days. It was found that the fish not only maintained its weight but gained an extra 5%. The issue with water gains however is that it can impact the quality of meat.

So, when you keep fish in a slurry of ice and water, it should help the fish keep its weight on and possibly result in weight gain. You could also work with wrapping the fish in a plastic bag before keeping it in the cooler. This will help the fish not touch the water as compartmental equalization could leach off some of the fish’s moisture if there is a discrepancy between the fish and the water.

You have to ensure that you don’t damage the gills of the fish too. When larger fish lose blood, it could cause them to lose weight. Another thing you want to make sure of is that the cooler should be big enough for the fish. This will help you tilt the head of the fish upwards. If they are angled downward, it could cause weight loss.

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A fish can lose weight after it has been caught. Water is responsible for a bulk of fish’s weight and so taking them out of water could cause a significant decrease in their weight. We have been able to consider some other factors that could make a fish lose weight.

So, read through, enjoy our insights and stay informed.

Written by Justin Michaels

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