What Do Fish Eat in the Winter?
If you love ice fishing, you already know that there are plentiful fish to catch even in the heart of winter. However, the frozen conditions suggest that life shouldn’t be possible deep under the surface. When the water is so cold, it begs the question – how do fish eat and survive?
Some fish like trouts eat insect larvae and other fish in the winter, while some like cunners go dormant. Fish don’t feed as much in the winter since they slow their metabolism to adapt to colder temperatures and less oxygen. They also migrate to deeper bodies of water with more oxygen and food sources.
In this article, we’ll cover how fish adapt to the winter conditions and continue to survive. We’ll look at the ways they breathe, feed, and continue living, even in the coldest temperatures. So, let’s get started!
What Do Fish Usually Eat?
The diet of fish depends on the species and their habitat. However, generally fish eat some or all of the following foods:
- Aquatic plants like water lily and algae
- Decaying matter
- Other fish
However, food is readily more available in the warmer months than in winter.
How Do Fish Stay Alive in Winter?
When you look at a frozen lake, it’s hard to imagine that fish are alive underneath the surface. However, evolution has allowed fish to adapt to extreme conditions and continue living through the winter months.
Fish adapt to winter conditions in various ways:
- Moving to the bottom of the body of water
- Reducing activity levels
1) Water Temperature
A body of water like a lake is made of multiple layers. Each layer has a different water temperature.
During summer, water close to the surface is the warmest because it is heated by the sun. Colder water sits underneath this top layer, becoming progressively colder the closer that you get to the bottom.
As the season transitions into autumn/fall, the water has a more even temperature because of less sunlight. There is minimal difference in temperature between the top layer and the bottom of the lake.
Once the water has achieved a similar temperature, the process of fall mixing happens. Because there is minimal difference in water density, wind causes different layers to mix. This means that oxygen and nutrients from the top layer of the water are mixed into the bottom layers.
In winter, the top layer of water freezes solid into ice. The coldest water moves to the top and sits just underneath the ice. This means that the warmest water is actually found at the bottom of the lake.
This is where most fish stay during the winter so that they can survive. Some species of fish, like catfish, burrow into the top layer of sediment to keep their bodies warm.
2) Oxygen Needs
Fish also need oxygen to survive. There is no mixing of oxygen with the water under the surface during the winter, so oxygen reserves are limited.
Some plants continue to be active during the winter and generate more oxygen at the water’s bottom. However, when sunlight cannot penetrate the ice, they stop photosynthesizing and producing oxygen.
Fish are also more likely to die in winter in water bodies that have large populations of algae. When a large quantity of algae grows in one place, this is called an algal bloom. During winter, algae die and start to break down. During this process, the bacteria that decompose the algae are also consuming oxygen. This takes it out of the water and can be fatal for fish.
Fish are more likely to die from lack of oxygen in shallow bodies of water. In deeper lakes, the water holds a greater quantity of oxygen. Therefore, it is common for many fish to die in shallow water bodies.
3) Reduced Metabolic Processes
During winter, fish need to use as little energy as possible. Therefore, they go into a semi-hibernation state that allows them to conserve energy.
Their bodies undergo several processes, including:
- Slowing of heartbeat
- Reduced oxygen and food needs
- Decreased movement
When there is less oxygen, fish breathe less. They have lower metabolism rates in cold temperatures, so they need less oxygen and do less activity. Because fish are cold-blooded, they can enter a dormant state to conserve their energy in the winter months.
Fish need food to survive, but it isn’t the sole source of their survival. Therefore, by merely slowing their metabolic processes and moving less, their food needs are much lower.
Some species of fish migrate before winter to increase their chances of survival. A good example of this is trout.
Trout usually live in rivers and streams. However, these are dangerous environments in the winter because of the minimal oxygen levels and proximity to predators. In winter, they move to calmer waters like lakes or beaver ponds. This can be either downstream or upstream tributaries.
Some fish may stick together for group protection, while others may seek refuge around rocks.
Fish Don’t Feed As Much in the Winter
Fish do not need to eat as much during the winter because it takes longer for their bodies to digest the food. Therefore, different fish adapt to the conditions in varied ways.
1) Some Fish Continue to Feed
Trout often feed on drifting insects at the start of winter. This could include midges and mayflies. This is a great food source because it needs minimal effort. However, once the water freezes over, this is no longer a viable option.
When the lake is frozen, the diet of trout depends on its size. Smaller trout primarily eat insect larvae. Larger trout feed on smaller fish, which could include charr, longfin smelt, or perch depending on their habitat. Trout that seek shelter near rocks may also feed on crayfish or minnows.
Trout generally eat less during winter but consume enough to sustain them while their bodies are in a less active state.
The ongoing battle between predators and prey continues even in the heart of winter. Some fish, such as the burbot, are more active in winter. They have minimal competition because most other fish are in a dormant state, so they can hunt more effectively.
2) Some Fish Go Into a Dormant State
These fishes usually eat extra during the warmer months to increase their body mass. They often go into a dormant state during winter and eat very little or nothing at all. Their bodies use the fats, sugars, and even muscle tissues during the dormant state to sustain them.
For example, cunners are a fish that become dormant in winter. Cunners are ocean fish found in the North-Atlantic. Their bodies become inactive when the water temperature goes below 5℃ (41℉). Due to the lack of movement and activity, they do not need to eat during the frozen winter months.
In conclusion, all fish change during winter.
The majority of fish slow down their metabolic processes to adapt to the colder temperatures and reduced oxygen. This means that they eat less, if at all. They rely on the fat stores in their bodies, and their lower energy needs to tide them through the winter.
However, some fish continue to feed and even take advantage of the lack of usual competitors. They may feed the same or even more in winter as in summer.
In both cases, fish have adapted through evolution to adjust to winter environments. Therefore, there is always plenty of fish to be found when you’re ready to try out ice fishing.
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