Vetenskapen till hjälp för sportfiskaren

Experienced anglers have their own secrets for finding promising fishing spots. These secrets are obtained through years of experience, trial and error. To help fishermen can come to ichthyology – a section of science that studies fish.

Let’s start with lakes. Depending on the type of lake, the species composition of fish and their habitat can vary greatly.

What types are lakes categorized into?

Scientists who work with freshwater aquatoriums, divide them according to several main features.

• By shape;
• by depth;
• by flow;
• condition;
• how they’re positioned in the landscape;
• how they are used;
• salt content;
• trophicity;
• and, finally, by origin.

How are fish distribution in aquatic areas studied?

To get the most complete picture of how and where the inhabitants of a water body live, ichthyologists use trawl surveys. A navigator with an echo sounder option records the entire trawling process. To get the most complete information about what lives in a water body, it is necessary to conduct about thirty trawl surveys. This is a very labor-intensive and expensive process, so not all water bodies can get an informative picture. In the middle zone, the main object of study is the most common fish species. Among them: perch, roach, bream, pikeperch.

According to monitoring, non-predatory fish practically do not change their “residence”. Predators are more mobile: if this year they can live, for example, in the northern part of the reservoir, next year – in the south-western part. The reason for such behavior may be fishing pressure.

In which lakes do fish like to settle?

In terms of species diversity of fauna, scientists also distinguish several types of water areas. First, these are those lakes that are loved by tench and pike. In such water areas, the bottom is flat, and most of the surface is overgrown. In these water bodies there are a lot of fish, while they are prone to swamping. The second group is bream lakes. In such water areas, there are many floating and water-air plants on the shore. There are also deposits of silt.

Sudak most of all likes large water areas with abundantly overgrown banks, but with little underwater vegetation. The bottom of such reservoirs – with silt deposits, which alternate with sandy-stony shoals.

Deep and large water bodies with steep stony shores with poorly developed vegetation are favored by whitefish. In these water areas, the water is clear and cool, which even in winter is rich in oxygen. But other fish species do not like such water areas.

Despite this classification, there are still common features that are characteristic of the fish habitat. The first such point: the less in the place of human impact – the more fish there are. Young and small fish prefer the coastal zone. If there are cold keys in the water area, then there will be large predators near them. If the plants in the water are distributed by islands, then the fish will hide exactly in such places.

How do river inhabitants distribute their “place of residence”?

Ichthyologists distinguish several categories of how fish are distributed in the water area. Uniform type in nature is quite rare. Each individual is equally removed from neighboring ones. With this distribution, food competition between fish is minimal. With the diffuse type, they live unevenly, in a random order. They are removed from each other at unequal distances. This is explained by the fact that their habitat is heterogeneous. It is this type is most often found in natural reservoirs. Mosaic type is most often found in small rivers in the North. Groups of individuals are formed, between which large unpopulated spaces can be observed. This may be due both to the fact that the environment is contrasting and to “social” factors that force fish to form groups.

To give an example: a typical small northern river is home to ten to twenty species of fish. When the temperature rises from 8 to 12 degrees, there is an active growth of aquatic inhabitants. After spawning, some fish die, some – migrate. The density of the “population” falls, along with it, the chances of success for the fisherman are reduced. Following the active reproduction of insects, the number of fish increases again, and fry settle in the places they like. In the fall, when the water temperature drops, the density decreases again.

How to find a promising place on the river?

In rivers, scientists distinguish several types of biotopes – places with similar conditions, where certain representatives of fauna live.

• Thresholds. They are characterized by a depth of 20 to 40 cm, flow velocity from 0.7 to 1.2 m / s. On the bottom there is a mixture of boulders and pebbles.
• Rolls. Depth can be from 10 to 20 cm, current velocity – 0.4-0.6 m/s. The bottom is usually covered with pebbles and small boulders.
• Shoulders are characterized by a depth of 40 to 70 cm. Current velocity does not exceed 0.3 m/s. The ground is sandy or covered with silt.
• Areas with holes, the depth of which can be up to one meter, are called bochazhki. The ground, as well as the current velocity, is most often the same as on the shoulders.

Depending on the season, fish can change their favorite places. Of course, river inhabitants are also affected by many other factors: wind, temperature, pressure, precipitation.

Summarizing, it should be noted that “residence at the place of residence” can be very different for fish of different species. Some like to “move” depending on the season or under the influence of other factors. In any case, the distribution of inhabitants depends primarily on their needs for food, so the angler must imagine what his potential trophy eats and how he is looking for sustenance. Theoretical knowledge of the fishing spot will help to get the dream catch.