Fouling
Under Verbuttung refers to the disproportionate increase in the number of individuals of a fish population at strikingly dwarfism . Overall, the average size of the animals is decreasing and sexual maturity occurs earlier. Either a certain species can kill in a body of water, or this effect affects all whitefish species or all fish species without exception.
Species that are particularly susceptible to breeding are perch , ruff , bream , white bream , roach , tench and crucian carp , and sometimes also char. Flounder was also observed in some brackish rivers in the flounder (northern German: butt ).
Isolated small bodies of water into which no other populations can migrate are particularly at risk.
Burying is observed almost exclusively in managed waters and has anthropogenic causes. In natural waters without human intervention, the phenomenon of fouling is largely unknown.
Debris is particularly common in nutrient-rich lowland waters. The growth of most fish species is linked to the food supply in the youth stage. If the food supply and quality are insufficient due to strong competition for food within the own species, growth can end after reaching sexual maturity. Slowly growing fish species such as tench or perch are particularly affected. Despite their small stature, the fish reproduce and release a large number of juvenile fish that cannot be adequately decimated by the few predatory fish. The low predatory fish population, which has an unfavorable effect on the coarse fish population, is one of the main reasons for the breeding ground.
One consequence of the breeding is - due to the resulting lack of food - high intra-specific competition and the resulting short stature. This short stature is an adaptation to the location conditions and not genetically determined. If a broken fish is released in intact natural water, this process is reversible and the animal can grow to normal size.
The equilibrium between predatory and coarse fish populations in a shattered body of water can be restored after some time, provided that the large predatory fish are not caught unilaterally and specifically. Fishing (hegefishing) and stocking with large predatory fish can partially counteract the fouling.
literature
- Brassen - A special issue of the Blinker newspaper , No. 18, Jahr-Verlag, Hamburg, ISBN 3-86132-151-3 .
Web links
- NABU: Effects of angling in inland waters on underwater habitats.
- Filling as a consequence of intraspecific competition. ( Memento from June 27, 2012 in the Internet Archive )