The rarities caught by crabber Harri Bister are not going to be sold like other crabs.
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During this crabbing season, Harri Bister has caught a couple of dozen blue crabs. Reader’s photo
A crab farmer living next to Forssa in Tammela Harri Bister has caught a couple of dozen more or less blue-shelled crabs during the past crabbing season.
Bister says that he caught the crayfish from a small river in Tämla. In the river in question, there is a single section a few tens of meters long, where, according to Bister, there have been blue crabs for years.
Bister sells crabs, but says that the blue crabs are not going to be sold.
– They are such a beautiful color that I don’t want to sell them, he says.
For now, the crabs stay in Bister’s pool, where they are offered food and where the water is changed all the time. Bister has considered if you would inquire from the Maretarium, i.e. the public aquarium in Kotka, if there would be any interest in having crabs of a special color as inhabitants of the aquarium.
Bister says that two of the crabs were particularly blue. The blueness of the rest of the crabs caught varied. Reader’s photo
A few sub-strains of blue crabs
Crab biologist Although Jussila The University of Eastern Finland says that there are a few small subpopulations of blue crabs in Finland.
Iltalehti last told about a single blue shearwater found in Suomusjärvi at the beginning of July.
Jussila says that, based on Iltalehti’s previous story, she too has been contacted and told about the shareholding observations in Kuopio and Heinävedi. In these cases too, it has been a small stretch of river where blue-shelled crabs have been found.
According to Jussila, these are very local findings.
– When blue crabs reproduce with each other, the proportion of blue crabs increases, and they may completely take over a certain section of the river, says Jussila.
Jussila told Iltalehti in July that coming across a blue crab is extremely rare. He still stands by his words.
He says that for some reason blue crabs have now attracted an extraordinary amount of attention, and people are keen to report their sightings.
– Especially if it is emphasized that it is a rarer phenomenon, special cases come up in such contexts. For an individual crabber, encountering a blue crab is not necessarily rare, but everyday. However, you cannot generalize the overall picture through individual cases, says Jussila.
Blue crabs
According to crab biologist Japo Jussila, in the light of current knowledge, there are two different reasons for the crabs’ exceptional coloring. Coloring can also be caused by a combination of two reasons.
The first explanation is related to inheritance. Something may have happened in the crab’s genetics, which is why the crab does not produce all the pigments in its shell. The result can be a blue, green, red or even white crab.
Another possibility is that the mineral composition of clay-based water areas affects the color of the crab’s shell. In clay-based water areas, slightly more blue crabs have traditionally been found than in other areas.
Different traditional shades of brown serve as protective coloring for the crab. Crayfish with a more unusual color may fall prey to at least those beasts that prey based on color perception in addition to movement.
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