gh GOBY HIBERNATES IN THE ICE

The lake where the fishers observed the hibernating Perccottus glenii is connected to the river by a narrow duct. This is about a meter-deep water body that freezes through to the bottom during the winter period in the Far East, the temperature dropping as low as 30-40 C below zero. All the fish that come over to the lake for the spring and summer spawning, in wintertime migrate to the river, but the Perccottus glenii stays. Till December the Perccottus glenii happens to be an occasional catch, but later they are no longer met as they hibernate. The Perccottus glenii hibernates in colonies comprising from several dozens up to several hundreds of fish of various sizes. If there is not much snow and the ice is transparent, than a bunch of Perccottus glenii can be clearly seen through the ice.

The winter habitat of the Perccottus glenii is a cavity in the ice. The cavity is made in the shape of hemisphere, the diameter varying from 20-30 centimeters up to 1.5-2 meters. The upper point of the cavity is 30-60 centimeters from the surface of the ice. Such hemispheres are frequently located above hummocks or water plant bunches. The hemispheres are filled with the air mixed with water and bits of ice - scientists call that the air/ice humid mass. The temperature in the Perccottus glenii' hibernation place is close to zero, so the fish remains torpid. Being pulled out of the cavity the fish moves slightly. When the Perccottus glenii get back into the water they quickly resume active movements. So far, Sokolov has failed to explain the origin of such cavities in the ice. Probably the Perccottus glenii build these cavities in the following way: the fish might bunch and excrete some substances from the slime, thus making the ice melt from below. Anyway, the more numerous the hibernating colony is, the bigger the hemisphere dimensions are and the closer to the surface the hemisphere is.

The Perccottus glenii's hibernation in the ice starts late in December and lasts till late April. The end of hibernation is a dangerous period. At the second half of April, when the lake is still covered with a thick layer of ice, but the water from melted snow is already flowing down from the banks, the abundance of magpies and crows gather on the lake, the birds swiftly catching the Perccottus glenii released from the ice. It is due to this row that the people disclosed the mystery of the Perccottus glenii's hibernation. However, judging by the fact that the Perccottus glenii are in excess in the lake and they are rather large, they easily bear the hibernation. The Perccottus glenii live even in the water bodies where the crucian carps do not stand the hibernation because of the severe wintertime conditions.

The scientists are not sure that the cavities in the ice is the only way the Perccottus glenii hibernate, although the fishers from the Amur river area believe that, having investigated quite a variety of water bodies.

The Antarctic seas where the water temperature falls below zero are also inhabited by fish species. Their cavernous liquids contain special substances - antifreezes, which simply excite the genetic engineers' and biotechnologists' imagination. It is difficult to study these substances as the fish possessing them inhabit extremely remote areas. Perhaps there will be no need to look for antifreezes in Antarctica. Apparently, the Perccottus glenii have an adaptation capability of the same kind similar to that of the Chukotka dallia blackfish, whose way of hibernation is still unclear. Anyway, both the Perccottus glenii and dallia can make an interesting subject of cryobiological experiments.

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