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Migrations

03.10.2017

Migrations of fishes usually are explained by difference in amount of food between sea and river habitats. In the river taimen generally moved down in the spring, up in the summer and down in the fall, fishes aspire towards cold water.

 The history of migrations was studied by method of definition of a ratio of Sr/Ca (strontium/calcium) in the otoliths of adult fishes. To keep individuals in a live look, the distinctive sign of anadromous fishes from river – guanin pigmentation of scales at the basis of a tail fin is offered.

 Spawning and in the south of Sakhalin takes place in the rivers of Hokkaido at the end of April - the beginning of May, in the north – from May 20 to June 5. The repeated slope of fishes after spawning usually happens in July, and from August to November they come into fresh water again. After a slope both juveniles, and  individuals keep near mouths of the rivers or in lakes and estuaries. The taimen doesn't make extended sea migrations what numerous calling fresh water during a summer feeding testify to.

 In the large rivers the juveniles of a taimen are acquired up to 5-7 years, reaching length of 40-50 cm. The limitation of places of feeding in the small rivers promotes a juveniles slope at earlier age (2-4 years) and at the smaller sizes (10-25 cm).

 At the end of September - the beginning of November the taimen comes back for wintering to lower reaches of the rivers or the lake. In lower reaches of the small rivers only small individuals winter.

 Unlike the Pacific salmons, communication of taimen through passage with sea waters not so strong, many fishes leave in lower sections of the rivers, to estuaries and sea gulfs, and the high sea don't reach. Moreover, an essential part of individuals from populations of the large rivers puts out not every year to sea and remains for all summer in fresh water. On duration and extent of migrations the Sakhalin taimen reminds not salmon, but loaches semi-anadromous more – charr or kundzha.

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