Modifications of the fish fauna in the upper Tisa river and its Southern and Eastern tributaries
In the upper Tisa and its main tributaries on the left shore: Vi§eu, Iza, Sapanta, Some§, Barcau, Cri§ul Repcde, Cri§ul Alb, Cri$ul Ncgru and Mure§, there were identified a number of 64 fish species and one of lamprey, Eudontomyzon danfordi. A number of 54 fish are native species, including an addit...
|Series:||Tiscia monograph series
Ecological aspects of the Tisa River Basin : 10 years anniversary regional conference 21nd - 24th March 2002., Târgu Mureş, Romania
|Kulcsszavak:||Tisza - élővilág, Halak - Tisza|
|Summary:||In the upper Tisa and its main tributaries on the left shore: Vi§eu, Iza, Sapanta, Some§, Barcau, Cri§ul Repcde, Cri§ul Alb, Cri$ul Ncgru and Mure§, there were identified a number of 64 fish species and one of lamprey, Eudontomyzon danfordi. A number of 54 fish are native species, including an additional endemic species (Scardinius racovitzai), and 11 fish species are allochtonous. Some of them have been rccolonised in some of the rivers where they were formerly abundant. In the case of many of these species, the data represent the last results of our field research carricd out along the rivers (during 1992-2001), pointing out that considerable changes of the ichthyofauna occured. In the last dccades we attend to the alarming numerical decrease of the number of fish species, or the range and numerical modifications of fish from some rivers' sections. For the present day a number of 17 native species are undergoing a numerical regression or have become almost extinct, and 8 fish species have been favoured by the modification of the aquatic biotopes. The natural life conditions changed in the river bed, modifying the fish communities, especially in those located downstream to the towns. According to the ccological requirements of the fish species and their adaptive resources, we propose a number of four fish categories, living in many of the studied rivers. The presence of these fish categories along the affected strctchcs of the rivers represents a measure for the fish fauna changes.|