The problems encountered by fish populations living in Lake Van basin and their possible solutions.

This study was carried out to determine the problems effecting the fish populations in Lake Van Basin and to discuss some solutions for mitigation. Sand pits on the stream beds were determined as the biggest problem because they destroyed the bed structure and made the water turbid. The works of these sand pits had negative effects during the spawning migration of fish such as Chlacalburnus tarichi, Capoeta capoeta and Barbus plebejus ercisianus. In this period, the turbidity and the destruction of stream bed not only can affect negatively the brood stock but also caused mass destruction of eggs and larvae. During the spawning period in Lake Nazik, especially while Cyprinus carpio returned to spawning, it was observed that some suitable costal regions for spawning were encircled by trammel nets. Precipitation regime of Van Lake Basin was very variable. In some seasons (summer) aridness were observed whereas in some seasons (spring and autumn) floods were observed. Floods can very destructive to stream beds and banks; sometimes a large amount of original material can be carried away by erosion on stream bed and banks because of destruction of vegetation and misuse of the bed by sand pit works. Dam and regulators on the stream had been built without considering fish migration and there were no fish passes. It was determined that the biggest threatening problem on fish population were sand pits working on these streams that is prohibited by Fisheries act Nr. 1380. The sand pits works should be stopped or at least regulated. Regulator and the other constructions on the streams must be arranged to fish passes. This is essential for fish populations and sustainable fisheries.