Browsing by Author "Cetinkaya, Osman"

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The Problems Encountered by Fish Populations Living in Lake Van Basin and Their Possible Solutions
(Ege Univ, 2006) Elp, Mahmut; Sen, Fazil; Cetinkaya, Osman
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.
Some Biological Properties of Carp (Cyprinus Carpio L., 1758) Living in Kockopru Dam Lake, Van-Turkey
(Medwell online, 2008) Elp, Mahmut; Sen, Fazil; Cetinkaya, Osman
This study was carried out to determine some biological parameters of carp populations introduced to the Kockopru Dam Lake on the Zilan River in Lake Van Basin and conducted between December 1999 and August 2001. Sampling was carried out monthly using hand nets and trammel nets. It was determined that carp become a sustainable population and is caught by fishermen. The maximum age was determined as VII; fork length as 61.7 cm and weight as 6002.6 g. Length-weight relationship was estimated as log W = -1.402+2.847 log L and age-length relationship was determined as Lt = 84.070 (1-e(-0.126(1+0.801))). It was also determined that male female ratio was 1:0.94 and maturity size was determined as more than 45 cm for female. Reproduction period was observed in June. It was also observed that commercial fishing could be a big threat for the future of the Kockopru Dam Lake population because of undersized catch.