Mortality Rates and Stock Assessment of Tench (Tinca tinca L., 1758) in Lake Yenicaga (Bolu- Turkey)

The mortality rates of the 291 tench sampled from the lake yenicaga between march 2009 and july 2010 were investigated, by the estimation of stock size, suitable fishing effort, yield and biomass determined to utilize most efficient way. total mortality (z), natural mortality (m), and fishing mortality (f) coefficients, stock exploitation (e) and survival (s) rateswere calculated as z= 0.55 year-1, m= 0.46 year-1, f= 0.09 year-1, e= 0.16 year-1, and s= 57.86%, respectively. during the research period 8344 (4350 kg) tench which were fished from lake of yenicaga, was calculated that in one fishing season 130204 (43317 kg) tench were found in the lake. to benefit from this stock most efficiently, by increasing the current fishing effort 203% were determined that 8793 kilos of yield could be obtained.