Abundance of striped venus (Chamelea gallina L., 1758) stocks in different regions (Sinop-Kastamonu) with seasonal growth, and socio-economic analysis of fishing boats

Striped venus has an important role in the Turkish fisheries. In this study, it was aimed to determine the stock size, the demographic distribution, the length composition and the basic population parameters of striped venus in the Black Sea. In addition, investigation of the socio-economic situation of the fishermen who benefit from this resource was also targeted. The samples were taken by hydraulic and mechanic dredges and results were calculated by using swept area method. The research area was divided into five sub-areas. The size of stocks in the sub-areas were determined as 11,723.58±5,167.262 tons in Cide, 35,082.943±27,510.947 tons in İnebolu, 10,077.05±4,970.683 tons in Türkeli, 3,304.361±3,215.101 tons in Ayancık and 1,431.296±1,703.504 tons in Sarıkum in 2011. They were also specified as 13,820.408±6,977.857 tons, 3,4841.937±14,623.708 tons, 8,148.269±5,006.737 tons, 3,420.716±3,093.67 tons and 2,023.743±2,832.63 tons, respectively, in 2012. Von Bertalanffy Growth Parameters were calculated as Lt=32.28[1-e–0.249(t+0.262)] and Wt=9.74[1-e–0.249(t+0.262)]2.9072. Length-weight relationship of C. gallina was W=0.0004L2.9011 in 2011 and W=0.0004L2.9072 in 2012. The results showed that C. gallina had a negative allometric growth. The socio-economic evaluation of 27 vessel owners revealed that all of them had a family from fisheries background and they had an average professional experience of 24.29 years. The average gross production value of the vessels was found as 220.861 TL/boat/year. The average net profit of the vessel owners was calculated as 77.595,5 TL/vessel/year and the average gross profit was 104,953 TL/vessel/year. It was found that Return on Investment (ROI) was 21.02%, financial profitability was 21.35% and the turnover rate of the investment was 59.84%. The vessel size and engine power were not effective on the income of the vessel owners (p>0.05). Positive correlation was observed between the number of the days in the sea and fisheries income (p>0.05). The results of the study indicated that two years of fallow period did not result in a big increase in the stock size. Environmental factors and predator effect have high impact on the increase of the stock size and the changes occurring in these conditions should be considered in the fisheries management. Some vessels could make loss in the absence of tax free fuel subsidies independent from the total catch amount of the fishing fleet. An increase in the number of fishing vessels would decrease the average income per vessel. This situation could increase the pressure on the resources. For this reason, the number of vessels should be limited with 30-35 vessels not to increase the pressure on the resources as well as not to decrease the average income per vessel.