Whelk fishing (Rapana venosa Valenciennes., 1846) by using pots in The Middle Black Sea, juvenile culturing and determining some of their biological characteristics

This study, it is aimed to define whelk fishing by using pot, juvenile culturing in the lantern nets and in addition, to determine some of their biological characteristics and individual mussel consumption in cages between September 2007 and January 2008 in Sinop.3883 whelks were fished as a result of monthly sampling done in three different depths and with three different baits (mussel, mussel+fish, fish) and total catch amount was determined 178.9 kg. The average length of the fished whelks was found to be 64.9±0.23 mm and the average weight was found to be 46.1±0.51 g.When the amount of fished whelks in relation to depth of pots is considered, 2297 whelks at the depth of 15 m, 969 whelks at the depth of 25 m and 609 whelks at the depth of 35 m were fished. It has been confirmed that whelks are selective to the types of bait placed in the pots. 57 % of the whelks were fished by mussel baited, 37 % of them fished by mussel+fish baited, and 6 % of them fished by fish baited pots (P<0.05).40 whelks were fished for culturing experiment and were fed on mussels in lantern nets for a period of one year. The relative weight and length growth rates were calculated as 64.24 % and 294.85 % respectively. At the end of the experiment, the survival rate was found to be 85 % and length-weight relationship was found to be W = 0.0003L2.828 and r = 0.96.Totally 40 whelks were collected from the cages in an attempt to determine the threat which the whelks pose on mussels. The whelks were divided into eight different size classes and were fed on mussels for a period of thirty days. The total weight of 24.7 kg of mussels are consumed by whelks, mussels weight of the average daily consumption of each whelk was determined as 20.55±2.07 g. No relationship was determined between whelk length and mussel consumption (P>0.05). However, a strong relationship was found between the length of whelk and the length of the consumed mussel (r=0.66). The findings of the study have been presented and discussed in detail.Keywords: Whelk, Rapana venosa, pot fishing, lantern nets, growth, food consuption.