Distribution Characteristics of Bottom Litter in Chinhae Bay, Korea

A study on the amount, distribution and item of bottom litter on the sea-bed was conducted by the bottom trawl net at 5 sections in Chinhae Bay over a year. The number and weight of litter found per unit of swept area (1 hectare) in each section were estimated as the range of 8.76-80.63 pieces, 3.51-108.39kg, respectively. The seasonal variation of high (Aug., '97) and low season (Feb., '98) in quantity was small, and it was about 2 times as the range of 24.58- 52.61 pieces/ha between them. But the weight variation between high (Apr., '98) and low season (Aug., '97) was very large, about 30 times as the range of 4.06-119.64kg/ha. The largest and second composition on the weight of bottom litter in Chinhae Bay are $76\%$ in other-litter with compound and bulky materials, and $93\%$ in fishing gear, respectively. The relationship between quantity and weight of bottom litter was not occurred due to the variety of specific gravity. Of the fishing gear, fishing nets was portioned to be 2.571kg/ha in weight and $84.9\%$ in composition. So these results prove that fishing nets were discarded as the most part of fishing gear during fishing activity in the bay. The largest composition of the soiled state classified into 3 styles in overall bottom litter was $69\%$ in very soiled state, and the second one of $28\%$ in the soiled state. On the other hand, new state is very small and portioned in $3.0\%$ of all. Chinhae Bay was estimated to be about 10 times in quantity and about 36 times in weight of Tokyo Bay. Therefore, these suggest that Chinhae Bay is a very serious polluted estuary caused by the bottom litter such as heavy and bulky wastes, fishing gear.