The maximum sustained yield ( ) of shellfish caught through dredge fishery was 7,250 to 7,490 MT from 1990 to 1999, which was not affected by the construction of the Saemangeum Dike. The MSY from 2000 to 2016, under the influence of the dike, was 1,716 to 1,776 MT when the total annual fish catch was 1,000 MT or more, and 289 to 336 MT when it was less than 1,000 MT. The construction of the Saemangeum Dike led to a decrease in the catch volume of the offshore dredge fishery in Jeollabuk-do, to 4.2 to 23.7% of that before its construction. The allowable biological catch () was estimated to be 313 to 1,532 MT per year, which was about 72.3 to 94.3% less than before the construction of Saemangeum Dike. Currently, the dredge fishery in Jeollabuk-do relies on comb pen shells. For fishery management, the catch per vessel should be set at 51.0 MT/year or less, and the number of fishing vessels should be reduced to 22 as quickly as possible. Besides, in the long term, the number of current fishing vessels should be reduced to less than half in consideration of the comb pen shell collecting period in Jeollabuk-do.

Experimental fishing was carried out to compare and analyze catch characteristics of shrimp beam trawl in a fishing area and a non-fishing area during the period of fishing season and off-fishing season in the coastal waters of Geoje. A commercial fishing boat (4.99 tons) was used for the test fishing. The amount of total catches were 14,654g in the fishing area and 12,359g in the non-fishing area, shrimp catches of non-fishing area were much greater than that of the fishing area during the period of off-fishing season (June and August). However, total catches were 27,670g in the fishing area and 33,004g in the non-fishing area, shrimp catches of fishing area were bigger than that of non-fishing area during the period of fishing season (October and December). On the results of the study, catches characteristics between fishing area and non-fishing area showed the reversed results for the period of fishing season and off-fishing season.

The properties of sediment collected from seabed surface to 6cm depth on the four positions were analyzed to investigate turbulence of marine sediments by shrimp beam trawl. Types of sediments in the investigation area were (g)mS (slightly gravely muddy sand) and gmS (gravely muddy sand) showing high sand content, and (g)sM (slightly gravely sandy mud), gsM (gravely sandy mud) as well. It is estimated that position is more crucial factor than seasonal difference for the granularity variation of sediment in each investigation area. Finding the positional characteristics of sediment granularity was difficult before removing shells and organic matter. However, the average granularity is getting larger by going out from inland sea to open sea once those were removed. The granularity of marine sediment got narrow after processing in the fishing area for shrimp beam trawl but there was no big difference for granularity size before and after processing in the non-fishing area. This might be attributed to crushed shell particles going up and down again on the surface in the fishing area. To demonstrate the hypothesis mentioned above, the sediments driven by shrimp beam trawl need to be collected and analyzed.