Fishing dredge in Jeollabuk-do began to become widespread in the 1960s and has continued to catch diverse kinds of shellfish in the productive fishing grounds around Dongjin River, Mangyeong River and Geum River estuaries. Since the 1970s, the construction of various large-scale industrial complex and the implementation of Saemangeum reclamation project have resulted in a decrease in main fishing areas and a sharp decline in shellfish production. As a result, dredge fishery has faced many difficulties. Dredge fishery in Jeollabuk-do is carried out with a total of 30 fishing permits as of 2016. Surf clams, hen clams, bladder moon snails, and common orient clams were mainly caught before the construction of Saemangeum dike while comb pen shells, purple whelks and ark shells are mainly caught afterwards. Inside the Saemangeum dike, most fish species have disappeared due to low water level and low salinity, and littleneck clams are caught using a jet pump type of fishing dredge. Outside the dike, the diversity of shellfish species has been reduced; comb pen shells are mainly caught. In this process, a lot of friction occurs due to the use of a reformatted dredge. Therefore, a lot of research needs to be conducted in the near future.

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.

Species composition and seasonal variation of aquatic organism in the marine ranchig ground of Taean, Korea were investigated using shrimp beam trawl from January to December 2010. A total of 99 species, 5,355,816ind./km2 and 84,697kg/km2 of aquatic organism were collected. Among them, fish include 9 orders 33 families 54 species, crustaceans include 2 orders 15 families 30 species, cephalopods consist of 3 orders 4 families 5 species, gastropods include 2 orders 3 families 4 species, echinoidea sp. include 1 order 2 families 2 species, bivalves were composed of 2 orders 2 families 2 species, and holothuroids include 1 family 1 order. According to the dominants by month, Palaemon gravieri was dominant in January, Cynoglossus joyneri was dominant in February, March, and June, and Hexagrammos otakii was dominant, in July. And Oratosquilla oratoria was dominant echinoidea sp. was dominant in April, May, and August and in September, October, November, and December. Cluster analysis based on species composition of the 38 most common species showed that the species were separated into 5 different groups. Group A was composed of species which were abundant in spring and summer, group B was composed of year-round residents, and group C was composed of species which were abundant in autumn.

Doam Bay is an estuary where harmful algal blooms (HABs) such as red tides develop frequently in summer. The bay also is influenced by freshwater inflow from Tamjin River in upper regions as well as from an artificial lake in lower regions. Phytoplankton size and species composition were investigated at six stations located in the lower regions in April, June and July, 2007. Physical properties (temperature, salinity and SS) were intensively measured for 3 days (5 occasions) after the freshwater discharges from the dike. The freshwater discharge affected temperature, salinity and turbidity in the study sites adjacent to the freshwater lake. Phytoplankton biomass was larger in April than June and it increased more in July. An explicit shift of species composition was observed. Diatoms were dominant in April and June (>70%) whereas their abundances greatly decreased and chlorophytes increased in July. Pseudo-nitzschia sp. was dominant at all stations (except St. 2) and this change was also detected in ecological indices such as diversity and dominance index.