Jae-Bong Lee

Estimation of demersal fish biomass using hydroacoustic and catch data in the marine ranching area (MRA ) of Jeju

Hybrid surveys using hydroacoustic and fish sampling gears such as trammel net , trap were conducted toinvestigate total biomass , distribution and dominant fish species of the demersal fishes in the marineranching area (MRA ) of Jeju . Four surveys were carried out in June , August , October and November using38 kHz quantitative echo sounder . Catch data using trammel net and trap were used to calculate biomass andto examine dominant fish species . Fish schools were mainly detected in the waters of 20 meters below andaround Chagwido waters . By the result of fishing experiments , fish species living in MRA of Jeju wereabout 40 species , dominant fish species of a detectable fish such as Family Sparidae and FamilyMonacanthidae etc . were identified 59.4~68.8% of total biomass . Based on the hydroacoustic data , fishlength -weight function and target strength information , mean density of the demersal fish estimated were as

Sunxiuqinia dokdonensis sp. nov., Isolated from Deep Sub-Seafloor Sediment §

A novel facultatively anaerobic strain DH1T was isolated from deep sub-seafloor sediment at a depth of 900 m below the seafloor off Seo-do (the west part of Dokdo Island) in the East Sea of the Republic of Korea. The new strain was characterized using polyphasic approaches. The isolate was Gram-stain-negative, motile by gliding, non-spore-forming rods, oxidase-negative, and catalase-positive; and formed colonies of orange-red color. The NaCl range for growth was 0.5–7.0% (w/v) and no growth was observed in the absence of NaCl. The isolate grew optimally at 30°C, with 2% (w/v) NaCl and at pH 7. The cell-wall hydrolysates contained ribose as a major sugar. The DNA G+C content was 40.8 mol%. The closest related strains are Sunxiuqinia faeciviva JAM-BA0302T and Sunxiuqinia elliptica DQHS-4T (97.9 and 96.3% sequence similarity, respectively). The level of DNA-DNA relatedness between strain DH1T and S. faeciviva JAM-BA0302T was around 41% (but only 6% between DH1T and S. elliptica DQHS-4T). The major cellular fatty acids of the isolate were contained iso-C15:0 (25.9%), anteiso-C15:0 (16.7%), and summed feature 9 (comprising C16:0 3-OH and/or unknown fatty acid of dimethylacetal ECL 17.157; 13.2%). The predominant menaquinone was MK-7. On the basis of polyphasic evidence from this study, the isolate was considered to represent a novel species of the genus Sunxiuqinia, for which the name Sunxiuqinia dokdonensis sp. nov. is proposed; the type strain is DH1T (=KCTC 32503T =CGMCC 1.12676T =JCM 19380T).

Migration and distribution changes of the Sandfish, Arctoscopus japonicus in the East Sea

Distribution pattern and fishing conditions of sandfish, Arctoscopus japonicus in the East Sae were explored using catch and catch per unit effort (CPUE) by eastern sea Danish seine and coastal gill net fisheries from 2004 to 2008. A. japonicus was one of major target species for the eastern sea Danish seine and coastal gill net fisheries in the East Sea, which were caught from April to October for the eastern Danish seine, and from October to December for the coastal gill net, respectively. In recent, the distribution and centroid of fishing ground moved northward, as seawater temperature increased. The species spawned in the coastal areas of Gangwon, northern East Sea, during winter, started to move to deeper water after spawning from spring, extended widely from Gangwon to Ulsan, southern East Sea, during summer, and migrated back to the spawning ground off Gangwon during autumn.

Pseudoruegeria limi sp. nov. isolated from mud flats in the Yellow Sea in Korea.

A Gram-negative, aerobic, non-motile and rod-shaped bacterial strain, D-17T, was isolated from mud flats in the Yellow Sea in Korea. Phylogenetic trees based on the 16S rRNA gene sequence showed that strain D-17T belongs to the genus Pseudoruegeria and it shared 97.5xa0% similarity with the type strain of Pseudoruegeria haliotis WM67T. The sequence similarities with Pseudoruegeria litimaris HD-43T and Pseudoruegeria aquimaris SW-255T were 96.9 and 96.1xa0%, respectively. Strain D-17T was found to grow with 0.5–6xa0% (w/v) NaCl, at 20–30xa0°C, and at pH 6.5–8.0. Strain D-17T was determined to contain Q-10 as the predominant ubiquinone and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c, as defined by the MIDI system) as the major fatty acids. The major polar lipids were identified as phosphatidylglycerol, diphosphatidylglycerol, an unidentified aminolipid, an unidentified glycolipid, an unidentified lipid and four unidentified phospholipids. The DNA G+C content was determined to be 63.6xa0mol%. The DNA–DNA relatedness with P. haliotis WM67T was 32.5xa0%. The differential phenotypic properties revealed that strain D-17T can be separated from other Pseudoruegeria species. Based on the data presented in this study, strain D-17T represents a novel species, for which the name Pseudoruegeria limi sp. nov. is proposed. The type strain is D-17T (=KCTC 32460Txa0=JCM 19487T).

Lacinutrix chionocetis sp. nov., Isolated from Gut of a Red Snow Crab

A Gram-negative, aerobic, non-motile, rod-shaped bacterial strain, designated MAB-07T, was isolated from the gut of a red snow crab. The novel strain grew optimally at 20xa0°C, pH 7.0–8.0, and in the presence of 3% (w/v) NaCl. A phylogenetic analysis based on the 16S rRNA gene sequence indicated that the strain MAB-07T belongs to the type strains of species of the genus Lacinutrix. Strain MAB-07T exhibited 16S rRNA gene sequence similarity values of 95.5–97.8% with the type strains of species of the genus Lacinutrix. The predominant cellular fatty acids of strain MAB-07T were iso-C15:1 G (27.5%) and iso-C15:0 (21.7%). The major respiratory quinine was identified as MK-6. The polar lipids consisted of phosphatidylethanolamine, four unidentified aminolipids, and two unidentified lipids. The genomic DNA Gxa0+xa0C content was determined to be 33.3%, and its DNA–DNA relatedness values with the type strains of L. venerupis, L. mariniflava, L. jangbogonensis, L. algicola, and Olleya aquimaris were 28–32%. Based on the data from this polyphasic taxonomic study, strain MAB-07T is considered to represent a novel species of the genus Lacinutrix, for which the name L. chionocetis sp. nov. is proposed. The type strain is MAB-07T (=KCTC 42767Txa0=xa0JCM 30988T).

Long-term changes in the small yellow croaker, Larimichthys polyactis, population in the Yellow and East China Seas

The population of small yellow croaker, Larimichthys polyactis, in the Yellow and East China Seas has decreased significantly since the mid 1970s. Several management measures have been introduced to conserve it, but population size remains low. To rebuild this population, it is now necessary to consider more effective management methods based on the stock assessment. To determine long-term population changes, fishery and biological data collected over 34 years (1969-2002) were analysed. Yearly fish length compositions were analysed for the time periods 1968 through 1970, 1978 through 1982, and 1993 through 2002; and catch data was available from 1969 to 2002. Annual population sizes were calculated based on length composition, the relationship between total length and body weight, and total landings. Analyses showed that since the 1970s, average size of harvested fish decreased; the proportion of less mature fish (smaller than the 50% maturity length, 19cm) in catches has increased and the estimated biomass has decreased significantly. Consequently, the main management recommendation is that juvenile fish need to be better protected to allow the rebuilding of resources to a more sustainable population level. This will require fish size limit, permissible mesh size, and closed area and season regulations.

Larkinella roseus sp. nov., a species of the family Cytophagaceae isolated from beach soil

The taxonomic position of bacterial strain, designated 15J16-1T3AT, recovered from a soil sample was established using a polyphasic approach. Phylogenic analysis based on the 16S rRNA gene sequence showed that strain 15J16-1T3AT belonged to the family Cytophagaceae, phylum Bacteroidetes, and was most closely related to ‘Larkinella harenae’ 15J9-9 (95.9% similarity), Larkinella ripae 15J11-11T (95.6%), Larkinella bovis M2TB15T (94.7%), Larkinella arboricola Z0532T (93.9%), and Larkinella insperata LMG 22510T (93.5%). Cells were rod-shaped, Gram-stain-negative, aerobic, and nonmotile. The isolate grew on NA, R2A, TSA, but not on LB agar. The strain was able to grow at temperature range from 10°C to 30°C with an optimum at 25°C and pH 6–8. Menaquinone MK-7 was the predominant respiratory quinone. The major cellular fatty acids comprised C16:1ω5c (48.6%) and C15:0 iso (24.1%). Phosphatidylethanolamine, phosphatidylserine, and an unidentified lipid were the major polar lipids. The G + C content of the genomic DNA was 49.5 mol%. Strain 15J16-1T3AT could be distinguished from its closest phylogenetic neighbors based on its phenotypic, genotypic, and chemotaxonomic features. Therefore, the isolate is considered to represent a novel species in the genus Larkinella, for which the name Larkinella roseus sp. nov. is proposed. The type strain is 15J16-1T3AT (= KCTC 52004T = JCM 31991T).

Jejuia marina nov., isolated from gravel adjacent to Geommeolle beach on Udo Island, South Korea

A bacterial strain, JH03T, was isolated from gravel adjacent to Geommeolle beach on Udo Island, South Korea. The cells were Gram-stain-negative, aerobic, non-motile and rod shaped. The ranges of temperature, pH and NaCl concentration for growth of the bacterium were 10–45xa0°C, pH 6.0–9.5 and 0.5–5.0xa0% (w/v), respectively. The major fatty acids of the bacterium were iso-C15:0 (15.4xa0%), iso-C15:1 G (14.1xa0%), iso-C16:0 3-OH (14.1xa0%), iso-C17:0 3-OH (11.5xa0%) and anteiso-C15:0 (11.3xa0%). The major isoprenoid quinone was MK-6. The polar lipids included phosphatidylethanolamine, two unidentified amino lipids and three unidentified lipids. The DNA G+C content was 34.2xa0mol%. The phylogenetic analysis of the 16S rRNA gene sequences showed that strain JH03T was most closely related to Jejuia pallidilutea EM39T (96.5xa0% sequence similarity). Based on the polyphasic analysis, strain JH03T is a novel species of the genus Jejuia, for which the name Jejuia marina sp. nov. is proposed. The type strain is JH03T (=xa0KCTC 42342Txa0=xa0JCM 30601T).

A Pilot Study on the Application of Acoustic Data Collected from a Korean Purse Seine Fishing Vessel for the Chub Mackerel

This paper describes the first use of acoustic data collected during normal fishing operations from a South Korean commercial fishing vessel. Acoustic data (120xa0kHz) were collected from a purse seine fishing vessel while targeting chub mackerel (Scomber japonicus) between 13 September and 7 October 2014 in the southern West Sea and near Jeju Island. Acoustic backscatter data from 21 fishing events were used to delineate fish school characteristics and to estimate the chub mackerel biomass which was compared with the catch. With regard to the fish school description, the volume back scattering strength (SV) and thickness of the fish schools presented differently. The average and standard deviation of SV was −47.3u2009±u20092.1xa0dB. The fish lengths varied greatly and some schools were inordinately long (average and standard deviation length of 137.0u2009±u2009329.6xa0m). The fish school area largely altered. The average distributional depth and the distance between fish school and sea bottom were 31.8xa0m and 42.7xa0m, respectively, indicating that the fish schools attracted by light were mainly located close to the water surface. On average, the chub mackerel biomass was 1.7 times larger than the catch. The correlation between the chub mackerel biomass and the catch was low positive (ru2009=u20090.3, pu2009<u20090.05). This paper presented that available echo sounders installed fishing vessels can be used for helping in the chub mackerel resources management in South Korea.

Characterization of Frequency and Aggregation of the Antarctic Krill (Euphausia superba) Using Acoustics

In this study, the dB difference and characteristics of krill swarms inhabiting Subarea 48.1, which includes the west and south of the South Shetland Island and the Elephant Island peripheries, were estimated to distinguish Antarctic krill, using acoustics. From April 13 to 24, 2016, acoustic data were collected along 24 survey lines using the frequencies 38 and 120 kHz, and middle trawling was performed at 7 stations. Using the difference between the dB values of two volume backscattering strength (Sv) frequencies (38 and 120 kHz), a clear acoustic distinction could be made between Antarctic krill (4.9 to 12.0 dB) and fish (−4.0 to −0.2 dB). The distributions and mean Sv of krill swarms in the Elephant Island peripheries and south of South Shetland Island were higher than those in the west of South Shetland Island. The mean length/ height ratio of krill swarms in the west of the South Shetland Island (64.5) was higher than that in the south (35.9) and the Elephant Island peripheries (33.8), with the length of the aggregations exceeding their height. Most krill swarms were distributed between the surface layer (less than 10 m below sea level) and within 200 m of water depth. These results are expected to serve as baseline data for evaluating krill density and biomass by distinguishing them from fish, using acoustics.