Sung-Il Lee

Fishing investigation and species composition of the catches caught by a bottom trawl in the deep East Sea

. The rate of discarded catchesin situ was about 50%. The diversity indexes of 2005 and 2006 were 1.152 and 0.878, respectively, and theevenness indexes at those years were 0.752 and 0.583, respectively, which implied one dominant speciescaught in 2006.Key words : Deep sea, Bottom trawl, Species composition, Discarded fish, East Sea

Variations in species composition of demersal organisms caught by trawl survey in the East Sea

To examine species composition, abundance and biomass of demersal organisms in the East Sea, bottom trawlsurvey was conducted at 7 sea areas from 2005 to 2007. A total of 107 species were collected and werecomposed of 54 fish species, 16 crustacea, and 37 mollusks in the East Sea from 2005 to 2007. Yearlyabundance per area which caught by trawl survey in the East Sea from 2005 to 2007 ranged from a high of292,234inds./km

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.

Age and growth of the sandfish, Arctoscopus japonicus in the East Sea of Korea

were investigated from samples of the eastern seadanish seine and gill net fishery in the East Sea of Korea from February, 2004 to December, 2007. Ages weredetermined from annuli in otoliths and annuli were formed between December and February once a year.Also, the main spawning period was estimated to be between December and January, thus rings wereconsidered to be annual marks. For the relationship between fork length and total weight, a multiplicativeerror structure was assumed because variability in growth increased as a function of the length. Therelationship between fork length and total weight were TW0.0083FL

Development of artificial spawning seaweeds of the sandfish, Arctoscopus japonicus

began to attach the egg massto artificial spawning seaweeds when sea temperature dropped below 10in December, spawned heavilywhen it was around 8in January, and completed the behavior when it started to increase over 10inFebruary. The hatching period of eggs was estimated to be about 60 days. The middle position in artificialspawning seaweed had the highest number of egg masses and the diameter of the egg mass ranged from 25mmto 62mm. Based on the result for the effects, the artificial spawning seaweeds of

Age and Growth of Blackfin Flounder Glyptocephalus stelleri in the East Sea, Korea

Age and growth of Glyptocephalus stelleri in the East Sea of Korea were determined, from monthly samples of commercial catches, caught by the eastern sea Danish seine fishery in 2007. The annuli of G. stelleri are formed once a year, with the boundary between opaque and translucent zones forming in September. Relationships between total length (TL) and total weight (TW) were TW=0.002TL 3.392 (r 2 =0.970) for females and TW=0.002TL 3.335 (r 2 =0.961) for males. TLs at annuli formation in otoliths were backcalculated from the otolith-length relationship and were adjusted to von Bertalanffy growth curves to Lt=39.71(1 – exp (-0.152(t+1.156)) ) for females and Lt=32.16(1 – exp (-0.213(t+0.879)) ) for males. From the age of 3 yerars, females grew faster than males (P<0.05).

Determination factors for catch rate of the target species between circle hook and straight shank hook in the Korean tuna longline fishery

We conducted experiments to compare the catch rate of bigeye tuna and yellowfin tuna between circle hooks and straight shank hook in the Korean tuna longline fishery at the eastern and central Pacific Ocean from 2005 to 2007. We analyzed difference of fork length, survival and hooking location between a circle hook and a straight shank hook for both tunas, respectively. There was no difference in the mean fork length size of yellowfin tuna caught on the two type of hook but bigeye tuna was significant. In case of survival, there was no difference between two hook type, but the difference of hooking location was significant for both species. We also analyzed to find determinants of both tunas catch rate using generalized linear models (GLMs) which were used latitude, longitude, year, month, depth, hook type, bait type and so on as independent variables. Spatial factors, latitude and longitude, and temporal factors, year and month, affected catch rate of bigeye tuna and yellowfin tuna. And also, depth such as a marine environment factor was influenced on catch rate.

Energy budget of sandfish juvenile, Arctoscopus japonicus reared at different diet conditions and water temperature

In this study, energy budget was estimated to produce an efficient artificial seed. And it needs to enhance fisheries productivity of sandfish, A. japonicus. In order to estimate energy budget of the sandfish, A. japonicus juvenile fed on nonriched Artemia nauplii (NA) and the enriched Artemia nauplii (EA), of sandfish were reared at constant condition of seawater temperature of natural temperature (NT) and heated temperature (HT). During the reared period, energy used by the reared juveniles were calculated from estimates of data on ingestion, growth, oxygen consumption, nitrogen excretion and energy content. Energy budget of NT-NA, NT-EA, HT-NA and HT-EA were represented as 100C

Study on effects and strategies of Korean tuna purse seine fishery affected by conservation management measures of Western and Central Pacific Fisheries Commission

The WCPFC CMMs related to tropical tunas have been strongly restricting fishing capacity and operating activities of main fisheries, especially purse seine fishery. In terms of changes in fishing trend by implementing relevant measures of FAD set, the number of FAD set by Korean purse seine fleet showed a decreasing pattern with the lowest level of FAD set proportion among major distant water fishing nations. With regards to the FAD closure, there was no significant change in fishing effort but a drop in catch, especially bigeye tuna during the period of FAD closure. Moreover, it showed closely similar trends between the number of FAD set and bigeye tuna catch. In terms of measures related to the high sea area including a ban on fishing on the HSP and limitation of fishing days on the high sea by flag state, proportions of catch and effort on the high sea had sharply declined after implementing those measures. As relevant measures are expected to be strengthened, it should pay attention to change of coastal nations policies and focus on improving fishing efficiency of unassociated school set with multi-pronged efforts.

Seasonal Variations in the Species Composition of Fisheries Resources Caught by Trammel Net in the Uljin Marine Ranching Area, East Sea

Variations in the species composition, biomass and size distribution of fisheries resources in the Uljin marine ranching area were investigated using trammel nets at two stations (artificial reef and natural rocky area) from 2009 to 2010. During the survey, a total of 74 species were sampled with a mean density of 132 ind./net and mean biomass of 21.56 kg/net. In the natural rocky area, a total of 45 species were sampled at a mean density of 202 ind./net and mean biomass of 28.81 kg/net, while in the artificial reef area, samples included a total of 56 species, with means of 62 ind./net and 14.30 kg/net. The dominant species, comprising over 3% of the total number of individuals, were Suberites ficus (30.8%), Ovalipes punctatus (19.2%), Paralichthys olivaceus (11.7%), Pleuronectes herzensteini (4.7%), Kareius bicoloratus (3.5%), Pseudopleuronectes yokohamae (3.5%) and Eopsetta grigorjewi (3.0%). The dominant species, in terms of biomass, comprising over 5% of the total biomass, were P. olivaceus (22.1%), S. ficus (18.7%), O. punctatus (7.2%), Hexagrammos otakii (6.6%), P. yokohamae (5.7%), K. bicoloratus and P. herzensteini (5.3%). A cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on the Bray-Curtis similarity of fourth root transformed data for number of species and individuals, was divided into two groups: the artificial reef area (group A) and the natural rocky area (group B).