• The Korean Journal of Ecology
• /
• v.16 no.4
• /
• pp.489-499
• /
• 1993

Drifting aquatic insects were collected with using drift nets in the middle reaches of the Paenae stream. a tributary of the Naktong River in Korea, in four seasons from August 1989 to May 1990. During the study period, 6 orders and 31 families were collected. Drifted insects were the most diverse in autumn, while the number of collected individuals was the highest in spring. The abundant groups were the primary consumers such as Ephemeroptera and Diptera including Heptagenidae, Baetidae, and Chironomidae. The secondary consumers such as Plecoptera and Trichoptera, and the burrowers, Ephemeridae and Odonata were collected less than the primary consumers. Generally the first dominant species belonged to Ephemeroptera such as Pseudocloeotz sp., Heptagenia sp., and Baetis sp, In four seasons Ephemeroptera appeared more abundantly in drift(62%) than benthic samplings(33%). Diptera occurred similarly in drift and benthic samplings at 22%. Plecoptera and Trichoptera were collected at 4% and 11%, respectively, and appeared less than in benthic samplings. In functional groups collectors and scrapers were collected more than shredders and predators in drifts. In habit groups clingers and swimmers were present more than sprawlers and burrowers.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.15 no.1
• /
• pp.26-34
• /
• 1982

The East China Sea and the Yellow Sea are abundant in nutritions because of river inflows and are important as the nursery and spawning grounds of demersal and pelagic fishes. The remarkable thermal front between the Yellow Sea Bottom Cold Water and the Tsushima Warm Current is formed in this region, and the fluctuation of this front may affect the variation of the yellow croaker fishing ground. To investigate the mechanism of the yellow croaker fishing ground, the distribution ana seasonal change of the fishing ground are examined by using catch of stow net fishery (Fisheries Research and Development Agency, 1970-1979) and the water temperature data (Japan Hydrographic Association, 1978). The main fishing ground of yellow croaker was nine sea areas (rectangle of 30' latitude by 30' longitude) located at 40-150 nautical miles west and southwest of Jeju Island, the area of which occupies no more than $11\%$ of all fishing grounds, and it appeared that about $70\%$ of total catch of ten years was concentrated in this area. The main fishing periods were from March to May and September to October. The coefficients of variation of the catch for the main fishing ground were from 0.8 to 2.1 and the condition of all fishing grounds was generally unstable. The mean CPUE was 27kg/haul at the main fishing ground, while it was the largest on boundary area of the Yellow Sea Bottom Cold Water. It was found that the seasonal movement of fishing ground is related to the expansion and reduction of the Yellow Sea Bottom Cold Water ($10^{\circ}C$).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.13 no.4
• /
• pp.195-206
• /
• 1980

Fish were grown in a water recycling rearing system consisting of a filter system, of which the area is about $30\;m^2$ and the volume of filter gravels is about $15\;m^3$, 6 rearing and 2 supplementary tans about $7\;m^2$ of surface area each. The results for 180 days from April 18 to October 14,1980 are summarized as following: One rearing tank was used for main experiment stocked with an equal number, and weight of each Israeli strain and $F_1$, hybrid between this strain and Korean local strain of common carp. Gross total production was 461 kg with a net production of 395 kg, and the Israeli strain grew to about 8 times initial weight and the hybrid about 6 times. Based on an analysis of results of the above mentioned main experiment and the other miscellaneous fish grown in the remaining tanks, it was considered to be feasible to implement a commercial production in this system by improving parts of the system and adding a number of the units. A special problem seems to be an adoption of more effective aeration device when fish loading increases. A solid waste removal system was deviced by use of by-pass flow ana this system worked very efficiently in view of supply water economy. A serious problem encountered in this experiment was heavy outbreaks of the gill-fluke, Dactylogyrus sp. which was relatively easily eradicated with Dipterex or DDVP treatment in the first trials, but later on strains which were resistant to any of these chemicals appeared.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.1
• /
• pp.39-45
• /
• 1997

Subtidal zonation of a cumacean Bodotria biplicata was investigated in the sandy shore surf zone of Dolsando, southern Korea. Three replicate samples were taken with a sledge net at three sites, such as the surface and bottom of 1 m depth and waters edge, at hourly intervals over the neap and spring tide cycles on January 1993 (n=225). B. biplicata, the most dominant cumacean in this area, exhibited peak density at the bottom while about $0.6\%$ of total catch was collected at the surface. Mean density during the neap tide cycle was slightly higher than that during the spring tide cycle. The depth of subtidal zone influenced the total catch of B. biplicata. The changes in density were related to the depth of subtidal zone rather than day-night cycle or ebb-flood tide. The results obtained in this study suggest that the diel vertical migration is not distinct. During both neap and spring tide cycles, B. biplicata attained a density maximum at the same level of about 90 cm below lower low water (LLW). It is likely, therefore, that this species performs shore- and seaward horizontal migration fortnightly. The speed and distance of migration may be directly related to the beach slope and tide range. Ontogenetic differences in subtidal distribution were observed. Juveniles and manca larvae tended to occur lower areas than the adults. Such differences may reduce intraspecific competition for diets.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.17 no.3
• /
• pp.230-243
• /
• 1984

Larvae of fishes were collected at 26 stations in the Korea Strait, by horizontal towings using the fish larval net (Norpac) in the surface layer and by oblique towings using Isaac-Kid mid-water trawl in the mid-water layer in summer (July) and in autumn (November), in 1983. The towing speed was 1.5 knots. Of the larval fish examined, 3,529 individuals were identified to generic and specific levels. They belong to 27 families, consisting of 38 species in 37 genera. Unidentified were 114 specimens. The most abundant species was Engraulis japonica which occupied $88.5\%$ of the whole 3,645 individuals. Diaphus sp. took the second place with 50 individuals ($l.3\%$). Seasonally abundant species were in the order of Engraulis japonica, a Gobid, Trichiurus lepturus, and Diaphus sp. in summer, and in the order of Diaphus sp., Engraxlis japonica, Bothus sp., and a Ophichthid in autumn. Of these larvae, Engraulis japonica and Diaphus sp. continuously appeared from summer to Autumn. Champsodon sp., Diaphus sp. and Synagrops philippinensis were unrecorded species in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.2
• /
• pp.166-179
• /
• 1985

The seasonal distribution and migration of flying squid, Ommastrephes bartrami (LeSueur), in the North Pacific were studied by means of mantle length, surface temperature, and catch and effort data of the Korean drift gillnet fishery from 1980 to 1983. The water temperature for the best fishing ranged from $15^{\circ}\;to\;16^{\circ}C$ in May through July and from $13^{\circ}\;to\;18^{\circ}C$ in August through January. High densities of flying squid were found in the thermal fronts with $18^{\circ}C$ isotherm in August and with $15^{\circ}C$ isotherm in September. The densities of flying squid were higher in the western region than in the eastern region in the North Pacific. The high densities of flying squid in the northwestern Pacific were attributed to the high gradients of oceanographic properties in the region. Migration models for flying squid were hypothesized based on the monthly distributions of catch per unit net, mantle length compositions by statistical blocks, and the hydrographic features of the North Pacific. The large flying squid moved to the northern region and to the central Pacific region earlier than the small sized group in the northward migration period (from June to August). Flying squid begin the reverse southward migration from the Subarctic Frontal Zone in autumn with onset of cooling and the development of Oyashio Current. The large sized group starts their southward return migration from more northern waters than the small sized group but the former moves past the later ana reaches the spawing ground first.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.3
• /
• pp.271-277
• /
• 1985

As the fundamental studies for the population of Myagropsis myagroides, the effect of plant hormones on the regeneration for the primary, secondary lateral and receptacle segments were investigated. At high concentration($10^{-3}M\;and\;10^{-4}M$) of plant hormones inhibits from regenerating and lower concentrations advance the regeneration. The most effective concentrations of hormones on the primary lateral segments are $10^{-6}M$ of kinetine, IAA, NAA and $10^{-5}M$ of 2, 4-D in order, meanwhile in the secondary lateral segment $10^{-6}M$ of NAA, $10^{-8}M$ of kinetine, $10^{-7}M$ of IAA, and $10^{-5}M$ of 2, 4-D in order. The net regeneration rates of primary and secondary lateral segments which are measures by the wet weight are $124.1\%\;and\;228.9\%$, respectively. The influence of apical dominanace on the primary lateral segments decreases, on the other hand, increases in the secondary lateral segments because of the distance from the apex, Especially, the secondary lateral segments treated with below $10^{-5}M$ plant hormone are matures with receptacle of small branching by the regenerated branching.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.5
• /
• pp.294-305
• /
• 1989

Basedon statistical data of pomfret (Pampus spp.) catches by the stow net during $1970\~1985$, the distribution and migration of pomfrets and fishing conditions were investigated in relation to oceanographic conditions, in the East China Sea and the Yellow Sea. The main fishing grounds of Pomfrets were formed around the Great Yangtze Sand Bank which locates between the Cheju Island and the mouth of the Yangtze River. Its area occupied only 11 percent of all fishing grounds, and about 70 percent of total catch was found there. The coefficient of variation(CV) in catch was below 0.01 in the whole fishing grounds and that of tile main fishing grounds (14 fishing areas) was $0.001\~0.003$. This area was indicated markedly by the inflow of Yellow Sea Warm Current from spring to autumn, and this mixing area which formed the oceanic front among the China Continental Shelf Water, the Yellow Sea Bottom Cold Water and the Tsushima Warm Current. The pomfrets migrates to south-north according to the expansion and contraction of the Tsushima Warm Current including the Yellow Sea Warm Current and the Yellow Sea Bottom Cold Water. Therefore, it migrates to north of the Yellow Sea in summer and to southern part of the East China Sea in winter. The most frequent range of the water type for high catch was $10\~12^{\circ}C$ in temperature and $32.4\~33.4\%_{circ}$ in salinity. The ranges was occupied more than 70 percent of total catch on fishing season. The frequency range of the water type was not different between the abundant fishing periods and the poor fishing periods in terms of the maximum catches.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.2
• /
• pp.93-108
• /
• 1990

Complete larval development Orithyia sinica (Linnaeus) is composed of three zoeal ins-tars and megalopa. Survival of instals was higher in $20^{\circ}C$ than in ambient temperature. Intermolt period generally increased with the increase of number of instals, but a notable decrease was observed from Crab-5 to prepuerty molt instals(Crab-7). Zoeas and me-galopa reared at higher temperature regime were samller than those reared at lower temperature. No temperature effect was shown in the size of crab instals. Growth factors fluctuate with the increase of number of instals, but there was an overall trend of net decrease. Growth factor was $35.65\~41.4\%$ for zoeal instals, and they were $18.00\~30.91\%$ for crab instals.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.3
• /
• pp.237-246
• /
• 1995

Larvae of the freshwater shrimp, Macrobrachium nipponense were reared in the laboratory at constant condition $(25^{\circ}C,\;7\%o)$, and their feeding rate, oxygen consumption rate, and growth rate were measured in regular intervals of time during larval development. Regression equations describing rates of feeding, growth and respiration as functions of time during individual larval molt cycles were inserted in a simulation model in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Absolute values for feeding, growth, respiration and assimilation showed clear changes during the molt cycle, The absolute and specific values of respiration (R: R/C) showed small variation during the individual molt cycles. Significance of respiration in relation to growth (G) increased within the carbon budget, respiration rate (R/C) outbalanced growth rate (G/C) in late premolt. When the portion of metabolizable carbon is respired (R/G), metabolic coefficient was < 1 (i.e. R$(K_2)$ decreased concurrently, In cumulative carbon budget, total feeding was $491.54\;{\mu}g$ C/ind., assimilation was $85.3\%$, respiration was $47.7\%$, and growth was $37.6\%$ from hatching to postlarval stage.