• 제목/요약/키워드: Aquatic net

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한국 서해안 꽃게, Portunus trituberculatus (Miers, 1876)의 난 성숙과 산란 (Gonad Maturation and Spawning of the Blue Crab, Portunus trituberculatus (Miers, 1876) from the West Sea of Korea)

  • 서형철;장인권;조영록;김종식;김봉래
    • 한국수산과학회지
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    • 제42권1호
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    • pp.48-55
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    • 2009
  • The gonad maturation and spawning of blue crab, Portunus trituberculatus (Miers, 1876) using samples caught by trammer net in the western coast of Korea from January to December. The gonadosomatic index (GSI) showed the highest value of 15.0 in June and lowest value of 1.29 in August. Hepatosomatic index (HSI) showed the lowest in the spawning season from June to July. Thereafter, from August the value started to increase to 5.77 in December, showing an adverse trend against GSI. In the histological studies of the female reproductive organ, the gonad filled with primary oocytes from January to February and secondary oocytes in May. The female gonads mature from June, and mature and immature groups could be distinguished from December to February or March. In August, female developed another cycle of gonad development, showing new primary oocytes in the gonads again. Some of female crabs had receptaculum filled with already active sperm cells in it from March to May. In the time of August to September, almost all the females had the sperm sacs in the receptaculum. From the result, the coupling period estimated from August to September. Total RNA and DNA values of the crabs were highest in May (2.51, $0.57{\mu}g/mg$). The DNA value remained unchanged except for the value in May ($0.09-0.13{\mu}g/mg$). while RNA value was lowest in January ($1.08{\mu}g/mg$). The RAN/DNA ratio was the lowest (6.23%) in May and highest (18.05%) in July. The value of correlations coefficient between body weight and fecundity of the crabs was higher that of between carapace width and fecundity.

Colonization and community changes in benthic macroinvertebrates in Cheonggye Stream, a restored downtown stream in Seoul, Korea

  • Shin, Il-Kwon;Yi, Hoon-Bok;Bae, Yeon-Jae
    • Journal of Ecology and Environment
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    • 제34권2호
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    • pp.175-191
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    • 2011
  • Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionally restored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrates were quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total) increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower values in the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstream reaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta, Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributors in the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowers dominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout the stream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominated in the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation procedures demonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the Gapyeong Stream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physical environmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and total phosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in the study streams.

뱀장어 수생진균(水生眞菌), Saprolegnia didina Type I의 실험적(實驗的) 감염(感染) (Experimental Inection with Saproloenia diclina Type I in Eels(Anguilla japonica))

  • 민홍규;박남용;하타이 키시오
    • 한국어병학회지
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    • 제3권2호
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    • pp.61-66
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    • 1990
  • 수생균병(水生菌病)의 원인균(原因菌)의 하나인 Saprolegnia diclina Type I 을 뱀장어에 실험적(實驗的)으로 감염(感染)시켜 감염(感染) 기전(機轉)과 균사체(菌絲體)가 체표(體表)의 표피(表皮)와 진피(眞皮)에 나타나는 소견(所見)을 병리학적(病理學的)으로 조사(調査)하였다. 1. 뱀장어를 물에서 건져 그물로 처리한 A, B군(群)에서는 실험적(實驗的)으로 감염(感染)되지 안했으나 인공적(人工的)으로 피부점액(皮膚粘液)을 제거(除去)한 C군(群)에서는 심한 감염(感染)이 관찰(觀察)되었다. 2. 감염어(感染魚)의 체표(體表)에서 채취(採取)한 진균류(眞菌類)는 무격벽(無隔壁)으로 분지(分枝)하며 간접(間接) 발아(發芽) 양식이어서 S. diclina Type I으로 동정(同定)되었다. 3. 어체(魚體) 전반(全般)에 면모상(綿毛狀)의 균사체(菌絲體)가 관찰(觀察)되었고 출혈반(出血斑)을 수반(隨伴)한 병소(病巢)가 형성(形成)되었다. 4. 병소내(病巢內)에는 균사체(菌絲體)가 표피(表皮)와 진피(眞皮)에 신장(伸長) 분포(分布)되어 있었고 특(特)히 피부(皮膚)의 표피층(表皮層)에는 심(甚)한 출혈(出血), 세포(細胞)의 변성(變性), 괴사(壞死_ 및 일부(一部) 점액세포(粘液細胞)는 심(甚)하게 종대(腫大)되어 있었다.

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먹이에 따른 물가자미 (Eopsetta grigorjewi) 치어의 에너지 수지 (Energy Budget of Snotted Halibut Juvenile, Eopsetta griorjewi with Two Different Prey Items)

  • 이선식;한경남;윤원득
    • 한국수산과학회지
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    • 제36권4호
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    • pp.358-364
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    • 2003
  • Gross energy intake fecal, nitrogen excretory and metabolized energy of snotted halibut juvenile, Eopsetta grigorjewi, fed on Tigriopus iaponicus (Group A) and the enriched Artemia nauplii (Group B), were quantitatively investigated and represented as balance equations of energy and material. Absorption efficiency (AE), gross conversion efficiency $(K_1)$ and net conversion efnciency $(K_2)$ were also estimated to understand the changes in efficiency by the prey Gross energy intake, fecal, nitrogen excretory, metabolized and growth energy of Group A were $2.790\pm0.247,\;0.495\pm0.046,\;0.018\pm0.003,\;0.214\pm0.047\;cal\;mg^{-1}\;day^{-1}$ and $2.063\;cal\;mg^{-1}\;day^{-1},$ respectively. The same parameters of Group B were $4.801\pm0.165,\;0.579\pm0.031,\;0.055\pm0.010,\;0.306\pm0.048\;cal\;mg^{-1}\;day^{-1}$ and $3.861\;cal\;mg^{-1}\;day^{-1},$ respectively. Energy budget of Group A and B were represented as 100 C= 7.67 M+17.7 F+0.65 U+73.94 G and 100C=6.37 M+ 12.1 F+1.15 U+80.42 G, respectively, where C, M, F, U, and G represent gross energy intake, metabolized energy, fecal energy, nitrogen excretory (non-fecal) energy and growth energy, respectively. AEs of Croup A and B were $81.52\pm1.89,\;86.79\pm0.70\%,$ respectively, with significant difference at p=0.01 level. However, $K_1\;and K_2$ of Group A and B showed no significant difference at p=0.01 level, with $74.21\pm6.57,\;80.48\pm2.76\%\;and\;91.17\pm7.26,\;92.74\pm2.69\%$ respectively. These results suggest that T. japonicus is a possible substitute for Artemia nauplii for the snotted halibut juvenile.

1992년 하계 득량만 서부해역의 조류 특성 (Tidal Current in the Western Part of Deukryang Bay in Summer 1992)

  • 이재철;노홍길;조규대;신상일;김상우;김상현
    • 한국수산과학회지
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    • 제28권1호
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    • pp.1-6
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    • 1995
  • 1992년 7월 1일부터 8월 7일까지 득량만의 수문리와 득량도 사이의 수심 약 5m 되는 천go역에서 2.5m의 수심에 자기 기록식 유속계를 계류하여 유속관측을 하였고 이 자료를 분석하였다. 관측기간 동안 바람은 매우 약했으므로 조류의 성질을 연구하는 데 적합한 자료가 획득되었다. 항류성분은 0.8cm/sec의 속도로 남남동 방향으로 흐르며 이는 득량도 동부 수로를 통하여 북향류가 필요하고 따라서 반시계 방향의 느린 순환이 일어난다는 것을 암시한다. 조류의 주축 방향은 북북동-남남서 방향이며 전체 분산의 $98.7\%$가 이 방향에 집중되어 있다. 이 유속의 역학적 에너지의 $91.2\%$ 정도는 반일주조이며 일주조 이상의 장주기 성분은 $2.5\%$ 에 불과한 반면에 비선형효과에 기인하는 천해조 성분은 $6.3\%$ 정도를 점유하였다.

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생태계 제어 시설물의 설계 및 배치 최적화(1) -연승식 양식시설의 계류력 특성 및 동요저감에 관한 연구- (Structural and Layout Design Optimization of Ecosystem Control Structures(1) -Characteristics of Mooring Force and Motion Control of the Longline Type Scallop Culturing Facility-)

  • 류청로;김현주
    • 한국수산과학회지
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    • 제28권1호
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    • pp.35-48
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    • 1995
  • To develop the optimal design method for the longline type scallop culturing facilities in the open sea numerical calculations and hydraulic model experiments are carried out for the stability and function optimization. Using the results for the motion and tension of the facilities, stable design concepts and effects of motion control system by vertical anchor and resistance discs art discussed. The results of this study that can be applied to the design are as follows: 1) Total external forces by design wave $(H_{1/3}\;=\;6,7\;m,\;T_{1/3}\;=\;12sec)$ at the coastal waters of Jumunjin for unit facility (one main line) are estimated to 5-20 tons, and required anchor weights are 10-40 tons in the case of 2-point mooring system. Though the present facilities are stable to steady currents, but is unstable to the extreme wave condition of return period of 10 years. 2) The dimensions and depth of array systems must be designed considering the ecological environments as well as the physical characteristics including the mooring and holding forces that are proportional to the length and relative depth of main line to wave length, and the number of buoys and nets. 3) Oscillation of the facility is influenced by water particle motion and the weight of hanging net, and is excited at both edge, especially at the lee side. To reduce the motion of the nets, the vertical anchoring system and the resistence disc method are recommended by the experimental results, 4) The damage of rope near the anchor by abrasion should be prevented using the ring-type connection parts or anchor chains.

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흰점독가시치 (Siganus canaliculatus)의 생식소 발달 및 생식주기 (Gonadal Development and Reproductive Cycle of the Rabbitfish (Siganus canaliculatus))

  • 황형규;박창범;강용진;이종하;노섬;이영돈
    • 한국수산과학회지
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    • 제37권5호
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    • pp.393-399
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    • 2004
  • Annual reproductive cycle of Siganus canaliculatus was studied based on monthly variation of gonadosomatic index (GSI) and histological changes of gonads. Samples were monthly collected by a set net along the southern coast of Jeju Island, Korea from January to December, 1996. Variation of the monthly mean GSI values showed similar trends in female and male. The GSI values increased from June and reached a peak in the spawning season in July $(9.65{\pm}1.96\;in\;females,\;10.00{\pm}4.27\;in\;males)$, and decreased rapidly thereafter. Female hepatosomatic index (HSI) values ranged from $1.26{\pm}0.22\;(in\;April)\;to\;2.34{\pm}0.39$ (in July), and male HSI values ranged from $1.27{\pm}0.21\;(in\;April)\;to\;1.87{\pm}0.30$ (in October). Annual reproductive cycle was classified into the following successive stages: in female, growing stage (from February to June), mature stage (from June to July), ripe and spawning stage (from July to August), recovery stage (from August to March); and in male, growing stage (from January to June), mature stage (from June to July), ripe and spent stage (from July to August), and recovery stage (from August to April). Based on these data, this species has a group-synchronous oocyte development and one spawning season a year.

Distribution Characteristics of Bottom Litter in Chinhae Bay, Korea

  • Kim Jong-Hwa;Kim Sam-Kon;Kim Jong-Kyu
    • Fisheries and Aquatic Sciences
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    • 제4권3호
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    • pp.150-158
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    • 2001
  • A study on the amount, distribution and item of bottom litter on the sea-bed was conducted by the bottom trawl net at 5 sections in Chinhae Bay over a year. The number and weight of litter found per unit of swept area (1 hectare) in each section were estimated as the range of 8.76-80.63 pieces, 3.51-108.39kg, respectively. The seasonal variation of high (Aug., '97) and low season (Feb., '98) in quantity was small, and it was about 2 times as the range of 24.58- 52.61 pieces/ha between them. But the weight variation between high (Apr., '98) and low season (Aug., '97) was very large, about 30 times as the range of 4.06-119.64kg/ha. The largest and second composition on the weight of bottom litter in Chinhae Bay are $76\%$ in other-litter with compound and bulky materials, and $93\%$ in fishing gear, respectively. The relationship between quantity and weight of bottom litter was not occurred due to the variety of specific gravity. Of the fishing gear, fishing nets was portioned to be 2.571kg/ha in weight and $84.9\%$ in composition. So these results prove that fishing nets were discarded as the most part of fishing gear during fishing activity in the bay. The largest composition of the soiled state classified into 3 styles in overall bottom litter was $69\%$ in very soiled state, and the second one of $28\%$ in the soiled state. On the other hand, new state is very small and portioned in $3.0\%$ of all. Chinhae Bay was estimated to be about 10 times in quantity and about 36 times in weight of Tokyo Bay. Therefore, these suggest that Chinhae Bay is a very serious polluted estuary caused by the bottom litter such as heavy and bulky wastes, fishing gear.

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The Frequency and Length Dependence of the Target Strength of the Largehead Hairtail (Trichiurus lepturus) in Korean Waters

  • HwangBo, Young;Lee, Dae-Jae;Lee, Yoo-Won;Lee, Kyoung-Hoon
    • Fisheries and Aquatic Sciences
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    • 제12권2호
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    • pp.152-161
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    • 2009
  • The largehead hairtail (Trichiurus lepturus) is one of the most common fisheries stocks in the East China Sea and the Yellow Sea. The species is caught using a variety of fishing tools, such as a stow net or a long line, as well as jigging and trawling. Scientific investigations have been conducted throughout the world to enable evidence-based estimations for the management and protection of the main fisheries biomass. For example, inshore and offshore hydro acoustic surveys are performed annually using bottom- and mid-water trawls around the Korean Peninsula. However, to date, no acoustic survey has been conducted to estimate fish size distribution, which is necessary to construct a data bank of target strength (TS) relative to fish species, length (L), and frequency. This study describes the frequency and length dependence of TS among fishes in Korean waters for the purpose of constructing such a TS data bank. TS measurements of the largehead hairtail were carried out in a water tank (L 5 m$\times$width 6 m$\times$ height 5 m) at frequencies of 50, 75, 120, and 200 kHz, using a tethering method. The average TS patterns were measured as a function of tilt angle, ranging from $-45^{\circ}$ (head down) to $+45^{\circ}$ (head up) every $0.2^{\circ}$. The length conversion constant ($b_{20}$) was estimated under the assumption that TS is proportional to the square of the length. In addition, in situ TS measurements on live largehead hairtails were performed using a split beam echo sounder.

경상북도 후포와 강원도 장호에서 정치망으로 채집된 어류 종조성 비교 (Comparison of Fish Species Composition Collected by Set Net at Hupo in Gyeong-Sang-Buk-Do, and Jangho in Gang-Won-Do, Korea)

  • 강정하;김이경;박중연;김진구;유정화;강충배;박정호
    • 한국수산과학회지
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    • 제47권4호
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    • pp.424-430
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    • 2014
  • Two major temperature fronts, the Subpolar (Gosung, Gang-won-do; $38^{\circ}-41^{\circ}N$) and Thermal (Jukbyun, Gyeong-sang-buk-do; $36^{\circ}-37^{\circ}N$) fronts, are found in the East Sea along the east coast of Korea. These are located roughly where the Tsushima Warm Current and North Korea Cold Current intersect. To clarify the effect of the Thermal Front, we investigated seasonal variation in fish species composition using set nets in two areas located north (Jangho, Gang-won-do) and south (Hupo, Gyeong-sang-buk-do) of Jukbyun, Gyeong-sang-buk-do, and compared the sea water temperature and salinity. We collected a total of 38 fish species in Hupo and 25 in Jangho. Trachurus japonicus was the most common species at both sites, but the subdominant species differed. At Hupo, the subdominant species were Konosirus punctatus and Diodon holocanthus, whereas Clupea pallasii and Scomber japonicus were subdominant at Jangho. Based on Froese and Pauly (2014), subtropical fishes accounted for 55% of fish in Hupo but only for 33% in Jangho. The difference in fish species composition was most obvious in May and August. According to the Korea Hydrographic and Oceanographic Administration, sea surface temperature and salinity were slightly higher at Hupo than at Jangho. Our findings suggest that the oceanographic boundary resulting from the Thermal Front near Jukbyun, Gyeong-sang-bukdo may have a major effect on the distribution of migratory fish species.