• Title/Summary/Keyword: eel

Search Result 635, Processing Time 0.026 seconds

Comparative study on growth of leafy vegetables grown in a hybrid BFT-aquaponics using Japanese eel, Anguilla japonica and hydroponics

  • Lee, Dong-Hoon;Kim, Jeong-Dae
    • Fisheries and Aquatic Sciences
    • /
    • v.24 no.7
    • /
    • pp.260-275
    • /
    • 2021
  • Aquaponics is a cultivation system that combines aquaculture and agricultural hydroponics. This study investigated the productivity of leafy vegetables cultivated in the hybrid biofloc technology-aquaponics (HBFT-AP) using Japanese eel fed two kinds of diets (Mash, commercial powdered feed and extruded pellet [EP]) and hydroponics (HP).The mash was fed to the fish in a type of a dough mixed with water for 6 weeks (Exp1) and switched to the EP containing 2.7% monobasic potassium phosphate (MKP) for subsequent 6 weeks (Exp2). Leafy vegetables of 8 cultivar were employed in the experiment and water quality [dissolved oxygen (DO, mg/L), pH, water temperature (℃), electrical conductivity (EC; ㎲/cm), turbidity (NTU), TAN (NH3 + NH4+) (mg /L), NO2-N (mg/L), NO3-N (mg/L) and PO4-P (mg/L)] was measured 6 times a week. Leafy vegetable productivity (HBFT-AP vs HP) was compared in respective experiment, which was similar or somewhat higher in HBFT-AP. During the 12-week feeding trial, concentrations of nitrite (NO2-N) and phosphorus (PO4-P) were kept low in variability while total ammonia nitrogen (TAN) and NO3-N levels increased with time in HBFT-AP. At the end of two feeding trials, values of weight gain (WG, %), feed efficiency (FE, %), specific growth rate (SGR, %) and protein efficiency ratio (PER) were higher in Exp2 than in Exp1. As well, higher values in hematocrit (PCV, %), plasma K (mEq/L) and inorganic phosphorus (mg/dL) were found (p < 0.05) in Exp2 where fish were fed the EP (EP: 38.60%, 2.80 mEq/L and 7.04 g/dL; Mash: 33.20%, 1.95 mEq/L and 5.50 g/dL). Leafy vegetables in HBFT-AP using Japanese eel fed the EP with MKP 2.7% had a productivity similar (4 kinds of cultivar) or somewhat higher (4 kinds of cultivar) compared to those in HP. Also, Japanese eel fed the EP showed higher values of Pi (m/dL) and K (mEq/L) in plasma compared to those fed commercial powder diet.

Morphogenetic Identification of Eel's Larva (Leptocephalus) Collected by Set net in Namhae, Korea (남해 정치망에서 채집한 엽상자어(Leptocephalus)의 형태 및 유전학적 특성)

  • Chang-Gi Hong;Kyeong-Ho Han
    • Journal of Marine Life Science
    • /
    • v.8 no.2
    • /
    • pp.128-135
    • /
    • 2023
  • The present study was tried to identify whether the eel's larva was close to a conger (Conger myriaster), a pipe conger (Muraenesox cinereus) or four species of Anguilla. Experimental fishes were collected by set net in the gulf of enggang, Namhae, Korea from May to June. Their morphological characteristics were compared with adult fishes of a conger, a pipe conger and four species of Anguilla. For genetic classification, DNA was isolated and amplified by using 12S rRNA and 16S rRNA primer set. The PCR products were direct sequencing in both directions. The nucleotide sequences were analyzed using softwares. As results of morphological measurement on eel's larva, the percentages of head length and preanal length against total length were similar with a conger. Based on the nucleotide sequences, the phylogenetic tree also revealed a close relationship to a conger. Therefore, eel's larva, caught in Namhae from May to June, was identified into a conger's larva.

Feeding Ecology of the White-spotted Conger Eel(Conger myriaster) in the Southern Sea of Korea (한국 남해 연안에 분포하는 붕장어(Conger myriaster)의 섭이생태)

  • Choi, Jung-Hwa;Choi, Sung-Hee;Kim, Jong-Bin;Park, Jeong-Ho;Oh, Chul-Woong
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.41 no.4
    • /
    • pp.282-288
    • /
    • 2008
  • Feeding ecology of the white-spotted conger eel Conger myriaster in the Southern Sea of Korea was examined. Specimens were caught monthly from January 2004 to December 2006. Primary prey items of C. myriaster included fish, shrimp, and crabs. C. myriaster exhibited a nocturnal feeding strategy and preyed upon a wide range of pelagic fish groups(e.g., Engraulis japonicus, Glossanodon semifasciatus, and Maurolicus muelleri). This species was also an opportunistic feeder that exploited the available prey in each area(i.e., fish in the A area and shrimp in the B area). The composition of the diet of C. myriaster exhibited seasonal fluctuations that were related to food availability during each season. The observed ontogenetic shifts in diet were relatively clear, despite substantial overlap between the 10 cm and 20 cm groups of C. myriaster.

Variation in the Vertebral Number of Sand-eel, Ammodytes personatus GIRARD (까나리의 생물학적 기초조사)

  • 전찬일
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.15 no.1
    • /
    • pp.1-3
    • /
    • 1979
  • The sand-eel, Ammodytes personatus GIRARD, "Kka-na-ri" is an important commercial fish inhabiting the coastal waters of Korea. The numbers of vertebrae (except urostyle) waR statistically analysezed based on the samples collected at three major fishing localitie" Jumunjin (East Sea), Geoje Island (southern coast) and Baegryeong Island (Yellow Sea) from May 1978 to June 1979. It was found that there was a very distinct difference in the numbers of vertebrae in the samples.rae in the samples.

  • PDF

Effects of Starvation, Water Temperature, and Water Flow on the Metamorphosis of Leptocephalus of Japanese Eel Anguilla japonica (절식, 수온 및 유속이 극동산 뱀장어(Anguilla japonica) 렙토세팔루스의 변태 유도에 미치는 영향)

  • Kim, Dae-Jung;Lee, Nam-Sil;Kim, Kyung-Kil;Chang, Dae-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.47 no.5
    • /
    • pp.597-602
    • /
    • 2014
  • We determined the effects of starvation, water temperature, and water flow on the onset of metamorphosis in leptocephali of the Japanese eel Anguilla japonica. Leptocephali larger than 50 mm (ca. 200 days old) were reared in 10-L tanks under different feeding, water temperature, and water flow regimes. Fasted leptocephali metamorphosed earlier and faster than did the fed ones. Metamorphosis was faster in the high water flow tank (1.2 L/min) than in the tank with flow at 0.6 L/min. The duration of metamorphosis was slightly shorter at $26^{\circ}C$ than at $23^{\circ}C$. To conclude, starvation induced the metamorphosis of artificially produced leptocephali larger than 50 mm TL. Increased water flow and water temperature both appear to induce and shorten metamorphosis.