Changes in fertilization and hatching rates with time after ovulation induced by 17, 20β-dihydroxy-4-pregnen-3-one in the Japanese eel, Anguilla japonica
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Published source details
Ohta H., Kagawa H., Tanaka H., Okuzawa K. & Hirose K. (1996) Changes in fertilization and hatching rates with time after ovulation induced by 17, 20β-dihydroxy-4-pregnen-3-one in the Japanese eel, Anguilla japonica. Aquaculture, 139, 291-301.
Published source details Ohta H., Kagawa H., Tanaka H., Okuzawa K. & Hirose K. (1996) Changes in fertilization and hatching rates with time after ovulation induced by 17, 20β-dihydroxy-4-pregnen-3-one in the Japanese eel, Anguilla japonica. Aquaculture, 139, 291-301.
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This study is summarised as evidence for the following.
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Breed eels in captivity Action Link |
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Breed eels in captivity
A replicated study (year not stated) at a research facility in Japan (Ohta et al. 1996) found that artificially fertilized Japanese eel Anguilla japonica eggs had variable fertilization and hatching rates, and fertilizing eggs immediately after ovulation led to higher rates compared to fertilizing after 6–9 h. Statistical significance was not assessed. Overall, 1–90% of eggs/female were successfully fertilized and 0–48% hatched. When eggs were collected from females at the first detection of ovulation, higher rates of fertilization (1–90%) and hatching (0–48%) were observed compared to when eggs were collected 6–9 h after ovulation (fertilization: 1–15%, hatching: 0–2%). Thirteen captive-reared female eels were given 9–12 weekly injections of salmon pituitary extract followed by a hormone injection (17,20β-dihydroxy-4-pregnen-3-one) to induce ovulation. Rearing temperatures were then increased from 20 to 22.5°C. Eggs were collected from 11 ovulated females at 3 h intervals for 6–9 h and mixed with diluted semen from a captive male. Six samples (each containing an average of 89 eggs) from each fertilization were placed in petri dishes with seawater, and incubated at 23°C. Average fertilization rates were estimated after 3–4 h, and hatching rates after two days (both for three samples/female/collection time).
(Summarised by: Anna Berthinussen)
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