Study

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

  • 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.

Actions

This study is summarised as evidence for the following.

Action Category

Breed eels in captivity

Action Link
Eel Conservation in Inland Habitats
  1. 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)

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 22

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the Evidence Champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust