The induction of maturation of female American eels through hormone injections

Edel, R. K.

doi:10.1007/bf01611801

Cited by 20 publications

(13 citation statements)

References 7 publications

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“…Therefore, these successes may mostly depend on using sexually advanced eels. Meanwhile, there is no attempt to induce maturation in wild yellow Japanese eels so far, although there are some attempts in A. anguilla and A. rostrata 13,16 . Hormonal treatments in yellow eels of these two species gave only a slight gonadal development, but not a complete maturation, 13,16 corresponding well with the present study's results.…”

Section: Discussionsupporting

confidence: 88%

“…These varying conditions may affect the feasibility of induced maturation. Attempts to induce maturation by exogenous hormones in wild silver eels of some temperate species indicated that silver eels respond well to the hormones and they can produce well‐matured eggs 4,13–15 . By contrast, in wild yellow A. anguilla and A. rostrata , hormonal treatments gave only a slight gonadal development 13,16 .…”

Section: Introductionmentioning

confidence: 99%

“…4,[13][14][15] By contrast, in wild yellow A. anguilla and A. rostrata, hormonal treatments gave only a slight gonadal development. 13,16 However, there is no detailed study to examine the relationship between the silvering state and the success of induced maturation and spawning in the Japanese eel. Especially, it is not known whether hormonal treatments can induce gonadal development in eels of intermediate type between typical yellow and silver eels, 12,17 or a more sexually advanced silver eel such as eels caught in the East China Sea 18 or Mikawa Bay 12 during their spawning migration.…”

Section: Introductionmentioning

confidence: 99%

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Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica

Okamura¹,

Yamada²,

Horie³

et al. 2008

Fisheries Sci

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The effects of silvering state of wild female Japanese eels Anguilla japonica on the success of induced maturation and the following spawning were examined. Thirty-eight females, collected in Mikawa Bay, were divided into four stages based on their silvering state: yellow (Y1), late-yellow (Y2), silver (S1) and late silver eels (S2). Despite injections of salmon pituitary extract (SPE) through the standard technique, Y1 and Y2 eels did not respond to the treatment with undeveloped gonad (gonad-somatic index [GSI]: 0.3-0.9), and all these females died by 5 weeks, probably due to an abnormal physiological condition. Most S1 (81%) and S2 eels (100%) matured completely (GSI: 17.8-51.4), and finally spawned successfully (69% for S1, 89% for S2). S2 eels fully matured with oocytes of over 750 mm in diameter by significantly smaller number of injections of SPE (5-6 times) than the case of S1 eels (6-8 times). The amount of eggs released by S2 eels (0.65 Ϯ 0.11 g/fish per body weight [BW]) was significantly larger than those by S1 eels (0.54 Ϯ 0.09 g/fish per BW). There was no difference in fertilization and hatching rates between eggs released by S1 eels and those of S2 eels. These results indicate that the success of induced maturation and spawning in wild female Japanese eels depends on their silvering state, and matured eggs can be obtained efficiently through the use of S2 eels rather than other stages.KEY WORDS: egg quality, exogenous hormone, fertilization, hatching, silver eel, silvering index, wild eel, yellow eel.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica

Okamura¹,

Yamada²,

Horie³

et al. 2008

Fisheries Sci

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“…The highest GSI values recorded for female Japanese eels, A. japonica, treated with salmon pituitary extract, were around 70 (Yamamoto and Yamauchi, 1974;Sugimoto et al, 1976). The highest GSI reported for female American eels, A. rostrata, treated with cPs, was 44.8 (Edel, 1975). No GSIs were given in the literature for A. australis and A. dieffenbachi (Lokman and Young, 2000).…”

Section: Discussionmentioning

confidence: 91%

Gonad development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.)

Ginneken

Vianen²,

Muusze³

et al. 2005

Animal Biol

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Gonadal development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.) was studied. Treatment of males with Human Chorionic Gonadotropin (HCG; 1 IU g/week) resulted in a Gonado-Somatic Index (GSI) of 10.88 ± 3.39 and spermiation. Treatment of females with carp Pituitary suspension (cPs) (20 mg cPs/kg body weight per week) resulted in oogenesis with a GSI of 20.0 ± 11.3 (n = 7), and the number of eggs per female was 1874 * 10 3 ± 1116 * 10 3 ; (n = 7). Ovulation of the females was induced with 17α, 20β dihydroxyprogesteron (DHP) at 2 µg/g bodyweight. Eggs of European eel were found to be non-sticky and typically pelagic. Maximum speed of eggs rising to the surface in a water column was 2.24 ± 0.33 metres (m) per hour (h). To study behaviour in a qualitative way, two females were used together with three groups of three males. During a 283 minute (min) observation of the two females, we observed female-female interaction: 'lethargic behaviour' (33.6%) vs. 'cruising together' (66.4%). In the period when males and females were together (188 min), we observed 'approaching the head region of the female' (57.7%), 'touching the operculum' (39.4%), or 'approaching the urogenital area' (2.9%) by the males (total 725 seconds (s)). Sperm release in the presence of a female took 115 s of the total approaching time of 725 s (15.9%), while in the case of male-male interaction this was only 15 s of the total period of 116 s (12.9%). Induced spawning behaviour of eels was collective and simultaneous, corresponding to spawning in a group. This is the first time group spawning behaviour has ever been observed and recorded in eels.

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“…However, the modest increase in the relative concentration of 18 : 1n9 in the plasma of more mature eels of Quebec City and Kamouraska suggests that either 18 : 1n9 is not as important in the development of eel ovaries as in other teleost studied thus far, or the greatest ovarian development has not yet occurred at this point in the migration. Artificial maturation experiments in which (I G ) _50%, with the bulk of this development occurring late in the maturation process, would tend to support the latter (Edel, 1975;Boetius & Boetius, 1980). The relatively low levels of oleic acid probably reflects an increased importance of  s    other fatty acids at this point in the migration, particularly the saturate 16 : 0, the monene 16 : 1 and the polyunsaturate 22 : 6n3.…”

Section: Nefa Levelsmentioning

confidence: 97%

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

Ccottrill

McKinley

Kaak

et al. 2001

Journal of Fish Biology

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American eels Anguilla rostrata, collected from three distinct locations along the St Lawrence River (Lake St Lawrence, Quebec City and Kamouraska), were thought to consist entirely of out-migrating adults at Quebec City and Kamouraska and of both resident and migrants at Lake St Lawrence. The mean plasma levels of 17 -oestradiol closely paralleled the trend observed with gonadosomatic index (I G ) and oocyte development. The highest levels of 17 -oestradiol and I G were observed in Quebec City and Kamouraska, while the levels observed in the resident eels from Lake St Lawrence were very low. Generally, the concentration of total plasma non-esterified fatty acids (NEFA) appeared to follow the trend of 17 -oestradiol and I G and increased with sexual maturity. However, the most sexually mature group, eels from Kamouraska, had the lowest total plasma NEFA levels. The reason for the drop is not clear at present. In addition, a number of shifts in the plasma NEFA profiles of American eels did occur during their migration in a downstream direction, with several fatty acids either increasing or decreasing in relative abundance. The ratio of n3 : n6 fatty acids declined with increasing sexual maturity as most n3 fatty acids became less abundant. Although the correlation between gonadal development and the relative concentration of individual fatty acids was not always clear, both arachidonic acid (20 : 4n6) and docosahexaenoic acid (22 : 6n3) were significantly higher in the plasma of out-migrating adults than in resident yellow phase eels. 2001 The Fisheries Society of the British Isles

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The induction of maturation of female American eels through hormone injections

Cited by 20 publications

References 7 publications

Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica

Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica

Gonad development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.)

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

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