Abstract
For efficient production of Japanese eel Anguilla japonica eggs, knowledge of the status of the sexual maturity of potential broodstock females is important because this status directly influences the time required to produce mature eggs by successive hormone doses. Here we apply an eye index (relative eye size) to evaluate the gonadal status of feminized A. japonica, which were induced by administration of estradiol-17β. Examination of gonad somatic and eye indexes of 267 feminized eels, cultivated for 12–56 months, revealed a significant correlation between these two indexes. Artificial maturation of 35 feminized eels showed that the number of hormone injections administered before ovulation was significantly lower as the eye index score increased, indicating availability of this noninvasive method of predicting sexual maturity of feminized eel. There was no correlation between eye index and fertilization rate, hatching rate, or larval survival rate, suggesting that sexual maturity before hormonal treatment does not affect egg quality.
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References
Acou A, Boury B, Laffaille P, Crivelli AJ, Feunteun E (2005) Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla). Arch Hydrobiol 164:237–255
Acou A, Poizat G, Crivelli AJ (2006) Errors in ocular index measurements in European eel Anguilla anguilla (L.). Ecol Freshw Fish 15:578–582
Boëtius I, Boëtius J (1980) Experimental maturation of female silver eels, Anguilla anguilla. Estimate of fecundity and energy reserves for migration and spawning. Dana 1:1–28
Cottrill RD, McKinley RS, Van Der Kraak G (2002) An examination of utilizing external measures to identify sexually maturing female American eels, Anguilla rostrata, in the St. Lawrence River. Environ Biol Fish 65:271–287
Dou SZ, Yamada Y, Okamura A, Shinoda A, Tanaka S, Tsukamoto K (2007) Observations on the spawning behavior of artificially matured Japanese eels Anguilla japonica in captivity. Aquaculture 26:117–129
Durif C, Dufour S, Élie P (2005) The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage. J Fish Biol 66:1025–1043
Han YS, Liao IC, Huang YS, He JT, Chang CW, Tzeng WN (2003) Synchronous changes of morphology and gonadal development of silvering Japanese eel Anguilla japonica. Aquaculture 219:783–796
Horie N, Utoh T, Mikawa N, Yamada Y, Okamura A, Tanaka S, Tsukamoto K (2008) Influence of artificial fertilization methods of the hormone-treated Japanese eel Anguilla japonica upon the quality of eggs and larvae. Nippon Suisan Gakkaishi (Bull Jpn Soc Sci Fish) 74:26–35 (in Japanese)
Ijiri S, Kayaba T, Takeda N, Tachiki H, Adachi S, Yamauchi K (1998) Pretreatment reproductive stage and oocyte development induced by salmon pituitary homogenate in the Japanese eel Anguilla japonica. Fish Sci 64:531–537
Kagawa H, Tanaka T, Ohta H, Okuzawa K, Iinuma N (1997) Induced ovulation by injection of 17,20β-dihydroxy-4-pregnen-3-one in the artificially matured Japanese eel, with special reference to ovulation time. Fish Sci 63:365–367
Ohta H, Kagawa H, Tanaka K, Okuzawa K, Iinuma N, Hirose K (1997) Artificial induction of maturation and fertilization in the Japanese eel, Anguilla japonica. Fish Physiol Biochem 17:163–169
Oka HP (1979) Studies on the artificial maturation in the Japanese eel, Anguilla japonica-III: on the relation between the changes in body weight and oogenesis during the course of maturation. Bull Shizuoka Pref Fish Exp Stn 13:101–111
Okamura A, Yamada Y, Yokouchi K, Horie N, Mikawa N, Utoh T, Tanaka S, Tsukamoto K (2007a) A silvering index for the Japanese eel Anguilla japonica. Environ Biol Fish 80:77–89
Okamura A, Yamada Y, Horie N, Utoh T, Mikawa N, Tanaka S, Tsukamoto K (2007b) Effects of water temperature on the early development of the Japanese eel Anguilla japonica. Fish Sci 73:1241–1248
Okamura A, Yamada Y, Horie N, Utoh T, Mikawa N, Tanaka S, Tsukamoto K (in press) Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica. Fish Sci
Pankhurst NW (1982) Relation of visual changes to the onset of sexual maturation in the European eel Anguilla anguilla (L.). J Fish Biol 21:127–140
Tachiki H, Nakagawa T (1993) Induction of spawning in female cultured eel Anguilla japonica. Bull Aichi Fisher Res Inst 1:79–81 (in Japanese)
Tachiki H, Nakagawa T, Tamura K, Hirose K (1997) Effects of oral administration of estradiol-17β to young on gonadal sex and growth of Japanese eel Anguilla japonica. Suisan Zousyoku (Aquacult Sci) 45:61–66 (in Japanese)
Tanaka H, Kagawa H, Ohta H, Unuma T, Nomura K (2003) The first production of glass eel in captivity: fish reproductive physiology facilitates great progress in aquaculture. Fish Physiol Biochem 28:493–497
Tatsukawa K (2003) Eel resources in East Asia. In: Aida K, Tsukamoto K, Yamauchi K (eds) Eel biology. Springer, Tokyo, pp 293–298
Unuma T, Kondo S, Tanaka H, Kagawa H, Nomura K, Ohta H (2004) Determination of the rates of fertilization, hatching and larval survival in the Japanese eel, Anguilla japonica, using tissue culture microplates. Aquaculture 241:345–356
Yamada S, Hori K, Seoka M (2006) Toward the improvements of broodfish management and egg quality of the Japanese eel, Anguilla japonica, for larviculture—egg collection from young broodfish and effects of broodfish diet on egg fatty acid contents. Bull Fish Res Agen 5(Suppl.):33–37 (in Japanese)
Acknowledgements
We thank Drs H. Tanaka and T. Unuma of the National Fisheries Agency of Japan for their advice and teaching us how to perform the microplate method of evaluating eel egg quality. This study is a contribution (No. 35) from the IRAGO Institute Co., Ltd.
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Okamura, A., Oka, H.P., Horie, N. et al. Assessing sexual maturity of feminized Japanese eel Anguilla japonica by measuring eye size. Aquacult Int 17, 91–99 (2009). https://doi.org/10.1007/s10499-008-9172-z
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DOI: https://doi.org/10.1007/s10499-008-9172-z