Development of oocytes in a post-spawning Japanese eel Anguilla japonica Temminck & Schlegel in captivity

It is generally believed that parent freshwater eels (Anguilla sp.) die soon after spawning on the assumption that eels are a semelparous (or monocyclic) fish (spawn once at the last stage of life) like Pacific salmonids. However, we observed for the first time a post-spawning female Anguilla japonica again possessed developing oocytes reaching the final maturation stage in captivity five months after the last spawning even without hormonal treatment. Here we describe information on this female about its biological characteristics including gonadal histology and endocrine profiles. The data suggest that lowering water temperature for a period of time is one of the important factors influencing spontaneous gonadal development in this specimen. We also discuss the possibility of induced multiple spawning of this species in captivity.

[1]  K. Tsukamoto,et al.  Genetic identification and morphology of naturally spawned eggs of the Japanese eel Anguilla japonica collected in the western North Pacific , 2011, Fisheries Science.

[2]  G. van den Thillart,et al.  Influence of temperature regime on endocrine parameters and vitellogenesis during experimental maturation of European eel (Anguilla anguilla) females. , 2011, General and comparative endocrinology.

[3]  Michael J. Miller,et al.  Oceanic spawning ecology of freshwater eels in the western North Pacific , 2011, Nature communications.

[4]  T. Utoh,et al.  Studies on the technique of seed production of the common Japanese conger Conger myriaster , 2011 .

[5]  W. Hable,et al.  Artificial maturation, fertilization, and early development of the American eel (Anguilla rostrata) , 2010 .

[6]  K. Tsukamoto,et al.  Vertical migrations may control maturation in migrating female Anguilla dieffenbachii , 2010 .

[7]  K. Tsukamoto,et al.  Effects of silvering state on induced maturation and spawning in wild female Japanese eel Anguilla japonica , 2008, Fisheries Science.

[8]  A. Akazawa,et al.  Annual changes in ovarian development and plasma estradiol-17β level in reared female common Japanese conger, Conger myriaster , 2005, Fisheries Science.

[9]  W. Dekker.  A conceptual management framework for the restoration of the declining European eel stock , 2009 .

[10]  V. V. Ginneken,et al.  Effects of Swimming on Silvering and Maturation of the European Eel, Anguilla anguilla L. , 2009 .

[11]  K. Tsukamoto,et al.  Temperature influence on the spawning performance of artificially-matured Japanese eel, Anguilla japonica, in captivity , 2008, Environmental Biology of Fishes.

[12]  H. Matsubara,et al.  Serum steroid profiles in artificially maturing female Japanese eel, Anguilla japonica , 2005 .

[13]  A. Akazawa,et al.  Ovarian morphology of the Japanese eel in Mikawa Bay , 2004 .

[14]  H. Ohta,et al.  Artificial induction of maturation and fertilization in the Japanese eel, Anguilla japonica , 1997, Fish Physiology and Biochemistry.

[15]  Fran Saborido-Rey,et al.  Female Reproductive Strategies of Marine Fish Species of the North Atlantic , 2003 .

[16]  B. Pedersen.  Induced sexual maturation of the European eel Anguilla anguilla and fertilisation of the eggs , 2003 .

[17]  Hideki Tanaka.  Techniques for Larval Rearing , 2003 .

[18]  H. Kagawa.  Artificial Induction of Oocyte Maturation and Ovulation , 2003 .

[19]  K. Yamauchi,et al.  Oogenesis in the Japanese Eel, Anguilla japonica , 2003 .

[20]  Yuzuru Suzuki,et al.  Adequate interval of sGTH administration to induce vitellogenesis, and induction of ovulation by simultaneous administration of sGTH and 17α-hydroxyprogesterone in the Japanese eel , 2000 .

[21]  Yuzuru Suzuki,et al.  Use of an Emulsion Prepared with Lipophilized Gelatin for the Induction of Ovarian Maturation in the Japanese Eel Anguilla japonica , 1996 .

[22]  K. Yamauchi,et al.  Changes in serum steroid hormones and steroidogenic ability of ovarian follicles during artificial maturation of cultivated Japanese eel, Anguilla japonica , 1995 .

[23]  K. Asahina,et al.  Development of a Microtiter Plate Enzyme-linked Immunosorbent Assay for 17 α, 20 β-21-trihydroxy-4-pregnen-3-one, a Teleost Gondadal Steroid , 1995 .

[24]  K. Yamauchi,et al.  Changes in Serum Steroid Hormones and Vitellogenin Levels in Cultured Female European Eels Anguilla anguilla during Artificially Induced Ovarian Development , 1994 .

[25]  K. Yamamori,et al.  Induced spawning of the Japanese eel , 1992 .

[26]  F. Tesch.  Changes in swimming depth and direction of silver eels (Anguilla anguilla L.) from the continental shelf to the deep sea , 1989 .

[27]  Y. Zohar,et al.  7 The Gonadal Steroids , 1983 .

[28]  Kelly Selman,et al.  Cellular and dynamic aspects of oocyte growth in teleosts , 1981 .

[29]  K. Yamauchi,et al.  Sexual maturation of Japanese eel and production of eel larvae in the aquarium , 1974, Nature.

[30]  山本 喜一郎,et al.  日本産ウナギ(Anguilla japonica)の卵形成について , 1974 .