News about the reproductive ecology of the southern conger eel Conger orbignianus

Congrids inhabit the warm and temperate seas of the world, from the coastline to the slope of various continents. Many of its species are much valued by commercial and artisan fishing; nevertheless, at world level, there is great ignorance about the life cycle of the members of this genus. Some species of the genus, such as those from the North Atlantic, appear to be semelparous, for they cease feeding, decalcify, loose their teeth and migrate to deep waters to spawn. Specimens of the southern conger eel Conger orbignianus were examined for the purpose of learning about their biology in waters of the western South Atlantic. Histological sections were analysed from ovaries of coastal conger specimens from the North Argentina coastal littoral, the Argentine Sea deep waters, and the giant congers from southern Brazil. Two oocitary generations have been observed in coastal females typical of total spawners, with a previtellogenetic batch that does not reach maturity, and a vitellogenetic batch that does it together with its size, completely surrounded by adipose tissue. The ovaries of fish captured in deep waters occupied the whole abdominal cavity, with scarce adipose tissue and degraded body. The giant congers from southern Brazil were captured in very deep waters, healthy, with few atretic oocytes and abundant adipose tissue. Evidence of semelparity was found in the southern conger eel; the asistosis stage, the body degradation during the reproductive migration and gigantism might be common attributes in other species of the genus.

[1]  K. Tsukamoto,et al.  Genetic identification of Conger myriaster leptocephali in East China Sea , 2007, Fisheries Science.

[2]  M. M. Mincarone,et al.  NOTA CIENTÍFICA FIRST RECORD OF THE GREY CONGER Conger esculentus POEY, 1861 (CONGRIDAE) IN BRAZILIAN WATERS , 2005 .

[3]  J. McCleave,et al.  Spawning ofConger oceanicus andConger triporiceps (Congridae) in the Sargasso Sea and subsequent distribution of leptocephali , 1994, Environmental Biology of Fishes.

[4]  K. Able,et al.  Aspects of Metamorphosis and Habitat Use in the Conger Eel, Conger oceanicus , 2003, Copeia.

[5]  A. Akazawa,et al.  Oogenesis in the common Japanese conger Conger myriaster , 2003 .

[6]  C. Antunes,et al.  Aspects of the early life history of the European conger eel (Congerconger) inferred from the otolith microstructure of metamorphic larvae , 2002 .

[7]  G. Menezes,et al.  Diets of forkbeard (Phycis phycis) and conger eel (Conger conger) off the Azores during spring of 1996 and 1997 , 1999 .

[8]  L. Flshelson Comparative internal morphology of deep‐sea eels, with particular emphasis on gonads and gut structure , 1994 .

[9]  C. Grimes,et al.  Biology of the conger eel Conger oceanicus in the Mid-Atlantic Bight , 1988 .

[10]  C. Grimes,et al.  Biology of the conger eel Conger oceanicus in the Mid-Atlantic Bight , 1988 .

[11]  A. Cau,et al.  Relationship of feeding, reproductive cycle and bathymetric distribution in Conger conger , 1984 .

[12]  T. Monod Le complexe urophore des poissons téléostéens , 1968 .

[13]  F. A. Putt,et al.  Animal Tissue Techniques , 1967, The Yale Journal of Biology and Medicine.

[14]  J. Dymond,et al.  Fishes of the western North Atlantic. , 1963 .

[15]  H. Asano Studies on the congrid eels of Japan , 1961 .

[16]  R. H. Kanazawa A revision of the eels of the genus Conger with descriptions of four new species , 1958 .

[17]  H. Bigelow Fishes of the Gulf of Maine , 1925 .

[18]  J. T. Cunningham On the Reproduction and Development of the Conger , 1891, Journal of the Marine Biological Association of the United Kingdom.