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Sexual dimorphism and natural movements of the American eel(Anguilla rostrata) in Rhode Island streams and estuaries

  • H. E. Winn
  • W. A. Richkus
  • L. K. Winn
Article

Summary

1. The eyes of silver males were much enlarged, but not thoses of femaleAnguilla rostrata specimens.

2. Silver males were smaller than silver females.

3. Males predominated in freshwater and the proportion of females increased in estuaries.

4. In trap catches from 1969 to 1972, most silver eel runs occurred from September through November and came after rains or in the third and fourth lunar quarters. More yellow eels are also caught at this time.

5. Based on records from an electronic fish counter, silver eels moved primarily from just after sundown to 2300 hr.

6. It is suggested that with regard to stimuli initiating migration, a great deal of redundancy is built into the system so that reproduction is assured.

Keywords

Migration Waste Water Water Pollution Sexual Dimorphism Natural Movement 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Geschlechtsdemorphismus und Wanderaktivität des Amerikanischen Aales(Anguilla rostrata) in Fließgewässern und Flußmündungen von Rhode Island

Kurzfassung

Der Augendurchmesser männlicher Amerikanischer Blankaale(Anguilla rostrata) war beträchtlich größer als derjenige von Amerikanischen Gelbaalen. Blankaalmännchen hatten eine wesentlich geringere Durchschnittslänge als Blankaalweibchen. In kleinen Fließgewässern dominierten die Männchen, in Flußmündungen war der Weibchenanteil vergleichsweise größer. Die Abwanderung ins Meer fand hauptsächlich während der Monate September bis November statt und war verstärkt bei nennenswerten Regenfällen sowie während des dritten und vierten Mondviertels. Die Untersuchungen erbrachten in vieler Hinsicht ähnliche Ergebnisse, wie sie vom Europäischen Aal bekannt sind. Es wird angenommen, daß hinsichtlich der Stimuli für Beginn und Aufrechterhaltung der Laichwanderung eine große Zahl von funktionellen Sicherungen vorhanden ist, welche die Vermehrung gewährleisten.

Literature cited

  1. Bertin, L., 1956. Eels. Cleaver-Hume, London, 192 pp.Google Scholar
  2. Bigelow, H. B. &Welsh, W. W., 1925. Fishes of the Gulf of Maine. Bull. U.S. Bur. Fish.40 (1), 1–567.Google Scholar
  3. Boetius, I. &Boëtius, J., 1967. Studies in the European eel,Anguilla anguilla (L.). Experimental induction of the male sexual cycle, its relation to temperature and other factors. Meddr. Danm. Fisk. -og Havunders.4, 339–405.Google Scholar
  4. Boëtius, J., 1967. Experimental indication of lunar activity in European silver eels,Anguilla anguilla (L.). Meddr. Danm. Fisk. -og Havunders.6, 1–6.Google Scholar
  5. —— &Møller-Christensen, E., 1962. Studies of ovarial growth induced by hormone injections in the European and American eel (Anguilla anguilla L. andAnguilla rostrata LeSueur). Meddr. Danm. Fisk. -og Havunders.3, 183–198.Google Scholar
  6. Bräutigam, R., 1961. Über Versuche zur Intensivierung des Blankaalfanges durch die Kombination von Lichtsperren und Großreusen und ihre grundsätzlichen Bedingungen. Fisch.-Forsch.4, 19–25.Google Scholar
  7. Carlisle, D. B. &Denton, E. J., 1959. On the metamorphosis of the visual pigments ofAnguilla anguilla (L.). J. mar. biol. Ass. U.K.38, 97–102.Google Scholar
  8. Deelder, C. L., 1954. Factors affecting the migration of the silver eel in Dutch inland waters. J. Cons. perm. int. Explor. Mer.20, 177–185.Google Scholar
  9. -- 1970. Synopsis of biological data on the eelAnguilla anguilla (Linnaeus) 1758. F.A.O. Fish. Synopses80.Google Scholar
  10. Eales, J. G., 1968. The eel fisheries of Eastern Canada. Bull. Fish. Res. Bd Can.166, 1–79.Google Scholar
  11. Frost, W. E., 1950. The eel fisheries of the River Bann, Northern Ireland, and observations on the age of silver eels. J. Cons. perm. int. Explor. Mer16, 358–383.Google Scholar
  12. Hildebrand, S. F. &Schroeder, W. C., 1928. Fishes of Chesapeake Bay. Bull. U.S. Bur. Fish.43 (1), 1–366.Google Scholar
  13. Jens, G., 1952–53. Über den lunaren Rhythmus der Blankaalwanderung. Arch. FischWiss.4, 94–110.Google Scholar
  14. Knöpp, Von H., 1952. Die Laichwanderung des Aales(Anguilla vulgaris) und ihre Beziehungen zu Mondstand und Wetter. Zool. Anz.149, 169–177.Google Scholar
  15. Lowe, R. H., 1952. The influence of light and other factors on the seaward migration of the silver eel (Anguilla anguilla L.). J. Anim. Ecol.21, 275–309.Google Scholar
  16. Rasmussen, C. J., 1951. Two Danish finds of female eels (Anguilla anguilla) in spawning or partial spawning dress. Rep. Dan. biol. Stn53, 36–39.Google Scholar
  17. Richkus, W. A., 1974. The influence of environmental variables on the migratory behavior of adult and juvenile alewives,Alosa pseudoharengus (Wilson). Thesis, Univ. Rhode Island, 225 pp.Google Scholar
  18. —— 1975. Factors influencing the seasonal and daily patterns of alewives(Alosa pseudoharengus) migration in a Rhode Island river. J. Fish. Res. Bd Can.31, 1485–1497.Google Scholar
  19. Smith, M. W. &Saunders, J. W., 1955. The American eel in certain fresh waters of the Maritime Provinces of Canada. J. Fish. Res. Bd Can.12, 238–269.Google Scholar
  20. Svardson, G., 1949. Eels(Anguilla anguilla) found in Sweden in partial nuptial dress. Rep. Inst. Freshwat. Res. Drottningholm29, 129–134.Google Scholar
  21. Tesch, F.-W., 1973. Der Aal. Parey, Berlin, 306 pp.Google Scholar
  22. Vladykov, V. D., 1966. Renmarks on the American eel (Anguilla rostrata,LeSueur). Sizes of elvers entering streams; the relative abundance of adult males and females; and present economic importance of eels in North America. Verh. int. Ver. theor. angew. Limnol.16, 1007–1017.Google Scholar
  23. —— 1973. Macrophthalmia in the American eel(Anguilla rostrata). J. Fish. Res. Bd Can.30, 689–693.Google Scholar
  24. Wenner, C. A. &Musick, J. A., 1974. Fecundity and gonad observations of the American eel,Anguilla rostrata, migrating from Chesapeake Bay, Virginia. J. Fish. Res. Bd Can.31, 1387–1391.Google Scholar
  25. Winn, H. E. &Hammen, S., 1969. Migratory habits of the American eel pose problems for biologists. Maritimes43, 3–5.Google Scholar

Copyright information

© Biologischen Anstalt Helgoland 1975

Authors and Affiliations

  • H. E. Winn
    • 1
  • W. A. Richkus
    • 1
  • L. K. Winn
    • 1
  1. 1.Graduate School of OceanographyUniversity of Rhode IslandKingstonUSA

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