, Volume 243, Issue 1, pp 269–276

Ecological release in feeding behaviour: the case of bluegills in Japan

  • M. Azuma
Fish and Fisheries

DOI: 10.1007/BF00007042

Cite this article as:
Azuma, M. Hydrobiologia (1992) 243: 269. doi:10.1007/BF00007042


The stomach contents were analyzed monthly for each year-class to elucidate the foraging pattern of bluegills in a small vegetated lake by the frequency occurrence and the ‘points’ methods. Seasonal dietary changes of the year-classes were considered comparing the monthly fluctuations in abundance of major prey organisms. Though these bluegills are dietary generalists and opportunists like those in North America, their foraging pattern was characterized by a relatively clearer dietary shift during ontogeny and a wider food niche including piscivorous than those of bluegills with congeners in their home land. Therefore this finding provides evidence of the ecological release caused by the absence of congeners.

Key words

dietary shifts congener-free conditions habitat use piscivorous ‘points’ method community disturbance 

Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • M. Azuma
    • 1
  1. 1.Biological Laboratory, Faculty of EducationNagasaki UniversityNagasakiJapan

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