Effects of size, culling and social history on growth of cultured elvers, Anguilla anguilla (L.)
The growth of newly‐caught elvers was measured after they were separated into four size categories and induced to feed. All sizes grew equally well, indicating that size differences at capture reflected migration history rather than the presence of genetically poor or good growers. Socially experien...
| Published in: | Journal of Fish Biology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1987
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| Online Access: | http://dx.doi.org/10.1111/j.1095-8649.1987.tb05215.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1987.tb05215.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1987.tb05215.x |
| Summary: | The growth of newly‐caught elvers was measured after they were separated into four size categories and induced to feed. All sizes grew equally well, indicating that size differences at capture reflected migration history rather than the presence of genetically poor or good growers. Socially experienced groups of elvers of equivalent size grew, on average, less well due to the presence of socially suppressed fish and fish that did not respond so well to handling or a new social environment. Replicate groups of rapidly‐growing elvers were culled at either 2‐ or 4‐weekly intervals. The large animals removed were replaced by animals of modal size and the growth of selected residual size groups was compared to unculled control groups. Culling tended to increase the instantaneous growth coefficient of remaining small elvers but the added elvers of modal size may have exerted a disproportionate influence on mean growth rates. The effect of large elvers on the growth of small elvers (and vice versa) was monitored using fish labelled subcutaneously with acrylic paint. Separate populations of elvers of each size group were used as controls. After 82 days in mixed populations, about 36% of the original large fish had been’ overtaken’ by small category fish. The results suggested that, following disturbance, the expression of growth in elvers was not necessarily related to size or previous hierarchical position but may be governed by behavioural or physiological responses to handling and changed social environments. |
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