Maturity and spawning pattern of Sardinella aurita in relation to water temperature and zooplankton abundance off Ghana, West Africa
Studies on the maturity and spawning pattern of Sardinella aurita Valenciennes in relation to sea surface temperature (SST) and zooplankton abundance were carried out during the period 1986–91 in Ghanaian waters (West Africa). Both sexes exhibited synchronous seasonal maturation patterns. The mean l...
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Veröffentlicht in: | Journal of applied ichthyology 1999-05, Vol.15 (2), p.63-69 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Studies on the maturity and spawning pattern of Sardinella aurita Valenciennes in relation to sea surface temperature (SST) and zooplankton abundance were carried out during the period 1986–91 in Ghanaian waters (West Africa). Both sexes exhibited synchronous seasonal maturation patterns. The mean length at first maturity occurred at approximately16.7 cm for males and 17.1 cm for females. The mean length at first maturity (L50) increased in comparison with that observed in the 1970s. Three spawning seasons were identified: a major season which extends from July to October, and two minor seasons which occur in March and December. Significant correlations were found between the female gonadosomatic index and SST, between egg abundance and SST, and between egg abundance and zooplankton abundance. The SST seems to be an important factor in species maturation. There is a time lag between attainment of peak gonad maturation and onset of spawning. Spawning appears to commence in response to the start of the coastal upwelling which is characterised by a sharp decrease in SST and an increase in zooplankton abundance. |
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ISSN: | 0175-8659 1439-0426 |
DOI: | 10.1046/j.1439-0426.1999.00111.x |