Age structure of annual Nothobranchius fishes in Mozambique: is there a hatching synchrony?
Article first published online: 19 JAN 2011
© 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles
Journal of Fish Biology
Volume 78, Issue 3, pages 796–809, March 2011
How to Cite
Polačik, M., Donner, M. T. and Reichard, M. (2011), Age structure of annual Nothobranchius fishes in Mozambique: is there a hatching synchrony?. Journal of Fish Biology, 78: 796–809. doi: 10.1111/j.1095-8649.2010.02893.x
- Issue published online: 2 MAR 2011
- Article first published online: 19 JAN 2011
- (Received 22 September 2010, Accepted 24 November 2010)
- age validation;
- south-east Africa;
- temporary pools
The age structures of populations of African annual Nothobranchius spp. were examined for the first time. Daily increments in sagittal otoliths of Nothobranchius furzeri, Nothobranchius kadleci, Nothobranchius orthonotus and Nothobranchius rachovii from southern and central Mozambique were used for age determination. Four hypotheses were tested: (1) timing of hatching is consistent with the calendar onset of the rainy season, (2) hatching is synchronized within a population in a pool, (3) there is a difference in hatching date between geographical regions differing in mean total annual precipitation and (4) sympatric Nothobranchius spp. hatch at the same time. The results show that daily increment analysis represents an applicable method for age determination in Nothobranchius spp. Despite a significant positive relationship between age and size of fishes, a pronounced variation in fish size at an age precluded the use of fish size as a valid age marker. Timing of hatching was not consistent with the calendar onset of the rainy season. Interpopulation variability was observed in the degree of hatching date synchronization within a population. Hatching dates were relatively uniform in some populations, while there was considerable variability in others. Differences in timing of hatching date were found in only 1 of 2 years within the three regions investigated (Chefu, lower Limpopo and Sofala regions), each of which differed in mean total annual rainfall. The hatching dates of sympatric Nothobranchius spp. were marginally different, but further testing on a larger sample is needed for conclusive results.