Includes bibliographical references. / A total of 553 male southern African sardine Sardinops sagaxcollected between 2010 and 2012 from around southern Africa, including from the northern Benguela off Namibia and from the South African west, south and east coasts, were examined for the occurrence of a testicular coccidian Eimeria sardinae to assess its potential use as a "biological tag" in order to differentiate between hypothesized discrete sardine stocks within the region. Sardine from Namibia and from the South African east coast showed no infection by E. sardinae, whereas fish from the South African west and south coasts were infected. Average prevalence infection values of 48.9 ± 6.3 and 48.1 ± 9.7% were recorded for sardine from the west and south coasts. Average infection intensity of 49.5 ± 15.8 oocysts per sample was recorded for the west coast and 69.8 ± 33.5 oocysts per sample for the south coat sardine. There was no significance difference in E. sardinae infection (t=0.08; p=0.94) in S. sagax from the South African west coast and south coast. These results provide some support for the hypothesis of multiple sardine stocks off southern Africa and hence are important for fisheries management. The intensity of infection had a significant (Analysis of Variance-NOVA, p<0.05) negative effect on the gonadosomatic index values of infected fish from both the west and south coasts. There was a declining trend in condition factor values with increasing intensity of infection category, however no significant effect was observed. The marked negative effect of infection intensity on GSI, with heavy infection possibly leading to parasitic castration, has potentially important implications for sardine population dynamics and requires futher research.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uct/oai:localhost:11427/9799 |
| Date | January 2013 |
| Creators | Ssempa, Nurudean Norman |
| Contributors | Reed, Cecile C, Van der Lingen, Carl D |
| Publisher | University of Cape Town, Faculty of Science, Department of Biological Sciences |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Master Thesis, Masters, MSc |
| Format | application/pdf |
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