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| Öhman, M.C.; Isidore, M.; Payet, R.J.; Robinson, J.; Marguerite, M.A.. |
| Many coral reef fish species aggregate at specific times and locations for the purpose of spawning. This study examined the spatial and temporal distribution of spawning aggregations in the Seychelles. An interview-based survey of the principal stakeholders, mainly artisanal fishers, yielded 89 reports of aggregation fishing for 26 demersal and semi-pelagic fish species. Grouper aggregations were largely concentrated in the outer coralline islands of the exclusive economic zone, whilst those of snappers and rabbitfishes were mainly reported from locations on the Seychelles Bank. The spatial patterns among fish families were attributed to a combination of differences in species abundance and distribution as well as variation in fishing effort. Spawning... |
| Tipo: Journal Contribution |
Palavras-chave: Coral reefs; Reef fish; Spawning. |
| Ano: 2004 |
URL: http://hdl.handle.net/1834/1142 |
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| Öhman, M.C.; Kuguru, B.L.; Muhando, C.A.; Wagner, G.M.; Mbije, N.E.. |
| This study examined the distribution and abundance of corallimorpharians (Cnidaria, Anthozoa) in Tanzania in relation to different aspects of the coral reef environment. Five reefs under varying degrees of human disturbance were investigated using the line intercepttransect and point technique. Corallimorpharian growth and the composition of the substratum were quantified in different habitats within reefs: the inner and middle reef flat, the reef crest, and at the 2and 4 m depths on the reef slope. Corallimorpharians occurred on all the reefs and 5 species were identified: Rhodactis rhodostoma, R. mussoides, Ricordea yuma, Actinodiscus unguja and A. nummiforme. R. rhodostoma was the dominant corallimorpharian at all sites. Within reefs, they had the... |
| Tipo: Journal Contribution |
Palavras-chave: Coral reefs. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/728 |
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| Jiddawi, N.S.; Öhman, M.C.. |
| Fishery resources are a vital source of food and make valuableeconomic contributions to the local communities involved in fisheryactivities along the 850 km stretch of the Tanzania coastline andnumerous islands. Small-scale artisanal fishery accounts for themajority of fish catch produced by more than 43000 fishermen in thecountry, mainly operating in shallow waters within the continental shelf,using traditional fishing vessels including small boats, dhows, canoes,outrigger canoes and dinghys. Various fishing techniques are appliedusing uncomplicated passive fishing gears such as basket traps, fencetraps, nets as well as different hook and line techniques. Species com-position and size of the fish varies with gear type and location. Morethan 500 species of... |
| Tipo: Journal Contribution |
Palavras-chave: Marine fisheries. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/754 |
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| Öhman, M.C.; Lindahl, U.; Schelten, C.K.. |
| In 1998, coral reefs of Tanzania were severely affected by bleaching. The coral mortality that followed caused a concern for coral reef degradation and overall resource depletion. In this study, we investigated coral bleaching effects on the coral reef fauna at Tutia Reef in Mafia Island Marine Park, Tanzania. Corals from adjacent reef patches of the species Acropora formosa were transplanted into plots, and reef structure and associated fish assemblages were examined before and after the bleaching event. Following the coral bleaching, 88% of all corals died. A year after the event, a large proportion of the dead corals was still standing. As surviving and dead corals were from different clones, results suggested that genetic variation might influence... |
| Tipo: Report |
Palavras-chave: Coral reefs; Aquatic fauna. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/491 |
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