Seychelles' marine protected areas: comparative structure and status of reef fish communities

Published source details Jennings S., Marshall S.S. & Polunin N.V.C. (1996) Seychelles' marine protected areas: comparative structure and status of reef fish communities. Biological Conservation, 75, 201-20.
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Summary

In the Seychelles effective conservation management of reefs is essential due to the demands of fishing and tourism. Marine protected areas (MPAs) play a key role in management strategy of the archipelago but there is little quantitatively-based evidence of the benefits they provide. To help redress this, a study investigated fish assemblages on reefs with different levels of conservation protection.

The four MPAs (designation year; MPA area) and enforcement effectiveness were:

Cousin Island Nature Reserve (1968; 1.2 km²), enforcement effective;

Sainte Anne Marine National Park (1973; 10 km²), enforcement effective;

Baie Ternay Marine National Park (1979; 0.8 km²), enforcement negligible;

Curieuse Marine National Park (1979; 10.8 km²), enforcement by day only;

Regulations at each state that reefs must not be damaged and that fish must not be caught.

Fishes from 16 families were censused on coral reef and granitic reef (corals growing on rock). Sixteen randomly positioned point counts of 7 m radius were made at depths of 3-13 m. Size (length to the nearest 1 cm) and number of census-family species estimated to be more than 7 cm length, were recorded. Fish over 8 cm were censused in a 2 m radius.

Biomass (estimated from census data) and fish species richness was compared on these reef habitats with different levels of protection from fishing and other human activities.

A total of 115 fish species were recorded. Species richness and total biomass, and species richness and biomass of many families were higher on both coral and granitic reefs in the two MPAs with effectively enforced protection.

Biomass was lower at Baie Ternay coralline and Curieuse granitic sites (less effective protection). Total fish biomass at the coralline sites was: Cousin 49.9 (± 3.73 SE) g/m² at; Sainte Anne 68.7 (± 6.34) g/m²; and Baie Ternay 30.2 (± 2.46) g/m² (i.e. 40% lower than at Cousin and 60% lower than at Sainte Anne).

Serranidae (groupers/sea bass) and lutjanidae (snappers) biomass (two families containing many primary fishery target species) was highest at the Cousin coralline site. Lethrinidae (emperors) biomass (another family with many fishery species) was significantly higher at Cousin and Sainte Anne coralline sites. Of granitic sites, Lethrinid and lutjanid biomass was significantly higher at Cousin.

Whilst illegal fishing (and some minor fishing concessions) did not affect fish community characteristics important to most tourist s (abundance and species richness), they had a statistically significant effect on fish community structure in terms of some families containing primary fishery target species.

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