Exuma Cays Land and Sea Park, Bahamas

Fast Facts

- Compared to fished areas, the reserve had 7 times more biomass of Nassau grouper and 30 times higher density of queen conch.

- Some adult Nassau grouper tagged in the marine reserve moved out into fished areas.

- Very young conch (larvae) produced in the marine reserve appear to be carried outside by ocean currents.

Photos

A Nassau grouper swims over a reef in the Bahamas.
Photo by Chuck Savall

A queen conch on a seagrass bed.
Photo by NOAA

Grouper and Conch Move Into Fished Waters

Scientific studies in the Bahamas suggest that some adult fishes and very young conch produced in a marine reserve swim or drift into fished waters.

The Exuma Cays Land and Sea Park was created in 1959 and was declared a marine reserve in 1985. The reserve comprises more than 400 square kilometers of coral reefs, seagrass beds, mangroves, and sand flats. Scientists have found that some commercially fished species increased in density or biomass inside the marine reserve compared to outside. For example, the marine reserve has 7 times greater biomass of Nassau grouper. Queen conch are up to 30 times more abundant.

Figure: Biomass of Nassau grouper was highest in the marine reserve and decreased with distance from the reserve.

However, the effects are not confined within the marine reserve's borders.

The density of Nassau grouper is highest inside the marine reserve and declines with distance beyond the edge of the reserve. This evidence suggests that abundant adult Nassau grouper in the reserve may swim outside the reserve into fished areas where they may be caught. Indeed, when scientists tagged Nassau grouper in the reserve, some of the fish were later caught up to 220 kilometers away.

Figure: The youngest conch larvae were most abundant in and near the marine reserve.

The marine reserve also appears to be a source of larvae (very young conch) that drift outside and "seed" the surrounding waters. The youngest larvae were most abundant within and nearby the marine reserve, where adult densities are highest, while older larvae were more abundant farther from the reserve. These distribution patterns of larvae with different ages are consistent with ocean current models, which suggest that larvae produced within the reserve would be dispersed outside. Models of ocean currents and larval dispersal may be important tools for determining the most effective locations of marine reserves.

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References

1. Bolden SK (2000) Fishery Bulletin 98:642-645

2. Stoner AW, Ray M (1996) Fishery Bulletin 94:551-565

3. Stoner AW, et al. (1998) Journal of Shellfish Research 17:955-969

4. Sluka R, et al. (1997) Proceedings of the 8th Annual International Coral Reef Symposium 2:1961-1964

5. Lipcius RN, et al. (1997) Marine and Freshwater Research 48:807-815

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