Abstract

Nassau grouper (Epinephelus striatus) use the same few spawning aggregati sites each year. The goal of this paper is to map the location of existing and historical Nassau grouper spawning aggregation sites in Belize and the Cayman Islands in relation to reef geomorphology. Observations and data suggest that Nassau grouper spawning aggregations are located near shelf edges and reef promontories so we measured these distances in all cases. A promontory is defined as a distinct turning point, or bend, in the shelf break. The locations of 10 sites in Belize were collected directly in the field while the locations of 5 sites in the Cayman Islands were provided by the Cayman Islands Department of Environment. The geomorphologic reef inventory from the Millennium Reef Mapping Project was used to identify the shelf edge contour in Belize. Bathymetric data in Cayman Islands were collected with an echosounder in order to identify the shelf edges. While Dog Flea Caye in Belize is not distinctive but small mound shape horizontally, the reef structure surrounding all of the other spawning aggregation sites jut into deep water in a convex shape. All spawning aggregation sites in Belize and the Cayman Islands were located within 120 m from the shelf edges and 550 m of turning points in the shelf break. We conclude that though not all spawning aggregations occurred at the exact point of a reef tip, they are located near shelf edges and reef promontories.

PDF Preview