Spawning Agregation (SPAG) Monitoring

Many large-bodied grouper and snapper species, including the critically endangered Nassau grouper (Epinephelus striatus) engage in a behavior known as aggregation spawning. This describes a phenomenon wherein sexually mature individuals gather in large numbers to reproduce in response to a medley of environmental and physiological cues. These aggregations are highly predictable, often happening at the same location each year. This predictable gathering of fish makes an attractive target to fishermen, who have historically exploited these spawning aggregations. Unfortunately, this has led to massive depletions in the populations of many spawning species.

In the 1970s, approximately 15,000 Nassau groupers aggregated at Northeast Point, Glover's Reef Atoll for a mass spawning event. However, in 1999, WCS researcher Dr. Enric Sala and his team estimated that this number had fallen to 3,000. Research at known spawning sites across the country found that the spawning group at many sites had fallen below 1000 fish, or even disappeared entirely in a local extirpation of the species.

As a result of these findings, the Government of Belize passed legislation to fully protect 11 Nassau grouper spawning sites, including Northeast Point, and introduced a four-month closed season. Since the passing of these protective regulations, WCS and reserve staff have been conducting counts of Nassau groupers at the spawning aggregation site at Northeast Point for more than a decade, using the protocol developed for the Mesoamerican Reef region. This protocol was updated in 2011 with the assistance of Dr. Yvonne Sadovy of the Society for the Conservation of Reef Fish Aggregations (SCRFA). Further protection measures for the species were introduced in 2009, including a minimum and maximum size limit and the protection of two more aggregation sites.

Today, the Nassau groupers at Northeast Point number less than 1,000. WCS continues to work with the Belize National Spawning Aggregation Working Group to monitor and promote measures that will lead to recovery of the species. The Spawning Aggregation Working Group is comprised of representatives from the Belize Fisheries Department, the Coastal Zone Management Authority and Institute, and a cadre of NGOs, with a mission statement to provide decision-makers with the most current information regarding the status of Belize's Fish Spawning Aggregations through data and knowledge sharing.