Marine Protected Areas (MPAs) as a Fisheries Management Tool for the Nassau Grouper (Epinephelus striatus) in Belize

The Nassau grouper, Epinephelus striatus, was once an important commercial fish species in the Caribbean, but is now considered commercially extinct throughout its range. Protection measures have included protection of adults via seasonal closures and spawning aggregation site reserves (SASRs). Marine protected areas (MPAs) are a promising fisheries management tool being used increasingly worldwide but are not specifically directed at the conservation of Nassau grouper. This thesis uses Belize as a case study location to determine how the established MPA network may contribute towards its protection. It was found that the Belize MPA network as a system may not contribute greatly, however, on an individual basis some MPAs contribute more to protection than others. Those MPAs which have characteristics most suitable for this species are Gladden Spit and Silk Cayes, Sapodilla Cayes, Bacalar Chico, Glovers Reef, Hol Chan, and South Water Caye Marine Reserves.

Marine Protected Areas (MPAs) as a Fisheries Management Tool for the Nassau Grouper (Epinephelus striatus) in Belize

The Nassau grouper, Epinephelus striatus, was once an important commercial fish species in the Caribbean, but is now considered commercially extinct throughout its range. Protection measures have included protection of adults via seasonal closures and spawning aggregation site reserves (SASRs). Marine protected areas (MPAs) are a promising fisheries management tool being used increasingly worldwide but are not specifically directed at the conservation of Nassau grouper. This thesis uses Belize as a case study location to determine how the established MPA network may contribute towards its protection. It was found that the Belize MPA network as a system may not contribute greatly, however, on an individual basis some MPAs contribute more to protection than others. Those MPAs which have characteristics most suitable for this species are Gladden Spit and Silk Cayes, Sapodilla Cayes, Bacalar Chico, Glovers Reef, Hol Chan, and South Water Caye Marine Reserves.

Spatial ecology of Nassau Grouper at home reef sites: using acoustic telemetry to track a large, long-lived epinephelid across multiple years (2005-2008)

Characterizing the behavior of coral reef fishes at home reef sites can provide insight into the mechanisms of spatial ecology and provide a framework for spatial resource management. In the Caribbean, populations of Nassau grouper Epinephelus striatus have declined due to fishing impacts on spawning aggregations. Despite local and regional efforts by fisheries managers to implement regulations protecting spawning aggregations, few Nassau grouper populations appear to be recovering. In order to improve management strategies for this critically endangered species, it is necessary to understand the spatial ecology of the species across seasons and years. In the Cayman Islands, we used a multi-year, presence/absence, depth-coded acoustic tagging dataset of Nassau grouper to characterize patterns in the species’ behavior and vertical habitat use at home reef sites. Twenty acoustically tagged individuals (56-84 cm, 70.01 ± 7.40 cm; total length, mean ± SD) maintained consistent home reef sites, although some fish regularly shifted activity centers within the home site, often following a seasonal spawning migration. Seven fish with depth-coded tags showed a higher probability of vertical movement in the hours immediately following dawn and preceding dusk. We found evidence of a positive relationship between the fish condition factor and depth of home reef site. The finding of persistent home reef sites across years suggests that properly sized spatial reserves at home reef sites can be a useful complement to spawning aggregation protection when considering management strategies for Nassau grouper.

Recovery of critically endangered Nassau grouper (Epinephelus striatus) in the Cayman Islands following targeted conservation actions

Many large-bodied marine fishes that form spawning aggregations, such as the Nassau grouper (Epinephelus striatus), have suffered regional overfishing due to exploitation during spawning. In response, marine resource managers in many locations have established marine protected areas or seasonal closures to recover these overfished stocks. The challenge in assessing management effectiveness lies largely in the development of accurate estimates to track stock size through time. For the past 15 y, the Cayman Islands government has taken a series of management actions aimed at recovering collapsed stocks of Nassau grouper. Importantly, the government also partnered with academic and nonprofit organizations to establish a research and monitoring program (Grouper Moon) aimed at documenting the impacts of conservation action. Here, we develop an integrated population model of 2 Cayman Nassau grouper stocks based on both diver-collected mark–resight observations and video censuses. Using both data types across multiple years, we fit parameters for a state–space model for population growth. We show that over the last 15 y the Nassau grouper population on Little Cayman has more than tripled in response to conservation efforts. Census data from Cayman Brac, while more sparse, show a similar pattern. These findings demonstrate that spatial and seasonal closures aimed at rebuilding aggregation-based fisheries can foster conservation success.