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

Abstract

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 aggregationbased fisheries can foster conservation success.fish-spawning aggregation | Nassau grouper | integrated population model | mark-resight | tagging

RAD-Seq Analysis and in situ Monitoring of Nassau Grouper Reveal Fine-Scale Population Structure and Origins of Aggregating Fish

“…Round-trip migration distances covered by Nassau grouper in The Bahamas can exceed 300 km , thus surpassing distances reported for fish in the Cayman Islands and Belize (e.g., Whaylen et al, 2004;Semmens et al, 2007;Starr et al, 2007). The migratory patterns displayed by Nassau grouper in this study are congruent with previous research in The Bahamas in terms of routes and distances 1 https://www.seatemperature.org/central-america/bahamas/nassau.htm (∼15.7-176 km) traveled (Bolden, 2000;Stump et al, 2017).…”

A Decade of Monitoring an Indo-Pacific Grouper Spawning Aggregation: Benefits of Protection and Importance of Survey Design

“…Other aggregating groupers are also threatened, including goliath grouper, Epinephelus itajara, and gag grouper, Mycteroperca microlepis (Coleman et al, 1996;Koenig et al, 2018;Bertoncini et al, 2018), at least partly due to fishing on their aggregations (Sadovy de Mitcheson and Colin, 2012). On the other hand, examples of recovery following successful protection, while few, are growing (Nemeth, 2005;Hamilton et al, 2011;Waterhouse et al, 2020).…”

Life below water: Fish spawning aggregations as bright spots for a sustainable ocean

“…Long-term monitoring at locations where fishing communities have effectively removed or reduced fishing pressure on FSAs has shown that depleted FSAs can recover populations restoring ecosystem integrity and the flow of ecosystem goods and services (Aburto-Oropeza et al 2011;Chollett et al 2020;Hamilton et al, 2011;Kobara et al, 2013;Nemeth, 2005) (Figure 1). For example, a fisher-scientist-manager partnership in the Cayman Islands monitoring FSAs for 15 years found that Nassau grouper populations had tripled in response to conservation efforts (Waterhouse et al, 2020). In the U.S. Caribbean, average density and biomass of spawning red hind (E. guttatus) increased by over 60% within 5years of a permanent fishery closure (44 km 2 ) implemented through a partnership between fishers, local scientists and fishery managers (Nemeth, 2005).…”