Commercial fishermen know that when these masses of fish flesh come together, there is no better time to snag them for resale. The Little Cayman model including video census data ran from 2005 to 2018 (the range of years during which we captured video census, except 2007, 2011, and 2016, when conditions and fish behavior precluded video capture). At predictable times and locations each year, individuals gather to reproduce. The model for Cayman Brac runs from 2008 to 2018 as both datasets cover this period, although the observations across years were sparser than on Little Cayman (2 y of mark–resight data, 4 y of video census). Understanding the population response of aggregating species to such management actions requires accurate estimates of population size across time. In both A and B, the black dots show the median posterior estimates, and the shaded boxes show the 95% Bayesian CI in years with observations (tag and/or video census counts). Although exceptionally coarse, observational evidence from 2012 and 2018 suggests that the FSA has remained highly depressed (500 or less fish) over the same time frame that Little Cayman and Cayman Brac showed marked growth. Other countries with FSAs of Nassau grouper and other aggregating species should thus expect that management actions aimed at recovering FSA stocks, while ultimately effective, may take decades or longer to meet management targets. Synopsis of Biological Data on the Nassau Grouper, Population structure and phylogeography in Nassau grouper (, The ups and downs of coral reef fishes: The genetic characteristics of a formerly severely overfished but currently recovering Nassau grouper fish spawning aggregation, Larval transport pathways from Cuban spawning aggregattions (Snappers; Lutjanidae) based on biophysical modeling, “Charting a course for nassau grouper recovery in the caribbean: What we’ve learned and what we still need to know”, Proceedings of the 60th Gulf and Caribbean Fisheries Institute. The close-up map shows the historical site on the east end of Little Cayman (circle) and active spawning sites on the west end of Little Cayman and the east end of Cayman Brac (triangles). 60605 Normally solitary and territorial, during the winter full moons grouper travel, sometimes over great distances, and “group” together to spawn. However, there is no doubt that a high level of reserve-boundary fishing observed between 2003 and 2016 contravened any potential population gains. However, the surprisingly high interannual variability in estimates of FSA size on Little Cayman, particularly when considering the mark–resight only model results (Figs. wrote the paper. Behavior: Nassau grouper form large spawning aggregations, making this species highly vulnerable to overharvest. The U.S. National Marine Fisheries Service recently completed a review of the status of the species for Endangered Species listing. For instance, surveyors with more survey experience may detect tags with more accuracy than novices (i.e., they have fewer false-negative detections). For Little Cayman, the results show that the population decreases from around 2,267 fish in 2006 (95% Bayesian CI of 1,910 and 2,636) to 1,256 in 2009 (95% Bayesian CI of 1,043 and 1,484), at which point, it increased steadily through time to reach 7,070 fish in 2018 (95% Bayesian CI, 5,937 and 8,201). The fertilized eggs hatch after ∼24 h (9) and remain as pelagic larvae for 35 to 45 d (21, 22). Now they can follow where individual groupers move throughout the year, including during the long spawning migrations. The spatiotemporal predictability of Nassau grouper FSAs makes them particularly susceptible to overfishing during the spawning season (2). All groupers were reported together for fishery landings data, and specific data on Nassau grouper catch is limited. We carried out all mark–resight and video censuses at Nassau grouper FSAs on the west end of Little Cayman and the east end of Cayman Brac, in the Cayman Islands (Fig. Copyright © 2020 the Author(s). Nearly all studies presenting evidence for FSA overfishing rely on estimates of spawner abundance or catch at FSAs as a proxy for population status. Subsequently, we present results from the integrated population model that contains both mark–resight data and video census data. Conditions at the only known remaining Nassau grouper FSA on Grand Cayman (east end) precluded the research methods we outline below. Nassau grouper reach sexual maturity between 4 to 8 y of age (22), and, as such, the subadult Nassau grouper observed in 2012 should have matured and recruited to the FSA between 2015 and 2018. Funding was provided in part by the Lenfest Ocean Program, the Disney Conservation Fund, National Oceanic and Atmospheric Administration International Coral Reef Conservation Program Grant NA04NOS4630287, P. Hillenbrand, and the J. Edward Mahoney Foundation. For 2018, the size of the Nassau grouper population attending the FSA for Little Cayman Island is estimated to be 5,223 individuals, 95% Bayesian credible interval (CI) of 4,413 and 6,310, an increase from the estimated ∼2,000 fish in 2003. Using an integrated population model that leverages both mark–resight and video census techniques, we demonstrate that Nassau grouper have undergone a remarkable recovery during this time frame. In response, marine resource managers in many locations have established marine protected areas or seasonal closures to recover these overfished stocks. Ingress and settlement in the nassau grouper. Population monitoring of the species at Saint-Martin within the AMP framework has shown that Nassau grouper density is quite low, once at sites outside the reserve. The only other study we are aware of that documents recovery of a Nassau grouper population comes from the US Virgin Islands Grammanik bank, were divers estimated a change in FSA size from ∼30 to ∼100 fish over a 5-y window of time (based on diver observations such as those we present here for Grand Cayman). Changing environmental conditions and genetic adaptations may explain how penguins radiated and expanded their geographic ranges to encompass diverse environments. These issues, in part, led to the development and passage of the legislation establishing complete seasonal closures on the fishery in 2016. The Nassau grouper (Epinephelus striatus) inhabits the waters of the Bahamas and the Caribbean, and averages about 20 pounds in weight. While we were unable to collect the tagging and video census data necessary to include Grand Cayman in our analysis, the management actions taken by the Cayman government encompass all 3 islands. A study, published Jan. 6, has found that the population of Nassau grouper (Epinephelus striatus) around Little Cayman Island more than tripled between 2003 and 2015. Researchers are also describing and assessing spawning aggregations known previously only through anecdotal reports and local knowledge, and gaining an understanding of how grouper populations connect and interact within Bahamian waters. Au recensement de 2010, la population du comté s'élevait à 1 339 532 habitants (1 334 544 en 2000) et sa densité à 1 798,5 hab./km 2. These spawning aggregations, occurring at predictable locations and times—after the full moon in December or January in the Bahamas—have long made this species an easy target for fishermen. Taking account of time, we develop an autoregressive state–space model of Nassau grouper populations on both islands and inform year-specific population estimates using mark–resighting observations. While diving on the aggregation site, surveyors pseudorandomly identified 50 consecutive individuals (where they could clearly and fully see the tagging area on each individual fish) and recorded a mark–resight only when the individual fish was tagged on the side closest to the surveyor. Furthermore, despite having the same level of protection, the population on Cayman Brac appears to have only very recently undergone population expansion. Data from “Data and Code for - Recovery of critically endangered Nassau grouper (Epinephelus striatus) in the Cayman Islands following targeted conservation actions.” Zenodo. performed research; L.W. Which fish populations increased, and which fish populations decreased? We thus modeled the counts of sides of tagged individuals for survey i in year y, ti,y, using a binomial observation model:ti,y∼binomial(py,ni),, where py represents the proportion of sides of fish in the aggregating population that are tagged in year y, and ni represents the number of fish sides counted in survey i. In this study, we conclusively demonstrate that aggressive FSA protections in the Cayman Islands have resulted in the sustained recovery of an endangered reef fish that was previously on the brink of extirpation. Data from “IntegratedStateSpace_tagvideodata.” GitHub. Even with these aggressive management actions, it is clear that population recovery takes considerably longer than time-to-maturity for the species, indicating a multigenerational timeline is necessary for conservation success. This work also has broader international importance for the species because the Bahamas is one of the few countries in the Nassau grouper’s range where populations still support spawning aggregations. The spawning site at Little Cayman is at a shelf break at 30 m, dropping off to >100 m, and the Cayman Brac site is at a gentle slope starting at 40 m, dropping to >100 m. In 2017, the human population of the Cayman Islands was 63,415, with around 200 on Little Cayman and just over 2,000 on Cayman Brac (85). Both models show that the Little Cayman Nassau grouper FSA has dramatically increased since the start of the tagging program in 2008 (Table 2 and Fig. At the time of discovery, the FSA consisted of ∼7,000 fish; in 2 y of fishing, the CI-DoE recorded at least 4,000 Nassau grouper caught (excluding undocumented take that was likely substantial) (8, 20). It is estimated that over one third of the spawning areas have disappeared and the grouper is considered commercially extinct in some areas. Divers collected 4,540 resighting censuses in total, with the vast majority (4,399) from the Little Cayman aggregation site. Data is scarce on historical Nassau grouper numbers. Nassau grouper populations have experienced dramatic declines over the last century due to overfishing on FSAs (2, 17, 33, 34, 39). We thank the many research divers who have participated in and supported the REEF/CI-DoE Grouper Moon Project. Therefore, the observed 2005 to 2008 decline may be attributed to a lack of strong year classes in the previous years. 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. Currently, Nassau grouper are occasionally reported during underwat… Our group saw small gatherings of fish, 4-8 at the most. At up to 4 feet long and 50 pounds, the Nassau grouper (Epinephelus striatus) was historically one of the most important food fishes throughout the Caribbean and West Indies. In the Pacific, researchers used transect methods to document increased abundance of multiple grouper species at a multispecies FSA site 5 y after community-based marine protected-area establishment (84). Working from Shedd's research vessel, the R/V Coral Reef II, our diving biologists moored transmitters to the ocean floor and implanted fish with acoustic tags the size of an AA battery. We show that over the last 15 y the Nassau grouper population on Little Cayman has more than tripled in response to conservation efforts. In Little Cayman, the aggregate population increased from approximately 1,200 individuals in 2009 to more than 7,000 … To evaluate the assumption that the mean proportion of tagged fish remains constant across all surveys collected, we subset the data and compared model results from 1) all survey data, 2) surveys from dives on which more than 10 surveys were completed (i.e., dives where survey conditions were good), and 3) surveys from the day prior to, on, and after peak spawning (i.e., surveys conducted around the night we observed the most spawning). FSAs, particularly for large-bodied grouper and snapper species, tend to occur at locations that are difficult to reach. We also thank the generous support and logistical assistance provided by local Cayman businesses and residents (including, but not limited to, Little Cayman Beach Resort, Southern Cross Club, and Guy Harvey). By separating the process and observation components of our model framework, we afford the flexibility to inform the process model by more than one class of observations, e.g., an integrated population model (49). Here, we provide evidence for the recovery of Little Cayman and Cayman Brac Nassau grouper populations over the last decade, based on data generated from both a mark–resight program and video census techniques (47, 48). In the United States, mortality rates and life expectancy were worse for Blacks during nonpandemic years than for Whites during the COVID-19 pandemic, a study finds. Home Local Nassau grouper population bouncing back Nassau groupers gather in 2018 at a site off the coast of Little Cayman for their annual spawning aggregation. Other potential mechanisms contributing to recruitment-related Allee effects include a breakdown in spawning behavior at small FSAs (10) or a breakdown in the social transmission of FSA locations (e.g., “learning where to spawn”) at low population sizes (10, 29). Regardless of the specific mechanisms leading to the apparent delayed recovery, it is clear that persistent long-term protections have the potential to ultimately foster recovery. In a contemporary context, few of the known remaining FSAs host more than 1,000 individuals (2, 5, 35, 36). This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1917132117/-/DCSupplemental. where, Vm,y is the count made by reviewer m of video from year y; Ny is the spawning population in year y; and σy is the SD in year y. By all indications, despite existing protections in the Bahamas, Nassau grouper populations are declining. Researchers want to mimic animal impulses using chaotic dynamics, eventually in robots. Author contributions: S.A.H., C.V.P.-S., C.M., P.B., B.C.J., and B.X.S. Au niveau mondial le nombre total de cas est de 64 007 836, le nombre de guérisons est de 41 170 820, le nombre de décès est de 1 483 401. We treated yearly population growth, μy, terms as random effects drawn from a normal distribution with a mean μ¯ (the model-estimated overall population mean growth rate in log space), and SD σproc (process error). The Cayman Island government has taken a multifaceted management approach by enacting a closed season, creating year-round FSA site closures, and implementing gear restrictions, slot limits, and bag limits during the open season. In all years, we concentrated tagging efforts over multiple days (usually 2 to 3) early in the spawning period. Image credit: Aurora Fernández Durán (photographer). Because of the implementation of these deliberate, science-based conservation strategies, Little Cayman is now home to the largest remaining identified Nassau grouper aggregation anywhere in the world. Multiple lines of evidence support this assumption. See online for related content such as Commentaries. and B.X.S. Evaluation of a conservation strategy: A spawning aggregation closure for red hind, Conservation and fisheries effects of spawning aggregation marine protected areas: What we know, where we should go, and what we need to get there, Historical and contemporary evidence of a mutton snapper (, Historical analysis of Cuban commercial fishing effort and the effects of management interventions on important reef fishes from 1960–2005, Trends in commercial fishery landings of groupers and snappers in Bermuda from 1975 to 1992 and associated fishery management issues, Biology, Fisheries and Culture of Tropical Groupers and Snappers, ICLARM Conf. While the Little Cayman Nassau grouper aggregation is arguably one of the most accessible in the Caribbean, it exists on an exposed shelf break, requires a 30-min boat transit to the site, and can only be surveyed in good conditions by research divers with the skills and certification to regularly conduct 30-m dives. Below, we present findings from the mark–resight model on Little Cayman and Cayman Brac without the video census data included. The Grouper Moon Project aims to provide the Cayman Islands government with monitoring data necessary to effectively assess and manage Nassau grouper populations. This timing coincides with the large population increases in the latter 3 y of this study (Fig. Conditions at Grand Cayman’s aggregation site preclude sustained research diving activities. Taken together, these findings strongly support the assumption that changes in the size of an FSA are a proxy for changes in the regional stock of spawners. By utilizing a dual camera system, they have turned the BRUVS into stereo-video systems that enable them to measure the length of the fish, which can be used as a proxy for age. Pull on a pair of tall rubber boots and experience what it’s like to be a marine mammal trainer! 2). These early efforts at monitoring fishing were abandoned by the late 1990s as catch across all 3 Cayman Islands had completely collapsed. These findings demonstrate that spatial and seasonal closures aimed at rebuilding aggregation-based fisheries can foster conservation success. That is, the change in the abundance or catch of spawners at the FSA is assumed to correlate with a change in stock status (2, 14, 54, 64, 65). They are using acoustic telemetry, a technology that uses sound pulses—pings—to track individual fish’s movements. 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