An Analysis of Fish Survey Data Generated by Nonexpert Volunteers in the Flower Garden Banks National Marine Sanctuary

Using nonexpert volunteers in monitoring programs increases the data available for use in resource management. Both scientists and resource managers have expressed concerns about the value and accuracy of nonexpert data. We examined the quality of fish census data generated by Reef Environmental Education Foundation (REEF) volunteers of varying experience levels (non experts) and compared these data to data generated by experts. Analyses were done using data from three REEF field survey cruises conducted in the Flower Garden Banks National Marine Sanctuary. Species composition and structure were comparable between the skill levels. Nonexpert data sets were similar to expert data sets, although expert data were more statistically powerful when the amount of data collected was equivalent between skill levels. The amount of REEF survey experience was positively correlated with the power of the data collected. The statistical power of abundance estimates varied between species. These results provide support for the use of nonexpert data by resource managers and scientists to supplement and enhance monitoring programs

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

Migratory behavior of aggregating male Tiger Grouper (Mycteroperca tigris) in Little Cayman, Cayman Islands

Tiger Grouper (Mycteroperca tigris) form fish spawning aggregations (FSAs) around the winter full moons (typically January through April) in the Caribbean. Males defend territories to attract mates in a lek-like reproductive strategy. Prior studies have documented rapid declines in populations with FSA-associated fisheries. This study examines the migratory behavior of adult male Tiger Grouper in Little Cayman, Cayman Islands, to better understand the impacts of aggregation fishing. As part of the Grouper Moon Project, we acoustically tagged ten spawning male Tiger Grouper at the western end of Little Cayman in February 2015. Using a hydrophone array surrounding the island, we tracked the movements of the tagged fish for 13 months. We observed 3 migratory strategies: resident fish (n = 2) that live at the FSA site, neighboring fish (n = 5) that live within 4 km of the site, and commuter fish (n = 3) that travel over 4 km for spawning. Fish began aggregating 2 days before the full moon and left 10–12 days after the full moon, from January to May. Regardless of migratory strategy, all tagged fish that aggregated after February 2015 returned to the west end FSA. However, in January 2016, one fish appeared to attend a different FSA closer to its presumed home territory. Tiger Grouper may establish multiple FSAs around Little Cayman, and males appear to attend FSAs near their home territories. Protracted spawning seasons, FSA site infidelity, and putative FSA catchments should all be considered to ensure sustainable fisheries management for this important species.publishedVersio

Protected fish spawning aggregations as self-replenishing reservoirs for regional recovery

Dispersal of eggs and larvae from spawning sites is critical to the population dynamics and conservation of marine fishes. For overfished species like critically endangered Nassau grouper (Epinephelus striatus), recovery depends on the fate of eggs spawned at the few remaining aggregation sites. Biophysical models can predict larval dispersal, yet these rely on assumed values of key parameters, such as diffusion and mortality rates, which have historically been difficult or impossible to estimate. We used in situ imaging to record three-dimensional positions of individual eggs and larvae in proximity to oceanographic drifters released into egg plumes from the largest known Nassau grouper spawning aggregation. We then estimated a diffusion–mortality model and applied it to previous years' drifter tracks to evaluate the possibility of retention versus export to nearby sites within 5 days of spawning. Results indicate that larvae were retained locally in 2011 and 2017, with 2011 recruitment being a substantial driver of population recovery on Little Cayman. Export to a nearby island with a depleted population occurred in 2016. After two decades of protection, the population appears to be self-replenishing but also capable of seeding recruitment in the region, supporting calls to incorporate spawning aggregation protections into fisheries management.publishedVersio

Patterns of color phase indicate spawn timing at a Nassau grouper Epinephelus striatus spawning aggregation

Nassau grouper Epinephelus striatus are a large bodied, top level predator that is ecologically important throughout the Caribbean. Although typically solitary, Nassau grouper form large annual spawning aggregations at predictable times in specific locations. In 2003, The Cayman Islands Marine Conservation Board established protection for a newly rediscovered Nassau grouper spawning aggregation on Little Cayman, British West Indies. The large size of this aggregation provides a unique opportunity to study the behavior of Nassau grouper on a relatively intact spawning aggregation. During non-spawning periods Nassau grouper display a reddish-brown-and-white barred coloration. However, while aggregating they exhibit three additional color phases: “bicolor”, “dark”, and “white belly”. We video sampled the population on multiple days leading up to spawning across five spawning years. Divers focused a laser caliper equipped video camera on individual fish at the aggregation. We later analyzed the video to determine the length of the fish and record the color phase. Our observations show that the relative proportion of fish in the bicolor color phase increases significantly on the day leading up to the primary night of spawning. The increase in the proportion of the bicolor color phase from 0.05 early in the aggregation to 0.40 on the day of spawning suggests that this color phase conveys that a fish is behaviorally and physiologically prepared to spawn. Additionally, 82.7% of fish exhibiting dark or white belly coloration early in the aggregation period suggests that these color phases are not only shown by female fish as was previously posited [Current Zoology 58 (1): 73–83, 2012].This is the publisher’s final pdf. The published article is copyrighted by Current Zoology, Institute of Zoology, Chinese Academy of Sciences and can be found at: http://www.actazool.org/.Keywords: Nassau grouper, Epinephelus striatus, Nuptial coloration, Spawning aggregation, Spawning behavio

© 2004 Kluwer Academic Publishers. Printed in the Netherlands. Observations of a Nassau grouper, Epinephelus striatus, spawning aggregation site in Little Cayman, Cayman Islands, including multi-species spawning information

Mass spawning aggregations of Caribbean grouper species are a conservation priority because of declines due to over-fishing. Previous studies have documented five historical aggregation sites in the Cayman Islands. Today, three of these sites are inactive or commercially extinct. In January 2002, the Reef Environmental Education Foundation led an expedition to Little Cayman Island to document a recently re-discovered spawning aggregation of Nassau grouper, Epinephelus striatus. A team of divers estimated the abundance, color phase composition, and courtship and spawning behavior of the aggregating grouper. The color phase composition of the aggregation shifted both during the course of each evening and throughout the 10-day project. Divers documented atypical coloration and courtship behavior in 10 additional fish species, of which five were seen spawning. Artisanal fishing occurred daily on the aggregation. The Cayman Islands Department of the Environment collected landings data and sampled catches to obtain length and sex ratios. The Cayman fishing fleet, while small, had a significant impact on the aggregation with a harvest of almost 2 000 Nassau grouper during the 10-day project. The study site supports the largest known Nassau grouper aggregation in the Cayman Islands. The relatively large size of fish and the high proportion of males indicate that this site supports a relatively healthy aggregation compared to other Nassau grouper aggregation sites throughout the Caribbean

Appendix D. Plot of data and fitted estimates of site-specific abundance for goliath grouper and mutton snapper.

Plot of data and fitted estimates of site-specific abundance for goliath grouper and mutton snapper

Appendix C. Detailed description of habitat classifications listed in Fig. 1 caption.

Detailed description of habitat classifications listed in Fig. 1 caption

Appendix A. Description of the site-structured demographic model.

Description of the site-structured demographic model