This paper documents attacks by the isopod Excorallana tricornis tricornis on Nassau grouper caught in Antillian fish traps during the post-spawning season of Spring 2005. These findings were documented during Grouper Moon research by REEF and Cayman Islands Department of the Environment staff. Fish were being trapped in order to acoustically tag individuals from sites around Little Cayman Island in order to better understand what percentage of reproductive-size individuals attend the aggregation each year. The paper discusses the apparent energetic costs associated with spawning. This work was also presented as a poster at the 56th Gulf and Caribbean Fisheries Institute Meeting in 2005, and a summary of the poster is posted online (POSTER).
2006
In 2006, researchers from Univeristy of North Carolina Willmington collaborated with Grouper Moon Project researchers from REEF and Cayman Island Department of Environment to conduct mobile hydroacoustic surveys on the Little Cayman spawning aggregation site. Hydroacoustics, which is similar to a fish finder device found on a recreational fishing boat, but with better resolution and technology, has emerged as a valuable tool in fishery population assessments. The goal of the study was to determine the utility of this emerging technology to assist in the estimation of density, spatial extent, and total abundance of a Nassau grouper. This report summarizes the field effort and findings.
This study analyzed temporal trends of the yellow stingray in the Florida Keys National Marine Sanctuary (FKNMS) as recorded by trained volunteer divers using the Roving Diver Technique. Data were obtained from the REEF Fish Survey Project. A generalized linear model on presence-absence data was used to estimate the change in yellow stingray by year. Habitat type, bottom time, depth, site, water temperature, and Julian date were included in the model to standardize the data. The decline in sighting frequency has occurred in all habitat types, depths, sites, and regions of the FKNMS. Within the FKNMS yellow stingray sightings declined from 32% SF (425 sightings in 1323 surveys) in 1994 to 8.5% SF (93 sightings in 1095 surveys) in 2005, averaging ~18% decline per year. The decline has gone virtually unnoticed. This study highlights the importance of protecting marine communities for the preservation of fishery resources and shows the importance of recording all marine species extractions. It also demonstrates the value and application of trained volunteer divers for monitoring temporal trends and species interactions of marine communities. This work was presented at the Summer 2006 American Elasmobranch Society meeting in New Orleans.
2005
The Cayman Islands Department of Environment needs to assess the effectiveness of Nassau grouper (Epinephelus striatus) spawning aggregation site closures by gaining a better understanding of how local grouper populations use the ag- gregation sites. During the January 2005 spawning season thirty Nassau grouper were acoustically tagged off the Little Cayman west end aggregation site and during the summer of 2005 an additional twenty Nassau groupers were tagged around Little Cayman. By tagging fish on the aggregation we have been able to determine where fish go after they leave the spawning aggregation. By tagging fish around Little Cayman prior to the 2006 spawning season we will be able to de- termine the proportion of fish from around the Island that attend the west end spawning aggregation. Also, the frequency of aggregation attendance by individual fishes as a function of demography will be assessed. Initial results show that 60% of the groupers tagged during the January, 2005 aggregation returned to aggregate during the February full moon. Further- more, these 18 returning fish were amongst the largest of the 30 tagged. Ultimately, this information will allow us to assess the current and future impacts of protections afforded Cayman’s spawning aggregations. Moreover, the study will define an aggregation’s “sphere of influence” both geographically and demographically and will thus aid in the management of local Nassau grouper populations.
This study used REEF data from Bonaire, an area where several thousand REEF surveys have been conducted, to evaluate patterns in species occurrence. Their results suggest that species interactions, and/or species-habitat relationships may be important behavioral attributes mediating the local structure of fish assemblages on these coral reefs. This work was also presented at the International Coral Reef Symposium in 2004.
Though declines in coral health have been documented worldwide, the effects of this decline on reef inhabitants are poorly studied. Studies monitoring fish abundances through coral declines are often inconclusive or contradictory in their results. This study uses fish assemblage data from REEF's database, as well as bleaching data compiled by ReefBase and reef health data collected by Reef Check, to correlate reef inhabitant abundance with bleaching events. Data are analyzed with respect to species, reef location, bleaching severity, and recovery time. Preliminary results show that the majority of species do not change in abundance following a bleaching event. Of those that do change, both increases and decreases are seen, and the direction of change, even within a single species, is often dependent on the time since the event. This suggests that a local decline in coral health may not have an immediate negative impact on the community and that a window of opportunity to preserve community structure following coral mortality may exist. This work was presented at the Summer 2006 International American Society of Limnology and Oceanography (ASLO) meeting in Spain.
2004
Sightings data submitted to REEF's Exotic Species Sighting Program through 2002 are summarized in this paper. The data show a hot-spot of non-native marine fishes along south Florida (Broward and Palm Beach Counties). The authors evaluated potential vectors of introduction and pinpointed the aquarium trade as the likely source.
This paper summarizes the finding from the 2002 REEF Grouper Moon Project, which documented the characteristics of a newly discovered Nassau grouper spawning aggregation. At its peak, over 5,000 Nassau grouper were present at the site. Significant contributions include the visual and video documentation of four nights of spawning of Nassau grouper, the description of crepuscular and lunar movements and color phase shifts in the grouper, and the documentation of courtship/spawning behavior in ten additional species. This paper was also presented at the 2002 Gulf and Caribbean Fisheries Institute Meeting.
This paper evaluates two sets of fisheries-independant data on Goliath grouper populations in Florida. The datasets include the REEF Survey Project database and personal observations from a professional spearfisher. Because all harvest of this species was prohibted starting in 1990, fisheries-independant data like these are critical to understanding change in the populations, including any recovery that may be occuring. The paper also provides information on standarization techniques that can be applied to the REEF data.
Report prepared for the South Atlantic Fishery Management Council, the Gulf of Mexico Fishery Management Council, and the National Marine Fisheries Service
REEF data were one of three datasets used in the most recent stock assessment of the Goliath grouper, a species that is currently protected from harvest due to very low numbers in the 1980s. Because this species is not fished, fisheries managers must use fisheries-independent datasets and the REEF database represents a valuable source of this information.