This paper describes several models to convert order-of-magnitude count data that are collected during REEF Roving Diver Technique (RDT) surveys to a numeric mean, and demonstrate that with a sufficient number of surveys, estimates of the mean with a reasonably small confidence interval can be attained. For each model, parameter estimates and associated confidence intervals were derived from 292 RDT surveys where precise counts were also made. Models were compared using the small sample Akaike Information Criteria (AICc). The best-fitting model uses disaggregated bin-count data and considers the relative proportion of counts in adjacent bins. A companion paper was published in the same CalCOFI issue that uses the model to evaluate population trends in rocky reef fish species along the Monterey Peninsula region in central California.
2013
A database of fish surveys conducted by volunteer recreational divers trained by REEF was used to examine fish populations in Monterey Peninsula, California, between 1997 and 2011. Over 3,000 surveys were conducted as part of this ongoing citizen science effort. The analysis was conducted using a numerical conversion method to calculate population estimates from REEF log-scale data (this method was described in a companion paper published in the same CalCOFI Reports issue). Variations in relative density over time are reported for 18 fish species, including several fisheries-targeted species. Two recruitment pulses of young-of-the-year rockfish (Sebastes spp.) were observed over the study period, with subsequent increases in older rockfish. Several predator species increased and subsequently declined, peaking two years after prey populations. Strong concordance was found between REEF data and those collected by Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), a consortium of academic institutions. Results show that data collected by REEF has great potential to augment and strengthen professional research data and serve as a valuable baseline to evaluate marine reserves.
Despite being the world’s largest rays and providing significant revenue through dive tourism, little is known about the population status, exploitation, and trade volume of the Mobulidae (mobulids; Manta and Mobula spp.). There is anecdotal evidence, however, that mobulid populations are declining, largely due to the recent emergence of a widespread trade for their gill rakers. Researchers from Dalhousie University and eShark.org used expert divers’ observations from two citizen science programs, REEF's Volunteer Fish Survey Project and eShark.org, to describe global manta and devil ray abundance trends and human use patterns. The study highlights the relative rarity of aggregation sites on a global scale and reveals that many populations appear to be declining. The authors warn that newly emerging fisheries for the rays gill-‐rakers likely exceed their ability to recover. The study also demonstrates the deficiency of official catch reports, as only four countries have ever reported landing manta or devil rays– Indonesia, Liberia, Spain and Ecuador. However, numerous diver reports compiled in the paper illustrate that many other countries are regularly landing and selling these rays without reporting.
In response to conservation concerns for inshore rockfish, Fisheries and Oceans Canada implemented a system of 164 rockfish conservation areas (RCAs) in British Columbia as part of the Rockfish Conservation Strategy. RCAs were established between 2004 and 2007. RCAs are not marine protected areas (MPAs) because they were not designated though any MPA legislative tool such as Canada’s Ocean Act, but rather through a fishery closure using the Fisheries Act. They can, however, be considered harvest refugia. Evaluations of the performance of RCAs have recently been undertaken by government agencies, academics, non- governmental organizations (NGOs) and First Nations. This report describes the most recent scientific research on RCAs. Research has been done using remotely operated vehicles (ROVs), scuba surveys, hook-and-line fishing surveys, genetic analysis and compliance monitoring. Although some empirical research shows some RCAs are demonstrating an effect, most have not shown statistical differences in rockfish density among RCAs and non-RCA sites. One reason for this might be that RCAs are still considered to be “new” or “young” and it is thought that rockfish will take numerous years to respond to protection. REEF survey data for inshore rockfish and greenling species from Whytecliff Park between 1998 and 2013 were included in this report. Whytecliff Park is in West Vancouver, and was made the West Vancouver RCA in 2006.
2012
This paper is part of the larger body of genetic research being conducted on Nassau Grouper in the Caribbean. The authors identified ten polymorphic microsatellite loci for Nassau grouper (Epinephelus striatus) by cross-amplification of loci isolated in Gulf coney (Epinephelus acanthistius). Samples from three geographic localities were scored for these loci –Glovers Reef off Belize (n = 50), Little Cayman (n = 50) and Grammanik Bank in the U.S. Virgin Islands (n = 50). Screening samples yielded 8 to 27 alleles per locus with observed levels of heterozygosity ranging from 0.30 to 0.96. Markers will be used in a Caribbean-wide study of Nassau grouper to understand patterns of genetic connectivity, as well as to contribute to fisheries management and conservation.
This paper presents a key technique that scientists from REEF and our Grouper Moon collaborators have used to monitor fish on the Little Cayman spawning aggregation that does not require the capture and handling of fish. We show that length-distribution data can be collected by divers using a video-based system with parallel lasers calibrated to a specific distance apart, and subsequently use those data to monitor changes in the size distribution over time.
Climate change is expected to cause a poleward shift of many temperate species, however, a mechanistic understanding of how temperature and species' life histories interact to produce observed adult range is often lacking. The authors evaluated the hypothesis that juvenile thermal tolerance determines northern range in gray snapper (Lutjanus griseus), a species commonly caught as juveniles along the US Atlantic coast well north of their adult distribution, using a combined laboratory, field and modeling approach. To evaluate the relationship between juvenile thermal tolerance criteria and adult distributions, the authors used the REEF database to quantify adult distribution. There was a strong correspondence between observations of adult gray snapper from the database of recreational divers vs. latitude with that of the predicted survival of juveniles vs. latitude from their modeling analysis. The agreement between the laboratory-derived thermal tolerance metrics, the spatial distribution of winter temperature, and the distribution of adult gray snapper support the hypothesis that the adult range of gray snapper is largely limited by the overwinter survival of juveniles.
This paper explores detectability rates of lionfish using underwater visual census methods such as belt transects and stationary visual census. Knowing the error in these methods specficially for lionfish is necessary to help study this invasive species in the western Atlantic. The research was conducted at the Cape Eleuthera Institute, where much of REEF's work on lionfish is conducted.The authors found that the two census methods detect fewer than 30% of lionfish present in an area and, in more than 50% of the cases, fail to detect any lionfish when one or more indivudals are actually present. Two factors affected the ability to detect lionfish: lionfish body size and habitat complexity.
This paper features research findings from powerful genetic techniques and the REEF survey data that reveal two new species of hamlet in the Caribbean. As REEF Caribbean surveyors know, hamlets are a group of colorful small sea basses that can sometimes cause ID confusion because of their myriad of colors and patterns. The varied color patterns in these small predators are thought to be a result of mimicry of other colorful herbivore species. There has been ongoing debate in the scientific world about which are actual species and which are simply just color variants or morphotypes. The research featured in the paper revealed significant genetic differences among what seemed to simply be variations of the well-known Barred Hamlet. The two new species are the Florida Barred Hamlet, Hypoplectrus floridae, and the Contoy Hamlet, H. ecosur. The typical Barred Hamlet (H. puella) that is found throughout the Caribbean will be updated to be called the Caribbean Barred Hamlet. Florida Barred Hamlet have been found in the eastern Gulf of Mexico and South Florida, and it overlaps in range with the Barred Hamlet in those area. At the time of publication, the Contoy Hamlet had only been documented on Isla Contoy near the northern tip of the Yucatan peninsula and possibly Isla Mujeres. Florida Barred Hamlet are distinguished by a pair of symmetrical dark spots at the base of the caudal fin along with a break in the mid-body narrow bar. The Contoy Hamlet is distinguished by the same paid of dark spots at the base of the tail as well as a series of additional dark spots along the upper caudal peduncle and below the dorsal fin.
There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems. Lead author, Stephanie Green, from Simon Fraser University (SFU), along with REEF Director of Special Projects, Lad Akins and other co-authors Aleks Maljković (SFU), and Isabelle Côté (SFU), documented a dramatic 65% decline in 42 species of reef fish eaten by lionfish over a two year period. The study, conducted off New Providence Island in the Bahamas, used data collected during REEF's volunteer lionfish projects to track the explosion of the lionfish population over time, and revealed that lionfish biomass increased from 23% to nearly 40% of the predator biomass on the study sites between 2008 and 2010. This study represents the first documented direct impact of lionfish predation on native reef fishes and highlights the importance of control programs to minimize impacts.