Stone crabs have been a popular and principal commercial fishery in Florida for many years, and have comprised a portion of the local fishing take here in The Bahamas for just as long. Recently, there have been reductions in Floridian catch, as well as an increase in fishing pressure for the crabs in the Bahamas, where they now represent the fourth largest fishery. With growing commercial demand and the arrival of new commercial export pressure in North Eleuthera, stone crab trapping in South Eleuthera may soon increase. Though the fishery is presumed to be sustainable – harvest restricted to legal-sized regenerative claws suggests less than 100% mortality – little is known about stone crab populations in The Bahamas and specifically around the Cape.
This semester Claire Thomas, manager of the Sustainable Fisheries Program at CEI, and Alicia Hendrix, CEI research assistant, are leading a research class for students at The Island School hoping to address the lack of information on South Eleuthera’s stone crab population. Using commercial fishing traps, students are collecting data on crab abundance, carapace width, propodus length, and sex that can provide insight into the local fishery. A better understanding of the current population will allow for comparisons in the future, and help identify any actions that may be needed to insure the longevity of this growing fishery. Students are also collecting data regarding water temperature, depth, and bottom type in surveyed areas to better understand the habitats stone crabs like to frequent here in The Bahamas. Continue reading →
The summer season at Cape Eleuthera Institute always sees a tremendous amount of activity. Visiting scientists fly in, new interns and undergraduates arrive, and every now and then our own researchers spend some time off-island diversifying their studies. This past summer, Lionfish Research Program RA Alicia Hendrix headed to Honduras to lead work with UK-based organization Operation Wallacea, which offers volunteers a chance to assist scientists at field sites around the globe.
The Bay Islands of Honduras offer a unique research opportunity to contrast divergent fishing pressures on Caribbean lionfish communities. Two sites – the Bay Island of Utila off the coast of La Ceiba and Tela, a mainland site just a few hours away – support very different reef-based economies. Utila, a widely known and popular dive destination, is home to a dozen dive shops most with active lionfish culling programs, but is not a primary fishery for more commonly consumed Caribbean staples. Tela, a site far less frequented, has been subject to harsh overfishing in past years, supports a reef fish community recovering from those pressures, and currently experiences little in the way of lionfish culling. Contrasting the two can give researchers an idea of how factors such as lionfish spearing, regular exposure to divers, and more broadly targeted fishing practices might affect lionfish distribution and behavior. Continue reading →
Gap Year students spent an afternoon with the sustainable fisheries program, dissecting lionfish and engaging in discussion about the invasive species. During the dissection students poked at lionfish visceral fat and removed the fishes’ venomous spines, among other organs. The dissection was a hands-on way to see how these habitat and feeding generalists thrive in the Bahamas. They eat during all hours of the day and, as a result, have more visceral fat than most fish. Understanding mechanisms which make lionfish such successful invaders is an important first step to effective management of the species.
After learning about the latest research regarding lionfish prey preferences and feeding habits, Gap Year students headed into the field to try their hand at catching prey fish for the lab. Armed with fins, snorkels, and hand nets, the team of 5 targeted juvenile fish which could be used in lab choice trials. Despite initial setbacks (catching fish has a learning curve!) the excursion was ultimately a success and a collection of damselfish, silversides, and grunts made their way back to the CEI wet lab.
This past summer was a busy time for the sustainable fisheries team, with numerous conch and lionfish lab trials.
On the lionfish side of things, Helen, one of the visiting Newcastle students, is looking at prey density as well as whether or not it benefits lionfish to hunt in groups. She does this by adding 1 (or more) lionfish to a tank containing varying densities of prey fish (grunts) and observing the rate at which the grunts are eaten. Emily (another student from Newcastle University) is exploring prey preference in lionfish. She ran a series of trials to determine whether lionfish are more likely to attack a grunt or a damselfish if given the choice. She is now determining if lionfish rely more on visual or olfactory signals when hunting.
Oli, a third student from Newcastle, was running behavioral trials on conch. A fisherman’s tale suggests that the declining numbers of conch available is due to the fact that the animals run away from knocked shells that have been thrown back into the water by other fishermen (as opposed to overfishing). Oli is testing this explanation by dropping empty conch shells (as well as rocks as a control) in a tank with a live conch and monitoring its movement for 4 hours. We will keep you updated on the results of these trials as they progress!
Queen conch are an important animal in The Bahamas, both economically and ecologically. Conch reproduce via internal fertilization and females lay extensive egg masses that hold hundreds of thousands of eggs. However, recent years have shown a marked decrease in conch populations, in the greater Caribbean region, and in The Bahamas.
In 1993, dive and tow surveys were conducted that assessed the breeding populations of conch off Cape Eleuthera. This summer we are reinvestigating this area to determine whether conch are still utilizing the same breeding grounds as they did in the 90s, and if their population is undergoing any variation or decline.
To accomplish this, CEI is running a series of conch tows and dives to assess conch population density. This involves either pulling researchers behind a boat or diving in small groups and noting how many conch are present as well as the size category of those conch (either adult, subadult, or juvenile). These size categories have to do with the age and sexual maturity of the conch and are determined by the presence and thickness of a flared lip on the conch’s shell. We will continue to update you on our findings throughout the summer.
This year, CEI had a booth at Deep Creek’s Homecoming, called Conch Fest, that was geared towards promoting sustainable fisheries. The team was frying up lionfish samples, so local community members can sample the invasive fish that is abundant on the reefs, but also delicious to eat. The team was also promoting the “You slay, we pay” campaign, where fishermen can bring in lionfish, fillets or whole fish, to sell to CEI. The goal is to create a market for lionfish on Eleuthera.
Aside from free fish, the team also had a board with conservation trivia, hoping to dispel some common misconceptions. For example, do green turtles eat conch? The answer is no! Green turtles eat plant material like turtlegrass, and their serrated jaw is perfect for this type of diet.
The booth was open for two nights, and hundreds of lionfish samples were handed out. Thanks to everyone who participated, and the team enjoyed the opportunity to spread the word about the invasive lionfish and what we can do to help (Eat them!).
Congratulations to all of the Spring 2014 Island School students who gave oral and poster presentations at the Research Symposium. This event is a culmination a semester-long research class, where students become involved in all aspects of research. It is a chance for them to showcase the data that they collected, along with real world implications of the work.
We had many special guests in attendance this semester:
David Knowles, Director of Parks, Dr. Ethan Freid, Chief Botanist, and Camilla Adair Deputy Preserve Manager at Leony Levy Preserve, the Bahamas National Trust
Dr. Andy Danylchuk, past Director of the Cape Eleuthera Institute and currently Assistant Professor of Fish Conservation at UMass Amherst, collaborator with Flats Ecology program at CEI
Dr. John Mandelman, Director of Research and Senior Scientist at the New England Aquarium, collaborator with Shark Research program at CEI
Dolphinfish (aka mahi mahi or dorado) are a highly sought after sportfish targeted by offshore anglers, and they also support commercial fisheries in the Caribbean and US. Until recently, little was understood about their movements, stock ranges, and population structure. Recent findings suggest that these fish complete long-distance migrations and are quick to mature. However, little information exists about dolphinfish movements or harvest in The Bahamas – a location identified by the South Atlantic Fisheries Management Council in critical need of further stock assessment.
The Cape Eleuthera Institute has been working with the Cooperative Science Services’ Dolphinfish Research Program (DRP; http://www.dolphintagging.com/) to mark dolphinfish in The Bahamas with external tags (fig. 2). After recording the fish’s size and location of capture, the fish is tagged and released to be captured again by an angler or commercial fisherman. Upon recapture, essential information such as distance travelled and growth of the fish can be determined.
Recent recaptures in the Bahamas have further demonstrated both the distances travelled by dolphinfish, as well as the large geographic range of the north Atlantic stock. One fish tagged in Florida last year was recaptured 309 days off Rum Cay in the southern Bahamas. It is estimated that the fish travelled up the East Coast of the US before swimming back to the Bahamas – a total of nearly 4,000 miles (fig. 3)!
These findings are critical to protecting the Atlantic mahi fishery. By quantifying movements of dolphinfish across political boundaries (i.e., US, Bahamas, Puerto Rico, and other Caribbean nations), a regional management plan can be devised and enforced, ensuring a sustainable fishery for all countries.
If you will be fishing in the Bahamas and are interested in tagging dolphinfish, contact firstname.lastname@example.org, or visit the DRPs website. Many anglers release small dolphinfish; tagging is a great way to contribute to our increasing knowledge of this economically important species!
Last week, the Island School campus was inundated with the parents of the Spring 2014 students. Aside from campus tours and a breathtaking art gallery, parents also got to witness the students give scientific research presentations pertaining to the research projects they have been involved with all semester.
Each presentation was ten minutes long, and followed the format of a professional scientific presentation, explaining background on the topics, the current problem, the methods used to collect data, data analysis, and interpretation of results, ending with why the project matters and what can be done in the future. Parents were thrilled to see the young scientists give their first real talk in front of a large audience. Each student group also fielded questions from the parents.
A town hall meeting was held on May 15 at the South Eleuthera Mission. This meeting was organized by Deep Creek Middle School students who formed a Sustainable Fisheries team: Dimitri Rolle, Oriana Carey, and Sidhira Johnson. Dimitri was the leader of the group. He is particularly passionate about overfishing and sustainable fisheries, and he decided, with the group, that gathering community members to talk about the issue would be a great way to learn about the issues and explore some solutions.
The meeting was the culmination of their DCMS community outreach project. These students took the initiative to plan this meeting, and there was a great turnout, with over 30 young people attending.
The night started with a presentation from Claire Thomas, who manages the Queen Conch Research Program at the Cape Eleuthera Institute. She talked about the problem of conch overfishing, specifically in the Bahamas, and then addressed some potential solutions to overfishing. After the presentation, Oriana and Sidhira divided the audience into three groups, and each group discussed a potential solution: a closed season for conch, a marine protected area, and a lionfish fishery. The idea for the discussion groups came from the DCMS Sustainable Fisheries team, and the discussions were lively, with a lot of participation from the audience. Continue reading →