By LARRY SMITH
MARSH HARBOUR, Abaco – Since 2004, Abaco’s home-grown conservation group - Friends of the Environment - has staged a two-day conference every two years that brings together scientists, students and the public to discuss important research.
According to Olivia Patterson, who coordinated the most recent meeting, “as we were helping more and more researchers with their logistics, we decided to provide an opportunity to share this research with the community. We also wanted to make sure that the information is available for education and to help inform decision-making for sustainable development”.
This year’s event featured more than a dozen presentations on topics like coral reef decline, mangrove restoration, endangered birds, plant biodiversity, seawater quality, and landscape change on Abaco 900 years ago. Sponsors included RBC Royal Bank, J S Johnson and New Vision Ministries.
One of the most important presentations was by Martha Davis, of the non-profit research group Community Conch. Davis has a graduate degree in marine conservation from Scripps Institute of Oceanography. In 2009 she teamed up with top conch biologist Dr Alan Stoner and environmentalist Catherine Booker to study conch fisheries in the Bahamas.
“Our mission is to effect the sustainable harvest of queen conch through research, education and collaboration with local communities, the government and other organisations,” Davis said. “Conch has been a primary food staple for Bahamians, but has recently become threatened by over-exploitation.”
The regional history of conch fisheries is instructive. In the Florida Keys the fishery collapsed in 1975 when commercial harvesting was banned. A few years later, commercial and recreational conch fishing was banned in all Florida waters.
Bermuda’s conch fishery also collapsed in the late 1970’s. And despite strict regulation, neither fishery has recovered. Other countries such as Jamaica and Cuba have been forced to use fishing moratoriums repeatedly over the last decades to prevent over-fished stocks from collapsing.
“The Bahamas is fortunate to have comparably vast areas of suitable conch habitat and a relatively small human population size, which has allowed the harvest of conch to continually increase when it seemed all other nation’s stocks were in trouble. But today, the signs of stock decline in The Bahamas are undeniable,” Davis said.
“We started our research five years ago and have published four papers so far,” she added. “We started in the Berry Islands, moved to Andros, then to the Exumas, and then to Abaco. Last year we researched the Jumentos Cays and Ragged Island, and this summer we will be working on the Little Bahama Bank, giving us nationwide coverage.”
The target areas for research are identified by the Department of Marine Resources and refined after consultation with fishermen. Volunteers then count adult and juvenile conchs, mating pairs and egg casings in these areas – either towed behind boats in shallow water or scuba diving in deep water. They also measure shell lip thickness, which determines age and sexual maturity.
The drop-dead number from all this research is 50. That is the density of adult conch per hectare required for successful mating. And Community Conch has confirmed that in every commercial fishing ground surveyed over the past five years there are less than 10 conchs per hectare – a density which cannot sustain reproduction.
Community Conch’s academic guru is Dr Alan Stoner, who began his career at Florida State University and joined the US National Marine Fisheries Service in 1996. Over the last 25 years, Stoner and his research partners have published more than 50 peer-reviewed papers on queen conch, and the function of marine protected areas.
It was Stoner who, in 1996, showed that densities of adult conch on the shallow bank around Warderick Wells in the Exuma Cays Land and Sea Park were 31 times higher than densities in comparable habitats with moderate fishing pressure near Lee Stocking Island.
Since that study, fishing pressure has grown with higher demand for seafood and increased use of compressed air by conch divers. As a result juveniles are being harvested illegally, and previously inaccessible deepwater stocks are being exploited, leaving no refuge for conch reproduction.
At the Abaco conference, Davis discussed the latest research. In 2012 Community Conch investigated key fishing grounds in the Bight of Abaco, off Sandy Point and More’s Island. In the Sandy Point area densities averaged just over six conch per hectare, and were about 10 conch per hectare west of More’s Island. Average lip thickness ranged from 6 to 9mm, indicating very young populations.
Most male conch do not reach sexual maturity until their shell lip thickness reaches 10 mm, and most females are not sexually mature until the lip thickness is 15 mm. The conclusion is that conch with a lip thickness of less than 15 mm should not be harvested. Only three mating pairs among more than a thousand flared lip conch were encountered during two weeks of survey work in these areas.
“It is clear that conch fishers in the Bight of Abaco have become dependent upon compressed air and deepwater populations of adult conch are now relatively rare on the traditional shallow-bank grounds,” the research report said. We predict that the Sandy Point and More’s Island conch fishing grounds are approaching collapse.”
Last year, Community Conch researched the Jumentos Cays and Ragged Islands between Water Cay in the north and Little Ragged Island in the south. The average density of adult conch in this region was 122 per hectare, with density decreasing from north to south.
“The number of mating pairs observed revealed that most mating occurred at densities over 85 adults per hectare,” the report said. “This corresponds closely with other lightly fished areas in the Bahamas and supports the recommendation that management for the species should be designed to achieve minimum densities of 100 adults per hectare.”
The report concluded that “based on the collection of data over five years in 10 conch fishing grounds, there is a clear trend for local conch populations to be overfished to densities incapable of reproduction, and for densities to increase with distance from human settlements.
“The best example of a fully functioning population other than in the Exuma Cays Land and Sea Park (where fishing is prohibited) is the significant adult breeding population in the most remote part of the Jumentos Cays.”
Based on their research, Community Conch offered the following recommendations:
Establish marine protected areas, fishery co-operatives and a sustainable fishery certification programme.
Update regulations related to minimum lip thickness, quotas, closed seasons and use of hookahs.
Develop area-specific management plans for each major conch resource.
Research population connectivity and the impact of discarding knocked conch in active fishing grounds.
Evaluate the impact of ending conch exports.
Most of the conch available for international trade is purchased by US importers. And conch has been legally exported from the Bahamas since 1992. About 600,000 pounds leaves the country every year, which only increases fishing pressure on our dwindling conch stocks.
It makes little sense to allow the export of hundreds of thousands of pounds of conch meat every year, while watching the decline of this key Bahamian fishery. Over the years conch fisheries have been closed throughout the Caribbean. Do we really want to see the end of this important cultural catch in the Bahamas?
Gilpin Point Bones
On a beautiful ocean beach just south of the Crossing Rocks settlement lies a complex prehistoric site unlike anything else discovered in the Bahamas. Following a presentation at the Marsh Harbour conference, Dr David Steadman of the University of Florida at Gaineville led a field trip to the site – known as Gilpin Point.
Steadman, along with landowner Perry Maillis, Nancy Albury of the Antiquties Corporation and others recently published a paper on the site in the scientific journal Holocene titled Faunal and Landscape Change in the Bahamas.
The paper describes a bone-rich peat deposit radiocarbon-dated to about 900 years before the present that is exposed today only for brief periods at very low tide. The deposits and the bones represent a vertebrate community at the time of first human presence in the Bahamas, and only 10 of the 17 identified species of amphibians, reptiles, birds, and mammals still live on Abaco.
“We think the peat was laid in a freshwater estuarine system when the coast was further out,” Steadman said. “There are buttonwood stumps, which are freshwater mangroves, in upright growth position, so the sea level had to be lower and rising sea levels killed off the buttonwood.
“We also found extinct tortoise shells with crocodile bite marks like those found in the Sawmill Sink blue hole, as well as lots of sea turtle bones with bite marks. Some shells are burned on the outside with teeth marks on the inside, indicating that humans butchered and feasted on the turtles and then crocodiles scavenged the remains.”
Lucayan Indians arrived on Abaco about 900 years ago, which is the estimated age of the peat deposits. Although there have been written references to “serpents” in the Bahamas ever since Columbus, Gilpin Point provides the first physical evidence that crocodiles and humans co-existed on the islands. Among the finds in the peat was a polished Lucayan shell bead.
Human involvement in deposition of bones at Gilpin Point is supported further by the dense, midden-like concentration of large bones (crocodile, green turtle, and tortoise) in the peat, and the fact that some bones of both the green turtle and Abaco tortoise are charred.
“Our failure to find any pottery or rich shell midden at Gilpin Point might be due to inadequate sampling,” the researchers said in their paper. “If the site extends inland beneath the beach ridge (which seems likely), then the peaty sediment that we have observed would represent less than 1 per cent of the entire site.”
The fact that many of the animals whose remains were found in the peat no longer live on Abaco should be cause for concern, according to Steadman. “It shows that even prehistoric people with simple tools and weapons can have a significant effect on the environment. We don’t want to lose more than a third of our fauna over just 900 years. That puts our current environment in better perspective – knowing that we have already lost a lot.”
Sea level when the peat deposits were formed was about eight inches lower globally, Steadman said, but probably lower locally, and the current beach was the landward side of a lagoon.
“At both the local and regional scales, these low islands can be affected dramatically by changes in sea level. Over the last century sea level has risen between 6 and 16 inches, which may not sound like much unless you own a condo on the beach.”
The Gilpin Point site was discovered by Sabrina Bethel and Perry Maillis in 2009, during a very low spring tide. The dark, peaty sediment at Gilpin Point is inundated today by the ocean under normal circumstances, as well as being covered by sand.
“A challenge now is to search the beaches of Abaco’s windward side to begin to learn whether the Gilpin Point site is truly unique or merely represents a more common situation that heretofore has been overlooked,” the journal paper concluded.
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