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Helping to Sustain a Way of Life in the Bahamas

Fishing grounds and marine reserves…what a conch-trast!

By Catherine | 31 July 2011 | No Comments
Published in Exuma Cays Expedition 2011, Uncategorized
As I’ve said before, we were very lucky to have a great group of volunteers again this year. People came from a variety of backgrounds and places, and so all had their own unique impressions of The Bahamas and the studies we are doing. Adric Olson was our only volunteer who stayed for the duration (full five weeks) of the trip. He counted a lot of conch and spent lots of time in the water at both the Lee Stocking Island study site and the Warderick Wells site. Adric was a great person to have around because of his positive attitude and sense of humor. He has the observation skills of a scientist, and always had a good question or suggestion. Here is Adric’s unique perspective…and our attempt to explain some of the finer points of fishery conservation science….
I would be remiss if I didn’t start my blog post by thanking those who made this trip possible for me. It has been a great experience and so I’d like to say thanks to Community Conch and the staffs at both the Perry Institute for Marine Science and the Exuma Cays Land and Sea Park, in addition to those who provided funding for the trip.

Adric found one of the oldest conchs we saw on the whole trip. photo by C. Booker

As I am one of the few people who was lucky enough to participate in the field work for the entire 5-week duration, I have a unique perspective on the quality and quantity of queen conch stocks in the Exumas. As you may have read, the number of conchs we found around Lee Stocking Island is small enough to be troubling, particularly in the deeper waters. This depletion is even more troubling when the numbers are compared with those reported by Dr. Alan Stoner’s from his studies done in 1991 (Stoner and Ray, 1996). (I’m sure this will be discussed in a much more scientific manner in the paper that will be published as a result of our work, so I will try to avoid mentioning specifics here). Although we did find a lot more conchs in the shallower areas around the Lee Stocking study area, they were very young which further compounded our concern. Although this may seem like a positive sign for the future of the conch, the reality may be much bleaker. A large amount of scientific research has shown that fishing pressures can drive the average size and age of commercially harvested species so that stocks become both smaller and younger, followed by a collapse of even the most expansive stocks (See: Beluga Sturgeon, Atlantic Cod, and queen conch in other countries of the Caribbean!).

Adric and Jasmine get ready for a dive. photo by C. Booker

The good news it that we saw a lot more queen conchs in the Exuma Cays Land and Sea Park than we did around Lee Stocking Island. The density of conchs  (the number of conchs per hectare) was much greater, which is a good sign. Scientists are interested in measuring density within a population because generally, the more conchs there are in an area, the greater chance they have of finding each other and reproducing. And the larger the population (or number of individuals), the more likely it is that density will also be greater. But to have a proper discussion about the conch stocks in the Exuma Cays Land and Sea Park, a basic understanding of source-sink and meta-population dynamics is necessary.
Metapopulations come into play in fisheries when population groups (often called sub-populations) of a species are separated and small, so that the possibility of individuals from different populations finding each other and reproducing is virtually eliminated. In the case of the queen conch and other organisms that do not move long distances, the bigger the population and greater the density, the better chance individuals within the population have of finding each other and mating. A good way to visualize this to think about a somewhat cloudy day, where there are lots of distinct clouds in the sky but none of them touch any of the others. Just like the distinct populations found in a metapopulation model, some clouds are bigger than others and some are closer together. In nature, individuals, and therefore genes, can travel between these population “clouds”, depending on proximity, ease of travel, and other factors. This type of model applies for any number of organisms (even humans – North America and Europe are connected by airplanes and boats but the vast majority of those on either continent tend to stay and reproduce on that continent). Source-sink dynamics refer to the exchange between populations. Trouble can occur when one of the clouds is not able to sustain a population without an influx of individuals from another population. This unsustainable area or population is called a sink. The population or populations sustaining it are called sources. The smaller and further apart populations are, the less likely that this necessary exchange will occur.

A graphic representation of Adric's explanation of metapopulations and source/sink dynamics.

Now, how does this pertain to the Land and Sea Park? The expectation is that marine reserves in general will act as sources that support populations outside of the area, but also, hopefully, sustain themselves. If a reserve like the Land and Sea Park is acting as a sink and cannot sustain itself, this could spell doom for populations (like populations of the queen conch) within that reserve if the source populations necessary to sustain it are destroyed. This is why scientists believe that a network of marine reserves is a better management approach, so that there will always be some populations large enough and close enough together so that exchange can occur. So is the Land and Sea Park a source or a sink? Is it sustaining itself? This is a complicated question which can have different answers depending on the species you are considering. Currents in the area and the duration of the larval phase of a species life cycle are important. As for the queen conch, we have some clues based on the population structure inside the Park. Look for our assessment in our next report!
Adric observes a trio of conchs. photo by C. Booker
I’m going to conclude my post by saying nice things about the Bahamas, because I really enjoyed my time there. Almost every Bahamanian I met was exceptionally friendly, to the point that I felt they would oblige me if I needed the shirt off their back. On one notable occasion, I got to go to Big D’s on Great Exuma, where Big D made us the most photogenic conch salad I’ve ever seen (yes, sustainably caught!) and then chatted us up all night. Big D is a big supporter of queen conch conservation. He knows his business depends on it.

"Big D" of Big D's Conch Spot in Steventon, Great Exuma presents his beautiful conch salad and a large adult conch. photo by Karl Mueller

The scenery in the Bahamas was beautiful and the number of mostly undeveloped islands could yield an infinite number of postcard-perfect sights. The Exuma Cays Land and Sea Park was beautiful and I was blown away by the large number of sharks and fish, large and small. The majority of fauna in the Park was flourishing and the only shame is that the other parts of The Bahamas I saw during this trip didn’t look the same way. The Bahamas are a fantastic country with untold treasures and I just hope they are able to make the few changes necessary to preserve their beauty so I can share them with my children someday.

Andy, the conch whisperer

By Catherine | 25 July 2011 | No Comments
Published in Exuma Cays Expedition 2011, Uncategorized

The surveys and our 2011 field season are officially completed! We’ve left the Exuma Cays Land and Sea Park, and the volunteers have traveled back home, but there is still a lot to say. Now with better internet access, I think it would be a shame to stop the blog. As we have more time to reflect on this expedition, I know there will be more for us to share. Scientific results aside, we learned a lot on this trip, and I think it is important to continue the conversation with a broader audience.

So, for our first post-expedition post, we’re going to recognize one of our veteran volunteers, Andy Mclean, who shall now be know as the conch whisperer.

Part of our reproductive study of queen conch this year involved determining whether the animal was male or female. This is very difficult to do without sacrificing the animal, because conchs are very shy. They have that big, hard shell to protect their soft bodies, and they use it whenever they sense danger. If disturbed, a conch may retract its entire body back into the shell and stay there until it is sure that the threat has passed.

The best way to find out if a conch is a girl or a boy is to look for the presence or absence of the male’s reproductive organ, “the verge”. The verge is easy to spot if the conch is out of its shell, though it is very rare (but possible) to catch a conch extending its body far enough out of its shell.

Andy became our expert at using non-invasive, non-lethal techniques to determine the sex of a conch. He was patient. He was non-threatening. He knew just where to look when a conch decided to emerge, and make a “run” for it. (Conchs are very, very slow, so it is really more like a “crawl for it”.) As Peyton put it, “Andy’s got the urge to see the verge emerge.”

We are not sure why this talent would be useful in any other setting, but perhaps you will see Andy featured in his own T.V. show one day…

First, Andy listens to the conchs as he brings them to the surface. photo by C. Booker

 

A fiesty old conch emerges for Andy. photo by C. Booker

 

Andy waits and watches patiently. photo by C. Booker

 

An early attempt at the x-ray vision technique. photo by C. Booker

He’s finally in The Bahamas…counting conchs

By Catherine | 18 July 2011 | 1 Comment
Published in Exuma Cays Expedition 2011, Uncategorized

As a nine year old kid I ordered a set of goggles, snorkel, and fins from Montgomery Ward Catalog.  I taught myself to snorkel in the college pool as my Dad taught his Water Safety Instructor courses.  As the students swam their laps and did their tasks I dove in and among them imagining all kinds of scenarios with me being in the Bahamas; diving the warm Caribbean waters instead of the chlorinated, heated pool at Chadron State College.

In these imaginary adventures there were any number of animals; sharks, rays, morays, and octopus.  Now, years later, (and we won’t count how many…though the reference to the “Monkey Wards” Catalog should give you a hint) here I am actually in the warm waters off the sands of Warderick Wells Cay in the Bahamas.   I’m here having adventures with conch.  Yea, there are sharks, rays, morays and octopus around…be we are concentrating on the queen conch.

Mark "Peyton" heads to surface with a conch.

A friend sent me an email about the Community Conch project and said he thought I might be interested.  I looked into it, and I was.  I contacted Catherine and said I was very interested in coming to the Exuma Cays Land and Sea Park and helping any way I could with the project.   She said come on down.

So I did.  I wanted to observe the methods and protocols of their conch surveys.  We do similar survey work along transects, only in terrestrial habitats.  Our work revolves around the effects of different grazing schedules on grass, invasive weeds, and breeding birds.  One of the major problems is always in insuring your sampling is unbiased and that your subsequent analysis is accurate.  Community Conch has the same concerns and coming from such a different environment to watch and learn from them helps me to evaluate our sampling and our monitoring work.

One aspect of the surveys, towing an observer behind the boat, head and mask in the water looking down and counting conch, reminds me of doing large mammal surveys from an airplane…flying above and counting only those viewed through a special frame on the plane…though in doing that you don’t have to worry about the speed of the plane pulling your swimming suit down to your ankles.  OK, that only happened once!   However, this compare and contrast activity, or “cross fertilization” as Martha calls it, is exactly what I had hoped for.

Peyton waits patiently for a conch to come out of its shell, a technique we call "waiting on the verge."

If nothing else this has been a wonderful change for me.  First, as you would expect, the Bahamas in July are about as different from Nebraska in July as you can get; secondly, I’m working in sea water instead of the open grasslands or the gravel mine lakes that I frequent at home.  Lastly, while I’ve been on any number of recreational dive trips over the years, the diving here is quite different.

Peyton checks out a Bahamian coral reef.

On a recreational dive you are schooled to slow down, relax, don’t exert yourself.  Here, the dives last about 40 minutes with 28 of those minutes consisting of active swimming.  Two divers go down.  One navigates a square while the other searches for conch.  I’ve never been able to stretch out a tank full of air in relaxed recreational diving and with these dives, because of the exertion; it is a challenge for me to simply get to the anchor again before I begin to run low on air.   However, they are working around my limitations and I’m really enjoying the dives.

Today, however, I won’t be diving, I will again don the snorkel, mask, and fins and we will go looking for conch in shallow areas.  Once we locate the conch we will free dive and try and find individuals that fit the size range we need for our study.

Mark shares another good story.

Our two-week adventure is drawing to a close and it has been great.  The weather has been very good, the diving fun, and the people I’m working around fantastic. All things come full circle and today, years after playing out my dreams in the pool, I’ll grab my  snorkel and fins and live those dreams of diving in the clear, warm waters of the Bahamas.

-Peyton

Big or small, we love them all!

By Catherine | 15 July 2011 | No Comments
Published in Exuma Cays Expedition 2011, Uncategorized

Over the past few weeks we’ve seen lots of queen conch. We’ve spent what amounts to days and days in the water and covered miles (or kilometers) of seabed in search of these animals. Each day the crew from the dive boat and the crew from the tow boat compare notes. Where did you go? How many did you see? How big? Any mating? Eggs? How old were they?

After listening to these daily reports and seeing hundreds of conch myself, I am amazed by the variety of shell sizes and shapes within the species, Strombus gigas. This variety is likely due to a combination of genetics, the kind of the habitat the conch is living in, and the age of the animal. In a previous post I briefly talked about the differences between juveniles, rollers, and adults (a little more on that soon), but for this post I am really talking about the adults.

A thin-lipped, "young adult" queen conch shell at Warderick Wells. photo by C. Booker

Measuring the flared lip of an older adult conch shell. photo by M. Peyton

Here in Warderick Wells the dive crew is finding a lot of older conchs in the deeper waters we are exploring. Most of the old conchs we find have shells that are very rounded and have long since lost the beautiful pale pink on the outside of their shells. They are extremely heavy because of the layers and layers of calcium carbonate shell the animal has built up over the years. The younger conchs the towing crew finds generally have a much more delicate appearance because their shell has not been worn down over time and the beautiful hues of pinks still stand out. So, age does obviously make a difference in the appearance of the conch.

A conch covered in algae. photo by C. Booker

All animals are shaped by their environment, and the queen conch is no different. The appearance of a conch shell is very influenced by the biological environment it lives in. Fishermen know that a conch’s shell tends to take on certain characteristics of its habitat and are not fooled by this “disguise”. Our towing team has had a great time trying to spot conchs disguised by lots of algae growing on their shell that resemble little “Chia pets”, or “rasta conchs” (depending on who you ask).  These guys blend into their habitat really well! Towards the end of a conch’s life the thick shell has almost certainly become a little ecosystem itself.  We’ve seen many different species of algae, some corals, and boring worms in the oldest shells.

Another reason for such great variety in the conchs we have seen may have to do with their genetic “flexibility”, or what scientists call phenotypic plasticity. Most immobile (or less mobile) animals can change the way their genes are expressed based on the habitat they live in. Scientists think that depending on the habitat (the physical environment and the food that is available), a conch’s shell might actually form differently in size and even in shape. After all, the better adapted they are, the more likely they are to survive!

An adult "samba" conch shell (on the left) and an adult "broad-lipped" conch shell (on the right).

We have also been finding a lot of a small variety of conch we call “sambas”. They are like miniature versions of the big broad-lipped queen conch that usually represents the species. The samba adults are still recognized by the flared lip, but it is not as big and beautiful. We do not know what exactly causes these conchs to grow smaller (type of food, availability of food, water quality, genetics?), but scientific investigations have indicated they may be genetically different than the normal sized queen conch.

In the end, we don’t mind what they look like; they all get counted as queen conch. However, from what we have heard, fishermen do care what a conch looks like. The small samba conchs are harder to get out of the shell and the meat is tougher, so they are often skipped over. The really old conchs may be passed up too for the same reason. The large conchs with the broad shell lips are tastier and you get more return ($) for your effort. Is this preference by fishermen (what scientists call selective fishing pressure) having an affect on the overall fishery? If only the sambas are left to reproduce, is that what we can expect to see more of in the future? From what we saw in the Berry Islands and Andros, this could be happening already.

Thanks for checking in…

Catherine

 

Breaking news from the dive crew!

By Catherine | 11 July 2011 | No Comments
Published in Exuma Cays Expedition 2011, Uncategorized

Well everyone, at this early stage no real conclusions can be drawn about what we’re going to find in the deeper depths here in the Exuma Cays Land and Sea Park, but so far, we have found more queen conch on one transect than we did on all the transects we did (40) at Lee Stocking Island! We’ve also observed more mating and egg masses as well, which means more reproduction too. More conchs! More reproduction! Could the Park be living up to its reputation?

Ted carefully lifts a mating pair of queen conch off the bottom. If you look closely you can see the male's verge stretching into the female's shell. photo by C. Booker

Our new volunteers are a great bunch of people. Andy and Ted were with us in the Berry Islands in 2009, and Peyton and Jasmine have joined us for the first time. And of course, we still have Adric with us. So, we’re getting everyone trained in the field, and just starting to get into our daily work rhythm. Stayed tuned for posts from the volunteers’ perspectives on the project and the Exuma Cays Land and Sea Park!

The dive crew takes a lunch break in a protected cove. photo by C. Booker

Thanks for checking in…

Catherine

Welcome to the Exuma Cays Land and Sea Park

By Catherine | 6 July 2011 | No Comments
Published in Exuma Cays Expedition 2011, Uncategorized

After sailing steadily up the Exuma Cays chain, we have made it to the Exuma Cays Land and Sea Park! This no take marine reserve has been protected since 1986 years and is known as the oldest Park of its kind in the world. Diving and snorkeling here is like going back in time. The marine life is truly amazing and unlike anything you might see throughout the rest of the Caribbean. A few of us took a quick snorkel yesterday and immediately noticed the difference. Quite simply, there are a lot more fish. There are a lot more different species of fish. The fish are bigger and they seem uninterested in your presence. They continue with their daily fish lives, displaying typical fish behaviors as you watch (as opposed to diving for cover as soon as you get too close). On our snorkel we saw a large coral head with 10 lobsters hiding beneath it. We saw juvenile and roller conchs. We saw large predatory fish and lots of big parrotfish grazing away. It really is a special place.

The Park rules.

 

A large Black grouper in the Exuma Cays Land and Sea Park.

Scientists have been documenting the uniqueness of such a well-preserved ecosystem and the benefits it can have for fisheries conservation for many years. Scientific studies have shown that Nassau grouper biomass (a measure that captures both the number and size of a particular organism) inside the Park is much greater than outside of the Park, and that rates of parrotfish grazing (an important ecological process that keeps reefs healthy) are much higher in the Park (Mumby et al. 2006). Recently, scientists have found that in the Park there are fewer lionfish (an invasive species) on reefs where there is high grouper biomass. In places outside of the Park where grouper populations have been depleted, there are more lionfish, so it seems having more large grouper may help control this invasive species (Mumby et al. 2011). About 20 years ago, Dr. Allan Stoner and colleagues found that the density of conch (the number of individuals per area) in the Park is 31 times greater than densities on the fishing grounds around Lee Stocking Island (Stoner and Ray 1996). And that is, of course, why we are here today; to determine if those conch densities are still really high here in the Exuma Cays Land and Sea Park.

Adric Olson and with Brenda from Breda's Kitchen take-away on Little Farmer's Cay.

 

Aiden Burrows of Little Farmers Cay prepares freshly caught conch for the fryer.

On our way here, we stopped by the settlements of Little Farmers Cay and Black Point to talk to fishermen about their experiences in our study areas. We had a good conversation with fishermen on Little Farmers Cay about the conching grounds around Lee Stocking, and enjoyed a delicious conch dinner from one of the local take-away restaurants. At Black Point I was able to make some good contacts for a future meeting with the fishermen there. People found it very amusing that we were headed to the Exuma Cays Land and Sea Park to count conch. They told me we were going to get tired of counting conch because there are SO MANY in the Park! They also warned us that we might see sharks…I told them I hoped so!

Until next time…

Catherine

Wrapping up at Lee Stocking Island

By Catherine | 1 July 2011 | No Comments
Published in Exuma Cays Expedition 2011

Well, we have said goodbye to 3 of our volunteers for the Lee Stocking Island leg of the trip and are heading north today. We really, really appreciate the time and dedication Jamie, Karl, and Alannah gave us while here. They did a great job! We got our work done and managed to have some fun doing it. Here are a few pictures of the crew…thanks guys!

Jamie, Karl, and Adric head to the next dive site.

Alannah records data while Martha drives the boat.

Jamie checks out the other marine life (besides conch) after swimming a transect.

Next we are going to Little Farmers Cay, which is about 15 miles north of Lee Stocking. No surveying there, but we will meet with some fishermen to talk conch. After that we will keep traveling up the Exuma Cays to Black Point, and then Staniel Cay. We hope to meet with some folks there too.

More posts are on the way, so be sure to check back again soon!

-Catherine

DID YOU KNOW?

Bahamas coast

Conchs are native to the coasts of the Caribbean, the Florida Keys, The Bahamas, and Bermuda.

MORE FACTS >>