Lifting a lobster casita
is easier than it looks. The device is little more than an underwater cement table on stumpy legs that most people in the Caribbean use in place of lobster traps. To collect the spiny lobsters native to the area, you simply plant your feet in the sand, take a breath, duck into the four-foot-deep water, and flip up the trap. “You have to keep it from falling backwards!” says Mexican fisheries expert Kim Ley Cooper in exasperation. “Ah, there’s too much sand to see anything.”
A small ripple
had grabbed the platform like a sail, pushed it vertical and lifted my furiously kicking feet out of the sand like I was a rag doll. In the moment before my feet lifted, I saw the casita’s
inhabitant scuttle past to freedom. Casitas
(or “little houses”) are found in lobster fisheries throughout Latin America and parts of Australia. The idea is simple: because spiny lobsters crave shelter, covered structures attract them just as well as baited traps. They require little maintenance, are easy to monitor and yield as many if not more lobsters as conventional traps.
Their effectiveness, however, has led them to become a flash point among Florida fishing communities. Illegal versions—historically made simply of metallic or appliance garbage dumped in the shallows—have given the device a bad reputation in the U.S. A dedicated cadre of dive fishermen, however, are calling for cleaner versions (like those typically used in Mexico) to be legalized, arguing they are friendlier to the environment than conventional traps. But fishers are not convinced and worry that the devices are so effective (pdf
) that they may forever change a marine way of life. All this leaves scientists to wrestle with the question: What’s the best way to catch a lobster?
Spiny lobsters, which live in the Caribbean and along the Pacific coast, are very different from iconic Maine lobsters. The latter American species—with massive claws that diners struggle to crack in restaurants—live in cold, dark water and are aggressive toward one another. Spiny lobsters have no claws, forage at night and happily congregate during the day under whatever they can find—be it rocks, coral or debris. In fact, spiny lobsters are so friendly that any piece of cover quickly becomes a magnet for them; they will pack themselves carapace-to-carapace into a crawl space in a matter of weeks, even though they could come and go as they please. Fishermen then simply dive to the shelter and reach in with a sort of metal lasso to snatch them out.
Lobsters today are unquestionably the biggest fishery in the Caribbean. Thanks to a hungry Chinese market, the crustacean fetched as much as $18.50 per pound at one point last year for live spiny lobsters. (The U.S. only eats spiny lobsters that have been frozen.) Florida fishermen alone catch more than five million pounds per year, mostly around the Keys.
In U.S. waters lobsters are caught in conventional traps, cages with one-way entrances and a long rope for hauling up the catch. With so many traps in the sea, some get loose from their buoys and become tangled in coral or bump around aimlessly. As much as 1,600 kilometers of rope is thought to be lost from traps every year. “Lobsters are the highest value species in the entire Caribbean,” says Tom Matthews of the Florida Fish and Wildlife Conservation Commission. But “there are far too many traps used in Florida than what would be needed to harvest all the lobster.”
Matthews has been looking at casitas
as a potential companion to traps in the U.S. In a recent (unpublished) study he showed that in one lobster-rich area in the Florida Keys, casitas
enabled fishermen to collect the same volume in one month that trappers could catch in three.
But trap fishermen say that many of these casitas
are little more than junk piles. “Car hoods, PVC pipe, corrugated metal sheets, appliances, bathtubs. God, I’ve even seen boat trailers out there,” says Bill Kelly, executive director of the Florida Keys Commercial Fishermen’s Association. “On the Gulf side, roughly five to six miles off in some areas, we have continuous walls of casitas
that extend for miles.” Casita
fishing has been illegal in the U.S. since the 1980s when illegal fishermen made junk-pile casitas,
which during storms can cut coral reefs to ribbons. That’s the image that most people have of casitas
but in the past decade improved designs have emerged, and with them a devout group of U.S.
fans of the little houses. “It’s the 21st century, why are we still using an archaic 1940s box?” says Jim Sharpe, director of pro-casita
Environmentally Concerned Commercial Divers, based in Big Pine Key, Fla. “We’ve got a better mousetrap.”
Sharpe says the days of junked refrigerator casitas
are long gone and that modern versions are attached to the ocean floor and thus can’t be blown onto the reef during a storm. Many even have a place to clip a boat line so that fishermen do not need an anchor, which also could otherwise damage reefs. Traps require bait (often other lobster), but casitas
do not, which means smaller lobsters that might have been bait can go on to breed or be harvested later. And lastly, lobsters left in a trap that has separated from its mooring will eventually die, doing no good for either fisherman or the environment.
For retrieval, however, free divers must swim to depths as far as nine meters to retrieve lobsters by hand. That free-diving component, irrelevant with trap lobstering, is key to why conventional lobstermen see casitas
as a threat to their livelihoods. “We have no interest in a casita
fishery,” Kelly says. “We have a traditional trap fishery that serves the industry well.”
The conflict has become remarkably heated. The legal standing of casitas
in the U.S. may depend on whether they cause less environmental harm than traps do. Both do some damage: Scientists have known for awhile that casitas
form a halo of unvegetated sand around them. But careful examination reveals that traps do as well
, and might even be worse because they can swing 15 meters in a circle, damaging ocean life.
In addition to operational traps, Matthews (who doesn’t promote one fishing method over another) says that based on surveys of professional lobstermen as many as 100,000 traps are lost every year—a fifth of all traps, posing a threat to reefs and wasting any lobsters caught in them. Kelley says that number is about five times too high but was not able to provide data. If Matthews is right (he plans to publish two papers on the matter soon), it could mean that traps are causing far more damage to the corals than previously thought.
Ley Cooper, with NGO Razonatura, which works to empower coastal communities throughout the Yucatan Peninsula, sees casitas
as an easy solution to the problem. As long as fishing grounds are divvied up fairly and fishermen are forbidden from using scuba, casitas
are the most sustainable way (pdf
), he says, to catch lobster. (Mexican divers must free dive and thus do not harvest breeding lobsters from deeper water, unlike other countries such as Honduras, where the lobster population has plummeted because scuba divers take everything.)
Either way, we in the U.S. won’t see a casita
-based fishery soon. Last summer the National Oceanic and Atmospheric Administration ended an investigation into their potential, effectively shutting the door on legal casitas
“Managing lobsters is easy,” Matthews says. “It’s managing people that’s difficult. Culturally, I would say that casitas
are not compatible with south Florida. However, culture can change.” Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
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