Cownose Rays Cause Concern

April 20, 2008

Release from: Ben Raines
Press-Register (Alabama)

Chocolate-colored wings flapping in unison as they ghost through the surf, a dozen cownose rays slip along Sand Island as the sun comes up.

The rays are hunting, flying just over the seafloor and watching intently as the beating of their powerful wings stirs the sand and uncovers bottom dwelling creatures.

Any sign of a clam or oyster, even a crab scuttling for safety, and one of the rays will peel off from the group and pounce, a pair of giant "teeth" inside its big suction cup of a mouth crunching oysters and crabs as easily as a person crunches a cracker.

Scientists know little about the large rays, and that has them worried, especially as the population in Mobile Bay and the Mississippi Sound appears to be increasing.

Along the Eastern Seaboard, the rays are blamed for wiping out North Carolina's century old commercial scallop harvest, a feat that was accomplished in just a few short years. In Chesapeake Bay, some believe cownose are one of the primary culprits behind massive, decades-long declines in the harvest of blue crabs and oysters.

For the last several months, the Dauphin Island Sea Lab has been studying the rays, trying to gain basic data, including what they eat, whether they stay year-round and how many there are in local waters.

"Cownose are very big, they consume a lot of food, and they migrate," said Matt Ajemian, one of the Sea Lab scientists. "We're very interested in these animals right now because they can change the dynamics in an ecosystem."

Few enemies What is known about the rays is that they are voracious, weigh from 20 to 60 pounds and have few natural predators. In fact, the only things believed to kill the adults -- which can measure 7 feet from wingtip to wingtip -- regularly are sharks and shrimp boats.

The name comes from the rays' distinctively shaped snout. Under the snout are sensors capable of picking up tiny electrical charges emitted by prey animals, even from a crab buried in the sand.

The goal of the Dauphin Island group is to figure out if the cownose swimming in the northern Gulf might pose the kind of ecological threat seen on the Atlantic coast here in Mobile Bay.

Ajemian said little is known about the rays because they have never been commercially important. Surveys done in the late 1980s showed that Mobile Bay and the Mississippi Sound had the highest density of cownose rays seen anywhere in the Gulf of Mexico.

"We really don't know much about their population in the northern Gulf," Ajemian said. "That's what our research is looking at."

Several times a month, Ajemian and his crew capture rays around Dauphin Island, using seines, gillnets and sometimes spears. Some of the captured rays are released alive after being fitted with radio transmitters in an attempt to figure out if the local populations migrate the way those in the Atlantic do, journeying annually from the Chesapeake area to Brazil.

But Ajemian gets a pained look on his face when he talks about the rays that must be "sacrificed" in the pursuit of science.

The largest ray captured on an expedition Thursday, a female, weighed about 25 pounds, and had a wingspan just shy of 3 feet. A dissection at the Sea Lab revealed that she was pregnant.

Rays are live-bearers, birthing but a single pup per litter, unusual in the marine world, where many creatures lay eggs by the millions. Nestled inside the mother ray with its wings folded tightly around its body like a bat, the pup was a perfect, pearly gray miniature of its mother, about the size of a slice of bread. Ajemian said it would likely have been born in early summer, and not reached maturity for three to five years after that.

So far, Ajemian has only examined the stomach contents of rays caught off Sand Island, in the Gulf. One of the rays caught Thursday had sand dollars and a small stone crab in its gut.

The group has just started collecting rays inside Mobile Bay, around Little Dauphin Island, but has yet to examine their gut contents. He said it would cause some concern if the rays in the bay were found to be focusing on either oysters or juvenile blue crabs.

Two factors are believed to have led to the apparent swell in the ray population in recent years.

First, many of the big coastal shark species native to American shores have suffered population declines of up to 90 percent since the 1970s. Second, the turtle excluder devices required on all shrimp boats since 1987 may be allowing the big, heavy rays to escape from the hundreds of trawl nets dragging the Gulf any given day.

But, so little is known about the Gulf's ray population, scientists can't be sure if their numbers have actually increased, at least not by looking at scientific data. Instead, what researchers are forced to rely on, for now, is anecdotal information from shrimpers, fishermen and others who spend a lot of time on the water.

For instance, Mobile Bay fishing guide Bobby Abruscato said he has seen a lot more of the rays in the last several years. Abruscato was raised on Dauphin Island and has been fishing in the bay for more than 40 years.

Beautiful swimmers The rays are beautiful swimmers, sometimes turning sharply, other times carving long graceful arcs. They move together as they swim, more like a squadron of small, aquatic fighter jets than a school of fish.

Swimmers and waders are seldom stung by the cownose, largely because it is a "flying ray." It swims or "flies" most of the time, seldom resting on the bottom like the two species of stingray common in Mobile Bay. Both the Southern and Atlantic stingrays hide in the sand and sting people who step on them.

The cownose is unable to whip its sting into people like those true stingrays because the serrated weapon is located at the base of their tail rather than halfway down it. But that is not to say cownose can't sting. They do, and given their large size, the pain is said to be excruciating.

In fact, John Smith, founder of Jamestown, was famously stung by a cownose ray in the Chesapeake back in 1608. Smith had speared a ray with his sword and was stung in the wrist, causing his arm and shoulder to swell, according to historical accounts. With their captain delirious from the pain and fearing the worst, Smith's men dug a grave near the water's edge. But Smith recovered enough by nightfall to eat the ray that stung him, and the spot is still known as Stingray Point.

While there is no record of how Smith's ray was cooked, there are various recipes on the Internet for fried ray, cownose kabobs and even curried cownose.

The state of Virginia has been trying unsuccessfully to create a commercial market for cownose since the mid- 1980s, largely in an effort to control the population, something that gives scientists heartburn. "These are slow growing animals. They have one pup per litter," said Ajemian. " I feel like you really have to do your homework to know if this a species that can be harvested commercially."

The scientist said a lot more would be known about the local population within a few years, including whether the rays pose any threat to local crab or oyster fisheries.