Biologist Argues Fishery is Risky Business

| April 24, 2012

 

Soon, cownose rays will be arriving at their summer breeding ground in the Chesapeake Bay. They swarm into the Bay, by some estimates in the millions, setting up an inevitable clash between man and fish that seems to escalate with each migration.

The rays — big mollusk-eating predators — are blamed for harming commercial oyster and clam fisheries and destroying delicate habitats as they feed. The rays’ presumed dining habits have earned them the ire of nearly every Chesapeake Bay constituency, despite their undisputed place as a native species.

Indeed, the cownose is a historical figure. While exploring the Rappahannock River circa 1608, a ray reputedly stung Captain John Smith as he speared it with his sword. According to lore, he was in such pain his crew feared he was dying and dug his grave. Smith recovered, however, and ate the ray for supper.

That is exactly what many people want to do with the ray today — put it on the dinner menu. There are both grassroots and organized movements under way to control their numbers. One proposed solution, vigorously promoted by the Virginia Marine Products Boards, is to establish a food market for cownose ray meat.

But scientists such as marine biologist John Morrissey of Sweet Briar College say that would be a bad idea.

“Establishing a sustainable fishery would be difficult because of the reproductive strategy used by this species,” Morrissey says. “They produce only one pup each year, and thus they are very vulnerable to overfishing.”

Moreover, Morrissey argues, it’s far from clear what impact the rays’ eating habits actually have on commercial shellfish populations. Since 2010, Morrissey and his students, along with colleagues at Hood College in Maryland, have been investigating the rays’ diet.

“What we and others, such as Bob Fisher at [Virginia Institute of Marine Science], hope to accomplish is to replace assumptions about their diet and impact on the bay with facts. What if their impact is much less damaging than is assumed, or much worse? This should be quantified before we launch an eradication fishery.”

Morrissey’s not in it for the glamour. The work he and his colleagues have chosen is painstaking and odorous, involving analysis of stomach and fecal content. Why do it?

To make us think twice about tampering with Mother Nature, something at which we almost never succeed, he says.

“The truth is, nobody can predict how the bay will respond if these apex predators are removed. The cure could easily be much worse than the curse. For example, we’ve removed mountain lions and coyotes from this area in an effort to make ourselves safer. And what happened? The deer population exploded, and now they are killing us when they crash through our windshields.

“There are many, many such examples, so that’s most important, in my view. I think it trumps whatever we find out about their diets.”

Morrissey is an expert on sharks, having studied them extensively in the wild and in the laboratory. He serves on the board of directors of the American Elasmobranch Society, an organization of professional ichthyologists who specialize in the biology of sharks, skates and rays.

He maintains a reproducing colony of chain catsharks, a small deep-sea shark species, on Sweet Briar’s campus. The live sharks allow him and his students to study the species’ natural history and to cover a broad range of research questions.

 

Contact: Jennifer McManamay

 

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Category: Biology, Uncategorized