Cownose rays

In this photo from the Chesapeake Bay Foundation, a member of the organization’s educational staff holds a cownose ray. The rays are seen by some as a pest in the Chesapeake Bay, though researchers disagree with that assessment.

CHESTERTOWN — With its flying saucer-shaped body, bizarre eye placement and eerie mouth, the cownose ray typically is viewed as a harmful alien invader in the Chesapeake Bay, and there seem to be more of them this year.

In an interview last month, Kent County Waterman’s Association President Chuckie White said the species is depleting the blue crab population and tearing up the Bay grasses other species use for habitats. Another concern stems from aquaculture and rays feeding on cultivated oyster beds.

“It’s incredible how much of an eating machine the skate is,” White said.

Across the state, others have taken action against the rays.

In the Patuxent River Battle of the Rays tournament, held June 13 in Mechanicsville, participants hunted down rays with weapons such as bows and arrows, to see how many they could collect. After determining the winner of the contest, the rays’ bodies were dumped into the river. It sparked outrage in animal rights groups and other organizations.

In a telephone interview Tuesday, June 30, Maryland Department of Natural Resources Public Information Officer Karis King said the cownose ray is a species that is “not managed on a state or federal level,” meaning the rays are not being harvested and sustained in a fishery.

The cownose ray, or Rhinoptera bonasus, has a wingspan that can be up to 3 feet and can weigh as much as 50 pounds. The female of the species grows larger than the male.

Virginia Institute of Marine Science Fishery Specialist Robert Fisher, who has studied rays since 1990, said the biggest cownose ray he ever found was a 21-year-old female that measured 42 inches from wingtip to wingtip.

According to Fisher and other experts, however, the cownose ray is not as devastating as most believe.

Peyton Robertson, director of national marine fisheries services for the National Oceanic and Atmospheric Administration’s Chesapeake Bay office, said while cownose rays have been referred to as an “invasive species” to the Bay, that is not the case.

“Invasive means ‘non-native’ in fishery speak, but the ray is migratory, moving in and out of the Bay,” he said. “They’re not some new alien species. They’ve been here longer than we have.”

Fisher, speaking Wednesday, July 1, said cownose rays migrate up and down the coastline for reproduction. He said the rays usually live in the Bay from September to the middle of October, then travel south for warmer waters.

Fisher said another misconception is the cownose ray and the skate are the same animal. He said rays give live birth, while skates lay eggs.

“It’s detrimental for the ray to be associated with the skate, because of the negative perception,” he said. “It goes against us trying to educate watermen about the difference.”

Robertson said NOAA conducted a study several years ago about the ray’s dietary habits, and oysters, clams and crabs were “not found to be a significant part” of the diet.

“Rays prey on those species, but we don’t think they’re wiping out whole regions,” he said.

Fisher said during his research, he’s found rays usually feed on “thin-shelled bivalves,” such as mussels, razor clams and soft-shell clams. He also said mud crabs were usually the only crustacean rays eat.

“In my work, blue crabs have hardly been part of their diets,” he said.

Fisher also said cownose rays do not purposely destroy Bay grass beds. He said though the grass is uprooted during a ray’s mining for food, it can be recolonized.

“Their whole existence is to crush their prey,” he said. “They don’t feed on submerged aquatic vegetation.”

Bill Goldsborough, the Chesapeake Bay Foundation’s fisheries program director, said rays have hunted in the area for eons. He said though grass beds are down 20 percent, it’s no major fault of the rays.

He also said oyster farmers in the lower Bay have reported a loss of seed oysters due to cownose rays. However, he said this is due to a shortage of soft-shell clams, a ray’s main food source.

“If a fish doesn’t have a preferred food, it’s going to find something else,” Goldsborough said.

Fisher said the cownose ray is “an apex predator that’s been here for millions of years,” and the shellfish industry began to “villianize” the cownose ray in the early 2000s. However, he said oyster planting is “like ringing the dinner bell” for rays.

“It’s like feeding them popcorn. ... You can’t expect them not to feed on prey that’s right in front of them,” he said.

Robertson said efforts to create a fishery or other management plans for the cownose ray have been unsuccessful so far because of the species’ large population.

Fisher said another issue is rays mature late and have long gestation periods. He said females typically give birth to one pup per year.

He said it’s hard to have fishing regulations or direct fisheries because of variables such as how many rays to remove, mortality rates and the population size.

“For NOAA, we would be concerned about decimating the species without any science or knowledge,” Robertson said. “Some people would prefer to move ahead anyway, but we need to look at it from an ecological standpoint.”

Fisher said his research has show the cownose ray can be marketed economically. He said like their cousins the sharks, a ray’s meat, hide and liver oil can be used.

“The activity itself is not a bother,” he said of the Battle of the Rays torunament. “It’s the timing, regulations and non-utilization that bothers me.”

Robertson said while different species of fish are harvested in different ways, “dumping them aside without a thought is inappropriate.”

Goldsborough said several factors could be attributed to the Bay’s “imbalanced food web.” He said though the cownose ray may have an effect, the species is not the main culprit.

“There are more rays now, and though their impacts may seem problematic, I think it’s a matter of perception,” he said. “We just have to be careful to trace the issues back to the actual causes.”

Tags

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
PLEASE TURN OFF YOUR CAPS LOCK.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.