For The First Time, Biologists Track Cownose Rays To Florida And Back

[Judi Lynn]

Last edited Sat Sep 1, 2018, 01:18 AM - Edit history (1)

For The First Time, Biologists Track Cownose Rays To Florida And Back
August 24th, 2018, 11:07AM / BY Kristen Minogue



Cownose rays are migratory animals that come into the Chesapeake in summer and swim to Florida for the winter. (Credit: Jay Fleming/SERC)


Every summer, cownose rays stream into Chesapeake Bay to mate and give birth to their pups. When autumn comes, they disappear—presumably to migrate south, but no one knew for certain where they spent the winter. Now, after a three-year tagging study published Aug. 23 and led by the Smithsonian Environmental Research Center (SERC), scientists have solved the mystery. Cownose rays all along the Atlantic winter near Cape Canaveral, Florida, and it’s likely they return to the same spots each summer.

Cownose rays are large stingrays native to the Chesapeake, with dark brown or olive-gray backs and white bellies. They reproduce slowly. Most mothers give birth to only one pup a year, and don’t mature until age 7 or 8, making them vulnerable to intense fishing or sudden population declines. And yet cownose rays have been dogged by controversy. In the early 2000s they were saddled with partial blame for oyster declines because their diet includes shellfish. (Later studies cleared their names. Oysters had been declining years before cownose rays became more abundant, and oysters make up only a small percent of their diets. Though rays sometimes have taken advantage of unprotected juvenile oysters planted to restore reefs, in general they prefer weaker bivalves like soft-shell clams.) Later, in 2015, bowfishing tournaments for cownose rays began raising alarm among some Marylanders. In response, the Maryland government voted to become the first state to create a fishery management plan to conserve the cownose ray.

“Because of the slow birth rate, we know that if we don’t manage them, and instead harvest them in a way that heavily impacts the population and causes a population decline, it’ll take a long time for them to recover,” said Matt Ogburn, SERC marine biologist and lead author of the study. “If we lose something important, we could lose it for decades.”

The new study, published in Marine Ecology Progress Series, marks the first time scientists have tracked cownose ray migrations along the Atlantic coast for a full year or more. Knowing where they go every year will help fill in some longstanding knowledge gaps about the rays, as Maryland officials decide how to manage them. It’s part of the Smithsonian Institution’s new Movement of Life Initiative. Scientists from the Virginia Institute of Marine Science (VIMS) and Savannah State University also joined the effort.

Read more: http://www.smithsonianmag.com/blogs/smithsonian-environmental-research-center/2018/08/24/first-time-biologists-track-cownose-rays-florida-and-back/#V561q4qAluamWamL.99