The Chesapeake Ray

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I heard a piece this morning on NPR on a recent IUCN – the International Union for Conservation of Nature- report on sharks and rays. (NPR). According to the piece, 25% of the world’s sharks and rays are threatened by extinction. This got me thinking about the Chesapeake Bay. I know we have had sharks and rays in the Bay, but I wasn’t sure about their status. What I found was pretty interesting, and fitting, given my piece yesterday on oyster farming:

In the Bay we have the the cownose ray (species name Rhinoptera bonasus). The ray lives in Chesapeake waters from May to October, feeding on molluscs, like oysters and clams.

A 2011 report in the Chesapeake Bay Foundation’s Save the Bay magazine comments on the negative impact rays have on the oyster and seagrass populations in the Bay, (p. 15). Seagrasses and the oyster industry have seen a bit of a comeback after decades of trouble. To protect this growing industry, many in aquaculture called for the ray to be fished or killed off in large numbers.

The 2011 report, “Misunderstood: The Cownose Ray” hazards against overfishing the ray. The species is native to the Chesapeake, and plays an important role in the natural ecosystem. Sometimes the role of a species is not completely understood until it is no longer there to perform it. The article mentions an approach on the West Coast where the aquaculture industry targeted rays to protect their farms. The rays were in fact eating other oyster predators, and when the ray numbers went down, so too did the oyster population.

Scientists argued for more natural solutions to the problem in the Chesapeake region. They called for better management of ray predators (native sharks), the use of oyster cages and other forms of repellent to prevent ray feeding. By touring my neighbors oyster farm, I’ve seen that oysters are grown in cages, perhaps in part because of the ray issue. But I’m curious to find out more- on the ray population today and the species current interaction with aquaculture and underwater grasses. Has anything changed, improved? I’ll be looking for more information in the next few days and sharing what I find.

Sources: Chesapeake Bay Program, Chesapeake Bay Foundation

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