FOR IMMEDIATE RELEASE
March 4, 2002
Two Gulf sturgeons from the U.S. Fish and Wildlife Service’s Warm Springs Regional Fisheries Center in Georgia are seeing more clearly this week, thanks to successful cataract surgeries performed at North Carolina State University’s College of Veterinary Medicine in Raleigh. The surgeries were done February 19 and 20.
“Although North Carolina State has been doing animal cataract surgeries for several years, we believe this is the first time nationwide anyone has ever conducted cataract surgeries on fish,” said Robert Bakal, Veterinary Medical Officer of the Warm Springs Regional Fish Health Center.
“When you have cataracts, it is like trying to see through frosted glass. Shadows are visible, but it is hard to see images or details,” said Sam D. Hamilton, the Service’s Southeast Regional Director. “These fish may some day be released into the wild, and removing their cataracts could greatly improve their chances for survival.”
Brian Gilger, DVM, Associate Professor of Ophthalmology at North Carolina State’s College of Veterinary Medicine, and his staff performed the surgeries. First, a healthy Gulf sturgeon, without cataracts, was examined to determine how a normal sturgeon’s eyes appear. Then, an electroretinogram (ERG) was conducted, both on the healthy sturgeon and the other two sturgeons, to measure their retinas’ ability to respond to light. Never before had ERGs been performed on sturgeons, although in 1988 North Carolina State used an ERG on the fish, menhaden. The results indicated that the retinas were healthy in all three fish, which meant that removing cataracts for the impaired fish would improve their vision. The ERG also showed that Gulf sturgeons potentially might have the ability to see color and that they see better in light conditions.
Both fish were anesthetized for the surgical procedures which each lasted about an hour. The fish were kept alive, anesthetized, and out of the water using a special fish anesthesia machine. The cataracts were removed by making a small incision in the cornea and then using phacoemulsification to remove the lens. Using ultrasonic energy, phacoemulsification breaks the eye lens into small pieces that are sucked out of the eye. The procedure takes place under a surgical microscope. The cataract surgeries on both fish appear to be successful. However, when mammals’ eye lens are removed, the procedure leaves them slightly far-sighted. This is often correctable with prosthetic lenses, but these are not currently available for fish.
“The sturgeon cataract removal went very well,” said surgeon Dr. Brian Gilger. “We had to modify the standard surgical procedure slightly to accommodate the fish’s hard lens and small eye. "As with any surgical procedure, as we got more experience the procedures went smoother. The fourth eye went much quicker and easier than the first eye. All eyes looked fine after surgery, and I think they will do quite well.”
The surgeries were filmed for the Discovery Channel’s Animal Planet and will be aired on April 16.
“I’m very grateful for the tremendous partnerships that the U.S. Fish and Wildlife Service has throughout the country with people at universities and with state resource agencies," said Bakal. “We do not have, nor can we afford, the expertise or equipment that a case like this requires. We have gained some great information about these animals and have helped them to see, which gives them an even higher quality of life.”
Bakal and Brian Hickson, Fisheries Biologist at the Fisheries Center, transported these fish to and from the Warm Springs Regional Fisheries Center to North Carolina State. The trips took about 10 hours each way. Bakal and Hickson also diagnosed these fish with cataracts, anesthetized them before their surgeries, and assisted in their recovery process.
Beginning in May, both fish, along with several others, will be implanted with radio and sonic transmitters and released into the Apalachicola River system of Florida and Georgia. Service and Georgia Department of Natural Resources biologists will track the fish for about a year to determine if they behave like wild fish. If they do, this technique of releasing sentinel fish will be used to evaluate potential habitats and locate remnant wild populations in this and other river systems.
A subspecies of the Atlantic sturgeon, the Gulf sturgeon is federally listed as threatened. Their snout is bladelike, and their body color is light brown to dark brown and pale underneath. The sturgeon reaches a maximum length of about eight feet and weighs as much as 500 pounds. The fish is anadromous, participating in fresh water migrations. Sturgeon apparently only eat during their stay in marine waters; food items are rarely found in the stomachs of the fish sampled in rivers. A long-lived fish, most individuals live at least 28 years. The Gulf sturgeon is only found in the Gulf of Mexico and its drainages, primarily from the Mississippi River to the Suwannee River, in Louisiana, Mississippi, Alabama, and Florida.
The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System that encompasses more than 540 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 70 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores national significant fisheries, conserves and restores wildlife habitat such as wetlands and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state and fish wildlife agencies.
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