2 rivers, 2 sturgeon types
Fish-sampling researchers detect unexpected divergence
Copyright © 2001 Blethen Maine Newspapers Inc.
FARMINGDALE — Researchers are discovering discernible differences — including variations in DNA — in the same species of a rare saltwater fish that spawn in the Kennebec and Androscoggin rivers.
"I was surprised. The DNA was a little bit different," said Tom Squires, a scientist with the state Department of Marine Resources. Physical characteristics on the endangered shortnose sturgeon, such as body length and distance between eyes, was more significant in the two-river comparison.
The DNA finding was unexpected because the department's fish-sampling study was designed primarily to determine the population of the grayish-brown saltwater fish that swims up the two rivers in late April and May to lay eggs. For about 11 months of the year, all of Maine's shortnose sturgeon live and mix together in Merrymeeting Bay, Squires said. 
Staff photo by ANDY MOLLOY Department of Marine Resources technicians Vaughan Crandall, left, and Colin Clark haul in a net containing a shortnose sturgeon Monday in the Kennebec River in Farmingdale. The fish measured about 3 feet long, Crandall said.
Researchers believe underwater temperatures and environmental differences in the Kennebec and Androscoggin influence physical and genetic traits in the fish. DNA, the acid found mainly in the nucleus of cells, transmits hereditary characteristics through the generations.
Shortnose sturgeon can live 40 to 50 years and can grow up to 3 feet long. They begin to spawn at 12 to 14 years old.
The department is finishing the third year of a $52,000 study on the fish. The National Marine Fisheries Services is the sponsor.
"They wanted to know if these populations (Kennebec and Androscoggin) are the same or are distinct," Squires said.
When shortnose sturgeon are caught this year in the two rivers, researchers will measure the fish in several ways and also cut a small triangular section of tissue from tail fins.
That material, which is kept in an alcohol preservative, is sent to the New York Medical Center for DNA analysis.
Squires said the Department of Marine Resources will catch 50 shortnose sturgeon from the Kennebec and 50 from the Androscoggin for the 2001 study.
The same species of endangered fish also is being trapped for study in the Hudson River in New York. DNA and outer physical traits in those fish are also different from shortnose sturgeon born in the Kennebec and Androscoggin.
To reach Dan McGillvray
Phone: 621-5642
dmcgillvray@centralmaine.com