SALISBURY COVE – Though Maine’s lobster industry is thriving, populations south of the state are struggling to survive a decline that researchers suspect may be linked to climate change, water pollution and a mysterious disease that attacks the crustacean’s shell.

Perhaps someday, the lobster’s genetic code can tell biologists how to protect the fishery that’s worth $200 million a year in Maine.

Toward that end, and thousands of other possible applications, scientists working at the Mount Desert Island Biological Laboratory have spent the past five months identifying the genes that make up a lobster’s biological blueprint.

To date, 5,000 genes have been identified and listed in the research project’s online genetic library, said David Towle, lead researcher on the lobster project.

Towle explained his work to colleagues and students during the 31st Maine Biological and Medical Sciences Symposium at the MDI Bio Lab on Friday.

Beginning in December, Towle and his research partners sampled tissue from each of the lobster’s major systems – its heart, brain, glands, muscles and reproductive organs – then used the samples to map lobster DNA, the unique combinations of nucleotides, the building blocks of life, that tell an organism when and how to develop.

The researchers use a sequencing machine, purchased with funding from the Maine Science and Technology Foundation, to identify between 500 and 1,000 of the individual nucleotides that make up any given gene. While these “tags” – long strings of the frequency and pattern of nucleotides – are not the entire strand, it’s typically enough to identify a gene as unique, Towle said.

About half of the lobster genes identified thus far have comparable genes in species like mice and humans that have been mapped in full, so scientists know their purpose. Genes across species are surprisingly similar – 99 percent of human genes have a similar companion gene in a mouse, according to researchers at Bar Harbor’s Jackson Laboratory.

The other 2,500 genes identified for lobsters were previously unknown to biology, Towle said.

“About half of the sequences came up with new data for which future science will have to be done,” he said.

The full lobster genome has not been sequenced, so it’s impossible to say precisely how many genes will eventually be found. But the number will likely run into the tens of thousands. The human genome contains between 30,000 and 40,000 genes – as does the genetic blueprint for the mouse and for a corn plant. Even the fruit fly has about 17,000 genes, researchers have found.

“What we really need is 50,000, rather than 5,000 [tags],” Towle said.

Elsewhere, partner institutions like the Hollings Marine Library in Charleston, S.C., are sequencing the genes of other marine organisms, such the blue crab.

Nearly 40,000 genetic sequences for 11 different species are now available, free to researchers at marinegenomics.org.

In Salisbury Cove, the lab’s equipment is capable of sequencing just under 200 genes every day, and work on lobsters, dogfish sharks and skates will continue, so long as funding is available, Towle said.

“The goal is to identify as many new genes, as quickly as possible, with the minimum amount of funding,” he said.