The tribe is concerned because its members traditionally eat large amounts of fish from the Penobscot River. In recent years, that tradition has been threatened by pollution, especially from dioxin and mercury.

Mercury, a natural element also produced by making chemicals and burning coal and trash, can be toxic to fish, wildlife and humans at high doses. Dioxin is a toxic byproduct of papermaking, which can be discharged in mill wastewater.

About 500 Penobscots live on the reservation. Indian Island is connected by bridge to the west bank of the Penobscot River in Old Town. Many more tribal members live in the surrounding area, about 10 miles north of Bangor.

Dioxin contamination in the river has forced many Penobscots to abandon tradition and fish more frequently from the lakes on tribal lands. Dan Kusnierz, director of water resources for the Penobscot Nation, said tribal members thought they would be safe eating lake fish.

But now the lakes are contaminated, too. Mercury, falling from the sky, has led the state to post fish consumption advisories for every lake, pond, river and stream in Maine.

Penobscot tribal members know their health is at stake.

''Tribal members are worried about going from the frying pan into the fire,'' Kusnierz said.

He has tested fish for mercury contamination from four of the 10 lakes on tribal lands.

Kusnierz found mercury in all the fish he sampled. Levels varied among the lakes and depending on the age, size and species of fish tested. Older, warm-water fish like perch and bass had the most mercury. Younger, cold-water fish like trout and salmon had the least.

His findings mirrored those of state biologists, who have tested fish in other lakes across the state.

Using the data he collected, Kusnierz altered the blanket, statewide advisory issued by the Maine Bureau of Health and posted specific, detailed advisories for Penobscots to follow when fishing on tribal lakes.

The Penobscots also have written a plain-English pamphlet of their own describing freshwater fish advisories and the dangers posed by mercury and dioxin. Those pamphlets are passed out to Indians when they get fishing licenses, and have been published in the island's newsletter.

Kusnierz said the advisory was simplified and rewritten in the Penobscots' pamphlet. The reason: People couldn't understand the advisories written by the Maine Bureau of Health.

''It didn't look that complicated to me as a scientist,'' he said. ''But other people would look at it and their brains would shut down.''

The tribe's natural resources and health departments are studying fish consumption rates within the tribe and the health problems that face reservation residents.

Kusnierz said it has been difficult to develop an accurate estimate of fish consumption because so many Penobscots have already cut back the amount of freshwater fish they eat.

Studies have found that Indians in the Pacific Northwest, however, eat an average of 1 pound of freshwater fish a week. That compares with an average of 2 ounces a week for the general population, according to the Environmental Protection Agency.

The health of Indian Island residents has been studied by experts from the Centers for Disease Control and Harvard University's School of Public Health.

But those results have been inconclusive. It remains unclear whether eating fish has affected the health of tribal members.

The Penobscots are trying to obtain grants to pay for more health studies.

The tribe also is intervening when environmental permits that allow industries to discharge pollution into the river come up for public discussion. The tribe's goal: To cut down on contamination from mercury and other chemicals.

For example, the tribes are opposing a proposed EPA permit that would allow HoltraChem Manufacturing to continue discharging small amounts of mercury into the Penobscot River from its chemical plant in Orrington.

The plant is downstream from the reservation, so HoltraChem may not be affecting fish in the area of Indian Island. But studies have found that eagles in the Penobscot watershed also have high levels of mercury and other contaminants in their systems, reducing their reproductive rate to 15 percent to 40 percent of the national average for the species.

To the Penobscots, the eagle is a sacred creature with important spiritual and cultural values.

The tribe also has appealed an EPA permit that set dioxin limits for the Lincoln Pulp & Paper Co. mill.

The Penobscots say they will remain vigilant. It will be a long battle, Kusnierz said, but ultimately the tribe aims to make fish from the river and lakes safe to eat again.

If so, that would give the Penobscots at least the opportunity to salvage a cultural identity that mercury, dioxin and the other byproducts of industrial civilization threaten to destroy.

If not their children, then maybe the grandchildren or great-grandchildren of Banks and other tribal members could toddle into canoes and bring home fish without fear.

''This is a very important part of the tribe's culture and spirituality,'' Kusnierz said. ''Being able to catch fish on traditional lands is very different than going to the store and buying them over the counter.''