A billionaire East Coast investor and six-figure donations from corporate giants are helping fuel assertions from both sides in the Stand for Salmon debate that out-of-state money and motivations are driving opponents' campaigns.

The industry-led opposition to the ballot measure says large corporate contributors, such as ConocoPhillips, are rooted in Alaska and have the state's best interest at heart. They charge that Outside nonprofits with questionable intentions have played a key role in the measure, which seeks to strengthen fish protections in Alaska.

"I think this is an anti-resource-development agenda" from Lower 48 groups with national ambitions, said Willis Lyford, a Stand for Alaska consultant.

The measure's supporters, meanwhile, say the multinational giants are more interested in global profits than protecting Alaska's environment.

The fight over Outside contributions is coming "from people who want to drill for oil, mine, do all these activities in Alaska that will irreparably harm our salmon," said Stephanie Quinn-Davidson, a measure sponsor and former state biologist.

One measure supporter is John Childs, a billionaire investor from Boston with a luxury fishing lodge in the Bristol Bay region, where the Pebble mine prospect would be developed.

Childs gave $100,000 to the salmon campaign in February — the largest cash contribution of the more than $1 million raised. Childs sits on the board of Wild Salmon Center in Portland, Oregon, one of the Lower 48 nonprofits contributing to the campaign alongside Alaska groups.

Childs said he's a fisherman and sees the measure as an effort to protect Bristol Bay fish from the "potentially catastrophic dangers of Pebble mine."

Meantime, Stand for Alaska has received more than $10 million from firms with Alaska operations and Outside headquarters, including a recent $600,000 injection from Texas-based ExxonMobil.

Alaska campaign regulators are currently weighing a Stand for Alaska complaint assertion that "dark money" from Outside nonprofits is powering the other side. Alaska voters can't track the "true source" of many contributions supporting the measure, the complaint says.

Groups involved with Stand for Salmon say they've worked hard to be transparent and follow the law. Ryan Schryver, ballot-measure campaign director, said industry is trying to distract attention from the measure.

"This is like comparing apples to hand grenades," Schryver said. "They have huge contributions from Outside corporations, and we have nearly 1,000 Alaska-based (small) donors. The last time I looked they had fewer than 50 Alaskans contributing. It's pretty clear who's representing the voices of everyday Alaskans."

Stand for Alaska officials say an opaque web of Outside nonprofits supports Stand for Salmon.

"This is trying to be painted as a David and Goliath story, but David still has to follow the law," said Kati Capozzi, Stand for Alaska campaign manager. "Alaskans still deserve to know the money is coming from, no matter which side you are on."

Stand for Alaska asserts one "dark money" source is New Venture Fund of Washington, D.C., giving more than $200,000 in pro-measure contributions.

New Venture supports budding progressive causes nationwide, providing financial and administrative support, officials said. It employs some Alaskans who have worked on the campaign, including Schryver.

Tim Bristol, head of SalmonState, an Alaska group supported by New Venture, said both sides receive Outside support.

"Does all of Kinross' money come from Alaska?" he said, referring to the Canadian-based owner of Fort Knox Gold Mine near Fairbanks. "Does ExxonMobil's?"

Stand for Alaska contributions include:

• $1.1 million from ConocoPhillips in Alaska, the state's leading oil producer, its parent company in Houston, Texas.

• $1 million from BP Exploration Alaska, operator of Prudhoe Bay oil field, parent company in London.

• $1 million from Kinross Fort Knox, parent company in Toronto.

Those and other companies supporting Stand for Alaska provide thousands of in-state jobs and inject billions of dollars into the state, while taking extra measures to protect the environment, Lyford said. They'd naturally want to stop a measure that would hurt development plans and the economy.

"The $1 million contribution comes directly from BP Exploration Alaska," said Megan Baldino, BP spokeswoman. "We've been here 40 years, and we hope to be here another 40 years."

"We're about as Alaskan a company as there is," said Natalie Lowman, ConocoPhillips Alaska spokeswoman.

Stand for Salmon supporters say their measure will not hurt business in Alaska. But it will protect commercial fishing, sport fishing and tourism, while also adding thousands of jobs and billions of dollars to the economy.

Alaskans are driving the salmon side, said Emily Anderson, an Alaskan who helped write the initiative.

The initiative sponsors are Alaskans, including Gayla Hoseth, an Alaska Native from the Bristol Bay region. More than 40,000 Alaskans signed it.

"This was spurred on by a lot of people in Alaska," she said.

Anderson is Wild Salmon Center's Alaska program director. The Portland nonprofit has contributed more than $100,000 to the campaign, about half in cash. The rest came in nonmonetary contributions, including travel and wages for Anderson's help, such as legal advice.

Wild Salmon Center's board includes Childs, owner of Crystal Creek Lodge more than 50 miles south of Pebble.

Childs founded J.W. Childs Associates, a private equity firm in Massachusetts that buys and sells companies. He's worth $1.2 billion, says research firm AffluenceIQ.

Childs said his lodge is not far from the Nushagak and Kvichak rivers, headwaters straddled by the Pebble copper and gold deposit. The rivers are major contributors to the world-renowned Bristol Bay sockeye salmon fishery.

Childs, 77, said in an email Pebble poses "unacceptable risk" to salmon, echoing comments of some Alaskans who fear mining waste could destroy fish habitat. He says the world is already adequately supplied with copper and gold.

Pebble Partnership, a $1 million contributor to Stand for Alaska, and owned by Northern Dynasty Minerals of Canada, says it has taken numerous steps to address environmental criticisms, including reducing the project footprint and not using cyanide to extract gold.

Childs said Alaska lawmakers failed to approve legislation boosting fish protections, a step he preferred, leaving the "blunt" initiative as the only available tool.

He says Alaskans shouldn't doubt his motivations: "While not (an Alaska) citizen, I am a property owner and one who loves the Alaska fishing and wilderness experience."

"Let me point out I'm a businessman and have no interest in hurting Alaska business. On the contrary," he added. "But when faced with the choice of a lucrative business venture and the risk of potentially catastrophic and irreparable damage to a great natural resource like the Kvichak, I'll choose the river every time."