New details of the Biden administration’s signature conservation effort, made public this month amid a burst of other environmental announcements, have alarmed some scientists who study marine protected areas because the plan would count certain commercial fishing zones as conserved.

The decision could have ripple effects around the world as nations work toward fulfilling a broader global commitment to safeguard 30 percent of the entire planet’s land, inland waters and seas. That effort has been hailed as historic, but the critical question of what, exactly, counts as conserved is still being decided.

This early answer from the Biden administration is worrying, researchers say, because high-impact commercial fishing is incompatible with the goals of the efforts.

“Saying that these areas that are touted to be for biodiversity conservation should also do double duty for fishing as well, especially highly impactful gears that are for large-scale commercial take, there’s just a cognitive dissonance there,” said Kirsten Grorud-Colvert, a marine biologist at Oregon State University who led a group of scientists that in 2021 published a guide for evaluating marine protected areas.

The debate is unfolding amid a global biodiversity crisis that is speeding extinctions and eroding ecosystems, according to a landmark intergovernmental assessment. As the natural world degrades, its ability to give humans essentials like food and clean water also diminishes. The primary driver of biodiversity declines in the ocean, the assessment found, is overfishing. Climate change is an additional and ever-worsening threat.

Fish are an important source of nutrition for billions of people around the world. Research shows that effectively conserving key areas is an key tool to keep stocks healthy while also protecting other ocean life.

Nations are watching to see how the United States enacts its protections.

The American approach is specific because the broader plan falls under the United Nations biodiversity treaty, which the United States has never ratified. The effort in the United States is happening under a 2021 executive order by President Biden.

Still, the United States, a powerful donor country, exerts considerable influence on the sidelines of the U.N. talks. Both the American and international efforts are known as 30×30.

On April 19, federal officials launched a new website updating the public on their 30×30 efforts. They did not indicate how much land was currently conserved (beyond approximately 13 percent of permanently protected federal lands), stating that they needed to better understand what was happening at the state, tribal and private levels. But they announced a number for the ocean: about a third of U.S. marine areas are currently conserved, the website said.

The problem, according to scientists, is how the Biden administration arrived at that figure.

Everyone seems to agree that the highly protected areas classified as marine national monuments should count as conserved, and they did: four in the Pacific around Hawaii, Guam and American Samoa that were set up and expanded between 2006 and 2016; and one in the Atlantic southeast of Cape Cod, designated in 2016. A vast area of the Arctic where commercial fishing is banned was also included, with wide agreement.

But other places on the list should not be counted unless protections there are tightened, said Lance Morgan, a marine biologist and president of the Marine Conservation Institute, a nonprofit group that maintains a global map of the ocean’s protected areas.

For example, 15 National Marine Sanctuaries are included. While these areas typically restrict activities like oil and gas drilling, they do not require reduced quotas of commercial fishing. High-impact fishing techniques like bottom trawling, which damages seafloor habitat and captures vast amounts of fish, are prohibited in certain sanctuaries but permitted in others.

Also included on the list are “deep sea coral protection areas” that ban seafloor fishing like bottom trawling, but not some other commercial fishing methods.

“Much more effort should be focused on improving the National Marine Sanctuary program and ensuring that new areas being created provide conservation benefits and ban commercial fishing methods like bottom trawling and long-lining,” Dr. Morgan said.

Senior officials with the Biden administration emphasized that ocean work under 30×30 was far from over. Very little of the conserved marine area is near the continental United States, for example, and one of the administration’s priorities is adding places there to make the effort more geographically representative.

But they defended the decision to include areas that allow commercial fishing. Despite the high-impact gear, national marine sanctuaries have long been considered protected areas by the United Nations, they pointed out. More generally, they said, the administration weighed various approaches to defining what it would count.

For example, while an atlas of marine protected areas maintained by Dr. Morgan’s group considers 25 percent of American waters to be conserved, the U.S. Fishery Management Councils puts that number at more than 72 percent. Administration officials said their number reflected important conservation work by a variety of agencies and stakeholders.

“We do have very highly regulated fisheries in the U.S.,” said Matt Lee-Ashley, the chief of staff at the White House Council on Environmental Quality, which is helping to coordinate the 30×30 effort. “And so, our domestic definition of conservation may be a little bit different, and other countries’ definitions may be a little bit different.”

Even though the United States has not ratified the biodiversity treaty, it will still submit a conservation total to be counted toward the global 30×30 commitment. Officials said they were still weighing which areas to submit.

In a statement, representatives of the Fishery Management Councils praised the inclusion of commercial fishing areas, noting that they are managed under “very stringent sustainability and conservation standards.”

But sustainably managed commercial fishing is what should be happening in the rest of the ocean, said Enric Sala, a marine biologist who studies and advocates for marine protected areas. Allowing commercial fishing in places conserved under 30×30, he said, is “padding the numbers.”

“People are looking up to the U.S.,” Dr. Sala, who is originally from Spain, said. “That sends a really bad signal.”