Amateur anglers have a significant and possibly damaging impact on certain sea-fish populations, scientists claim.
Angling interest groups reject the scientists' assessment
Research centred on the US shows the combined catch landed by hobbyists can rival commercial outfits - especially for depleted stocks such as red snapper.
The Science magazine study says the US's 10 million saltwater recreational anglers may need better regulation.
"A few fish per person times millions of fishermen can have an enormous impact," said Dr Will Figueira.
The scientist from Duke University in Beaufort, North Carolina, added: "Their aggregate impact is far from benign.
Figueira and colleagues used all available federal and state data to compare commercial and recreational landings over the past 22 years.
Their analysis showed that amateur fishermen accounted for nearly a quarter of total catches of over-fished populations.
For some under-pressure species - particularly the large charismatic fishes that people care about most - recreational fishing was actually found to outstrip commercial landings.
This is true for red snapper (59% recreational) and gag (56%) in the Gulf of Mexico, red drum in the South Atlantic (93%), and bocaccio on the Pacific coast (87%), among others.
"The conventional wisdom is that recreational fishing is a small proportion of the total take, so it is largely overlooked," says lead author Dr Felicia Coleman of Florida State University.
"But if you remove the fish caught and used for fish sticks and fishmeal (pollock and menhaden) - two strictly commercially caught species that account for over half of all US landings - the recreational take rises to 10% nationally.
"And if you focus in on the populations identified by the Federal government as species of concern, it rises to 23%."
Not all are ready to accept the researchers' data and methods, however.
Karl Wickstrom, editor of Florida Sportsman magazine, told Reuters the researchers had included data on species like red fish in which there is no commercial interest and failed to take into account limits already in place on catches of certain species.
"This study is designed to obfuscate the fact that industrial level over-fishing is the cause of the global fishing crisis we have," he said. "There is a mountain of information saying commercial fishing is the cause of fish depletion."
And Jim Donofrio, executive director of the Recreational Fishing Alliance, also questioned the reliability of the report's data. For example, he pointed to a reported 35% jump in summer flounder catches. In reality, he told the Associated Press, torrential rains had kept anglers onshore, and the catches had dropped by 35%.
The scientists say more regulation may be needed
"We'll accept regulations. That's not a problem. But we will fight restrictions based on arbitrary data and inaccurate data," Donofrio added.
The research was sponsored by the Pew Charitable Trusts, which has supported a number of widely reported recent studies on the deterioration of the marine environment.