By Richard Leong

NEW YORK (Reuters) - If sushi lovers think the price of their favorite raw fish is too high already, then new documentary "The End of the Line" may shock them with its argument that the real cost may be some species' extinction.

The film from director Rupert Murray, which is playing in art houses in the United States and United Kingdom, makes the case that consumer ignorance, clout of the fishing industry, and rising sushi demand in the West are causing "crashes" of numerous fish populations, leading to their "collapse."

"Food is one of the ways we have a massive impact on the planet," Murray told Reuters about his movie, which is based on the book of the same name by U.K. journalist Charles Clover.

A dire prediction cited in the film is most seafood will disappear in 40 years if current fishing practices persist -- a forecast the fishing industry and officials dispute.

"All the federal (fish) stocks are trending in the right direction. Very few will be considered overfished," said Dan Furlong, executive director of the Mid-Atlantic Fishery Management Council.

Indeed, U.S. fish stocks are better managed, such as those in Alaska, whose fishery program is shown in Murray's film.

But others species like the bluefin tuna and the Chilean sea bass -- have not been so lucky. Huge demand, plus questionable hunting practices, for these fish are pushing them near extinction, according to Murray.

"An industrial fleet can wipe out a species in about 10 years," he said.

Ironically, fewer big fish like bluefin tuna have led to increased supply of lobsters and shrimps, which big fish feast on. Scientists in the Murray's films, however, cautioned this rise in shellfish is temporary because they will eventually be overfished too.

"The food chain is the eco-system. I don't think we understand the impact of it (all)," Murray said.

Murray said seafood restaurants and celebrity chefs can play vital roles to promote responsible fishing.

In the film, Clover pursues Nobu, a well-known high-end sushi chain, to stop serving bluefin.

"We are not advocating giving up eating fish," Murray said. "If we fish it properly, it will be there forever. It's really a no-brainer really."

Despite his concerns, Murray said the tide may be turning.

"I'm very hopeful actually," he said. "We are just at the beginning of the line."